Nouns denoting animals
- abalone
- any of various large edible marine gastropods of the genus Haliotis having an ear-shaped shell with pearly interior
- Aberdeen Angus
- black hornless breed from Scotland
- abomasum
- the fourth compartment of the stomach of a ruminant; the one where digestion takes place
- abortus
- a human fetus whose weight is less than 0.5 kilogram when removed or expelled from the mother's body
- abrocome
- ratlike rodent with soft fur and large ears of the Andes
- Abudefduf saxatilis
- large blue-grey black-striped damselfish; nearly worldwide
- Abyssinian cat
- a small slender short-haired breed of African origin having brownish fur with a reddish undercoat
- Acanthisitta chloris
- small green-and-bronze bird
- acanthocephalan
- any of various worms living parasitically in intestines of vertebrates having a retractile proboscis covered with many hooked spines
- Acanthocybium solandri
- large fast-moving predacious food and game fish; found worldwide
- Acanthophis antarcticus
- venomous Australian snake resembling an adder
- acanthopterygian
- a teleost fish with fins that are supported by sharp inflexible rays
- Acanthoscelides obtectus
- larvae live in and feed on growing or stored beans
- Acanthurus chirurgus
- surgeon fish of the West Indies
- acarid
- very small free-living arachnid that is parasitic on animals or plants; related to ticks
- acarine
- mite or tick
- accentor
- small sparrow-like songbird of mountainous regions of Eurasia
- Accipiter cooperii
- bluish-grey North American hawk having a darting flight
- Accipiter gentilis
- large hawk of Eurasia and North America used in falconry
- Accipiter nisus
- small hawk of Eurasia and northern Africa
- Acherontia atropos
- European hawkmoth with markings on the back resembling a human skull
- Acheta assimilis
- common American black cricket; attacks crops and also enters dwellings
- Achoerodus gouldii
- found around the Great Barrier Reef
- acidophil
- an organism that thrives in a relatively acid environment
- Acinonyx jubatus
- long-legged spotted cat of Africa and southwestern Asia having nonretractile claws; the swiftest mammal; can be trained to run down game
- Acipenser huso
- valuable source of caviar and isinglass; found in Black and Caspian seas
- Acipenser transmontanus
- food and game fish of marine and fresh waters of northwestern coast of North America
- acridid
- grasshopper with short antennae
- Acridotheres tristis
- dark brown crested bird of southeastern Asia
- Acris crepitans
- a cricket frog of eastern and central United States
- Acris gryllus
- a cricket frog of eastern United States
- Acrocephalus schoenobaenus
- small European warbler that breeds among reeds and wedges and winters in Africa
- acrodont
- an animal having teeth consolidated with the summit of the alveolar ridge without sockets
- Actias luna
- large pale-green American moth with long-tailed hind wings and a yellow crescent-shaped mark on each forewing
- actinia
- any sea anemone or related animal
- actinomyces
- soil-inhabiting saprophytes and disease-producing plant and animal parasites
- actinomycete
- any bacteria (some of which are pathogenic for humans and animals) belonging to the order Actinomycetales
- actinomyxidian
- parasites of worms
- actinopod
- protozoa having stiff rodlike radiating pseudopods
- actinozoan
- sessile marine coelenterates including solitary and colonial polyps; the medusoid phase is entirely suppressed
- Actitis macularia
- common North American sandpiper
- aculea
- small spiny outgrowth on the wings of certain insects
- aculeus
- a sharp-pointed process especially a sting of a hymenopterous insect
- Adalia bipunctata
- red ladybug with a black spot on each wing
- Adapid group
- extinct small mostly diurnal lower primates that fed on leaves and fruit; abundant in North America and Europe 30 to 50 million years ago; their descendents probably include the lemurs; some authorities consider them ancestral to anthropoids but others consider them only cousins
- Addax nasomaculatus
- large antelope with lightly spiraled horns of desert regions of northern Africa
- Adelges abietis
- a variety of adelgid
- Adelges piceae
- a variety of adelgid
- adelgid
- any of various insects that feed and form galls on conifers
- Adenota vardoni
- an African antelope closely related to the waterbuck
- adenovirus
- any of a group of viruses including those that in humans cause upper respiratory infections or infectious pinkeye
- admiral
- any of several brightly colored butterflies
- adult
- any mature animal
- Aedes aegypti
- mosquito that transmits yellow fever and dengue
- Aegina
- small medusa
- Aegypius monachus
- of southern Eurasia and northern Africa
- Aegyptopithecus
- extinct primate of about 38 million years ago; fossils found in Egypt
- Aepyceros melampus
- African antelope with ridged curved horns; moves with enormous leaps
- aepyornis
- huge (to 9 ft.) extinct flightless bird of Madagascar
- Aerobacter aerogenes
- a species of Gram-negative aerobic bacteria that produce gas and acid from sugars and are sometimes involved in the souring of milk
- aerobe
- an organism (especially a bacterium) that requires air or free oxygen for life
- Aetobatus narinari
- ray with back covered with white or yellow spots; widely distributed in warm seas
- affenpinscher
- European breed of small dog resembling a terrier with dark wiry hair and a tufted muzzle
- Affirmed
- thoroughbred that won the triple crown in 1978
- Afghan hound
- tall graceful breed of hound with a long silky coat; native to the Near East
- African clawed frog
- a tongueless frog native to Africa; established in the United States as result of release of laboratory and aquarium animals
- African hunting dog
- a powerful doglike mammal of southern and eastern Africa that hunts in large packs; now rare in settled area
- African wild ass
- a wild ass of Africa
- Africander
- tall large-horned humped cattle of South Africa; used for meat or draft
- Afropavo congensis
- both sexes are brightly colored
- aftershaft
- a supplementary feather (usually small) on the underside of the base of the shaft of some feathers in some birds
- agama
- small terrestrial lizard of warm regions of the Old World
- agamid
- a lizard of the family Agamidae
- Agelaius phoeniceus
- North American blackbird with scarlet patches on the wings
- Agkistrodon contortrix
- common coppery brown pit viper of upland eastern United States
- Agkistrodon piscivorus
- venomous semiaquatic snake of swamps in southern United States
- agnathan
- eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms
- Agonus cataphractus
- northern Atlantic sea poacher
- Agriocharis ocellata
- wild turkey of Central America and northern South America
- Agrobacterium tumefaciens
- the bacteria that produce crown gall disease in plants
- Ailuropoda melanoleuca
- large black-and-white herbivorous mammal of bamboo forests of China and Tibet; in some classifications considered a member of the bear family or of a separate family Ailuropodidae
- Ailurus fulgens
- reddish-brown Old World raccoon-like carnivore; in some classifications considered unrelated to the giant pandas
- air bladder
- an air-filled sac near the spinal column in many fishes that helps maintain buoyancy
- air sac
- any of the membranous air-filled extensions of the lungs of birds
- air sac
- any of the thin-walled extensions of the tracheae of insects
- Airedale terrier
- breed of large wiry-coated terrier bred in Yorkshire
- Aix galericulata
- showy crested Asiatic duck; often domesticated
- Aix sponsa
- showy North American duck that nests in hollow trees
- Ajaia ajaja
- tropical rose-colored New World spoonbill
- ala
- a wing of an insect
- Alaskan malamute
- breed of sled dog developed in Alaska
- Alauda arvensis
- brown-speckled European lark noted for singing while hovering at a great height
- albatross
- large web-footed birds of the southern hemisphere having long narrow wings; noted for powerful gliding flight
- Albula vulpes
- slender silvery marine fish found in tropical mud flats and mangrove lagoons
- Alca torda
- black-and-white northern Atlantic auk having a compressed sharp-edged bill
- Alces alces
- large northern deer with enormous flattened antlers in the male; called `elk' in Europe and `moose' in North America
- Alectis ciliaris
- fish having greatly elongated front rays on dorsal and anal fins
- Alectoris graeca
- of mountainous areas of southern Europe
- Alectoris ruffa
- common western European partridge with red legs
- Alectura lathami
- black megapode of wooded regions of Australia and New Guinea
- alga
- primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves
- Algeripithecus minutus
- tiny (150 to 300 grams) extinct primate of 46 to 50 million years ago; fossils found in Algeria; considered by some authorities the leading candidate for the first anthropoid
- allantois
- the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)
- alley cat
- a homeless cat
- alligator lizard
- slim short-limbed lizard having a distinctive fold on each side that permits expansion; of western North America
- Alligator mississipiensis
- large alligator of the southeastern United States
- Alligator sinensis
- small alligator of the Yangtze valley of China having unwebbed digits
- alligator
- either of two amphibious reptiles related to crocodiles but with shorter broader snouts
- allosaur
- late Jurassic carnivorous dinosaur; similar to but somewhat smaller than tyrannosaurus
- Alopex lagopus
- thickly-furred fox of Arctic regions; brownish in summer and white in winter
- Alopius vulpinus
- large pelagic shark of warm seas with a whiplike tail used to round up small fish on which to feed
- Alosa alosa
- European shad
- Alosa chrysocloris
- shad that spawns in streams of the Mississippi drainage; very similar to Alosa sapidissima
- alphavirus
- an arbovirus of the family Togaviridae that can cause a variety of encephalitis in horses
- Alsophila pometaria
- North American moth with grey-winged males and wingless females; larvae are fall cankerworms
- alula
- tuft of small stiff feathers on the first digit of a bird's wing
- alula
- scalelike structure between the base of the wing and the halter of a two-winged fly
- Alytes cisternasi
- similar in habit to Alytes obstetricians
- Alytes obstetricans
- European toad whose male carries the fertilized eggs wrapped around its hind legs until they hatch
- amadavat
- red Asian weaverbirds often kept as cage birds
- amazon
- mainly green tropical American parrots
- amberfish
- any of several amber to coppery fork-tailed warm-water carangid fishes
- Ambloplites rupestris
- game and food fish of upper Mississippi and Great Lakes
- Amblyrhynchus cristatus
- shore-dwelling seaweed-eating lizard of the Galapagos Islands
- ambulacrum
- one of the five areas on the undersurface of an echinoderm on which the tube feet are located
- Ambystoma maculatum
- glossy black North American salamander with yellow spots
- Ambystoma mexicanum
- larval salamander of mountain lakes of Mexico that usually lives without metamorphosing
- Ambystoma talpoideum
- brownish-black burrowing salamander of southeastern United States
- Ambystoma tigrinum
- widely distributed brown or black North American salamander with vertical yellowish blotches
- ambystomid
- small to moderate-sized terrestrial or semiaquatic New World salamander
- ameba
- naked freshwater or marine or parasitic protozoa that form temporary pseudopods for feeding and locomotion
- Ameiurus Melas
- catfish common in eastern United States
- American badger
- a variety of badger native to America
- American buffalo
- large shaggy-haired brown bison of North American plains
- American crayfish
- common large crayfishes of eastern North America
- American egret
- a common egret of the genus Egretta found in America; it is a variety of the Old World white egret Casmerodius albus
- American flying squirrel
- New World flying squirrels
- American foxhound
- an American breed of foxhounds used for hunting both in packs and individually
- American green toad
- small green or yellow-green toad with small black bars and stripes
- American harvest mouse
- any of several small greyish New World mice inhabiting e.g. grain fields
- American mastodont
- mastodon of North America; in some classifications considered a mammoth rather than a mastodon
- American saddle horse
- a high-stepping horse originating in Kentucky
- American smooth dogfish
- found along the Atlantic coast of the Americas
- American Staffordshire terrier
- American breed of muscular terriers with a short close-lying stiff coat
- American water ouzel
- a water ouzel of western North America
- American water shrew
- water shrew of North America
- American water spaniel
- breed of medium-sized spaniels originating in America having chocolate or liver-colored curly coat
- American widgeon
- a widgeon the male of which has a white crown
- American woodcock
- small long-billed woodcock; prized as a game bird
- amethystine python
- a python having the color of amethyst
- Amia calva
- primitive long-bodied carnivorous freshwater fish with a very long dorsal fin; found in sluggish waters of North America
- Ammotragus lervia
- wild sheep of northern Africa
- amnion
- thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals)
- Amniota
- higher vertebrates (reptiles, birds and mammals) possessing an amnion during development
- amniote
- any member of the Amniota
- amphibian
- cold-blooded vertebrate typically living on land but breeding in water; aquatic larvae undergo metamorphosis into adult form
- amphibian family
- any family of amphibians
- amphibian genus
- any genus of amphibians
- amphidiploid
- (genetics) an organism or cell having a diploid set of chromosomes from each parent
- amphioxus
- small translucent lancet-shaped burrowing marine animal; primitive forerunner of the vertebrates
- amphipod
- a kind of malacostracan crustacean
- Amphiprion percula
- an anemone fish of the genus Amphiprion
- amphiuma
- aquatic eel-shaped salamander having two pairs of very small feet; of still muddy waters in the southern United States
- Anabas testudineus
- a small perch of India whose gills are modified to allow it to breathe air; has spiny pectoral fins that enable it to travel on land
- Anabrus simplex
- large dark wingless cricket-like katydid of arid parts of western United States
- anaerobe
- an organism (especially a bacterium) that does not require air or free oxygen to live
- anapsid
- primitive reptile having no opening in the temporal region of the skull; all extinct except turtles
- Anas acuta
- long-necked river duck of the Old and New Worlds having elongated central tail feathers
- Anas clypeata
- freshwater duck of the northern hemisphere having a broad flat bill
- Anas crecca
- common teal of Eurasia and North America
- Anas discors
- American teal
- Anas penelope
- freshwater duck of Eurasia and northern Africa related to mallards and teals
- Anas platyrhynchos
- wild dabbling duck from which domestic ducks are descended; widely distributed
- Anas querquedula
- small Eurasian teal
- Anas rubripes
- a dusky duck of northeastern United States and Canada
- Anasa tristis
- large black American bug that sucks sap of vines of the gourd family
- anaspid
- extinct small freshwater jawless fish usually having a heterocercal tail and an armored head; of the Silurian and Devonian
- anatotitan
- one of the largest and most famous duck-billed dinosaurs
- anchovy
- small herring-like plankton-eating fishes often canned whole or as paste; abundant in tropical waters worldwide
- Ancylus fluviatilis
- minute conical gastropod superficially resembling a limpet but living and feeding on freshwater plants
- andrena
- a bee that is a member of the genus Andrena
- Aneides lugubris
- yellow-spotted brown salamander of California woodlands
- anemone fish
- live associated with sea anemones
- anemone
- marine polyps that resemble flowers but have oral rings of tentacles; differ from corals in forming no hard skeleton
- angelfish
- a butterfly fish of the genus Pomacanthus
- anglewing
- nymphalid butterfly having angular notches on the outer edges of the forewings
- angleworm
- terrestrial worm that burrows into and helps aerate soil; often surfaces when the ground is cool or wet; used as bait by anglers
- Angora cat
- a long-haired breed of cat similar to the Persian cat
- Angora goat
- a domestic breed of goat raised for its long silky hair which is the true mohair
- Angora rabbit
- domestic breed of rabbit with long white silky hair
- anguid lizard
- any of a small family of lizards widely distributed in warm areas; all are harmless and useful as destroyers of e.g. slugs and insects
- Anguilla sucklandii
- New Zealand eel
- Anguillula aceti
- minute eelworm that feeds on organisms that cause fermentation in e.g. vinegar
- Anguis fragilis
- small burrowing legless European lizard with tiny eyes; popularly believed to be blind
- Anhima cornuta
- screamer having a hornlike process projecting from the forehead
- Anhinga anhinga
- blackish New World snakebird of swampy regions
- anhinga
- fish-eating bird of warm inland waters having a long flexible neck and slender sharp-pointed bill
- ani
- black tropical American cuckoo
- animal foot
- the pedal extremity of vertebrates other than human beings
- animal leg
- the leg of an animal
- animal order
- the order of animals
- animal virus
- an animal pathogen that is a virus
- animalcule
- microscopic organism such as an amoeba or paramecium
- Anisotremus surinamensis
- dusky grey food fish found from Louisiana and Florida southward
- Anisotremus virginicus
- black and gold grunt found from Bermuda to Caribbean to Brazil
- ankylosaur
- having the back covered with thick bony plates; thought to have walked with a sprawling gait resembling a lizard's
- annelid
- worms with cylindrical bodies segmented both internally and externally
- Anoa depressicornis
- small buffalo of the Celebes having small straight horns
- Anolis carolinensis
- small arboreal tropical American insectivorous lizards with the ability to change skin color
- Anomala orientalis
- introduced into United States from the Orient; larvae feed on roots of sugarcane and other grasses
- anomalops
- fish having a luminous organ beneath eye; of warm waters of the western Pacific and Puerto Rico
- Anomalopteryx oweni
- the smallest moa; slender moa about the size of a large turkey
- Anomia ephippium
- thin-shelled bivalve having the right valve deeply notched
- anopheline
- any mosquito of the genus Anopheles
- Anoplophora glabripennis
- a beetle from China that has been found in the United States and is a threat to hardwood trees; lives inside the tree; no natural predators in the United States
- Anser anser
- common grey wild goose of Europe; ancestor of many domestic breeds
- Anser cygnoides
- very large wild goose of northeast Asia; interbreeds freely with the greylag
- anseriform bird
- chiefly web-footed swimming birds
- ant bird
- any of various dull-colored South American birds that feeding on ants some following army ant swarms
- ant cow
- excretes a honeylike substance eaten by ants
- ant lion
- winged insect resembling a dragonfly; the larvae (doodlebugs) dig conical pits where they wait to catch e.g. ants
- ant lion
- the larva of any of several insects
- ant shrike
- antbirds superficially resembling shrikes
- ant thrush
- a kind of antbird
- ant
- social insect living in organized colonies; characteristically the males and fertile queen have wings during breeding season; wingless sterile females are the workers
- anteater
- a burrowing monotreme mammal covered with spines and having a long snout and claws for hunting ants and termites; native to New Guinea
- anteater
- a burrowing monotreme mammal covered with spines and having a long snout and claws for hunting ants and termites; native to Australia
- anteater
- toothless mammal of southern Africa and Asia having a body covered with horny scales and a long snout for feeding on ants and termites
- antelope
- graceful Old World ruminant with long legs and horns directed upward and backward; includes gazelles; springboks; impalas; addax; gerenuks; blackbucks; dik-diks
- antenna
- one of a pair of mobile appendages on the head of e.g. insects and crustaceans; typically sensitive to touch and taste
- Antheraea mylitta
- oriental moth that produces brownish silk
- Antheraea pernyi
- a Chinese moth that produces a brownish silk
- Antheraea polyphemus
- very large yellowish-brown American silkworm moth with large eyespots on hind wings; larvae feed on fruit and shade trees
- Anthonomus grandis
- greyish weevil that lays its eggs in cotton bolls destroying the cotton
- Anthrenus scrophulariae
- a small black and red and white carpet beetle
- anthropoid
- any member of the suborder Anthropoidea including monkeys and apes and hominids
- anthropoid ape
- any tailless ape of the families Pongidae and Hylobatidae
- Anthus pratensis
- a common pipit that is brown above and white below; widely distributed in northern and central Europe and in Asia
- Antidorcas marsupialis
- a South African gazelle noted for springing lightly into the air
- Antilocapra americana
- fleet antelope-like ruminant of western North American plains with small branched horns
- Antilope cervicapra
- common Indian antelope with a dark back and spiral horns
- antler
- deciduous horn of a member of the deer family
- Antrozous pallidus
- drab yellowish big-eared bat that lives in caves
- anuran
- any of various tailless stout-bodied amphibians with long hind limbs for leaping; semiaquatic and terrestrial species
- Aotus trivirgatus
- nocturnal monkey of Central America and South America with large eyes and thick fur
- Apatosaurus excelsus
- huge quadrupedal herbivorous dinosaur common in North America in the late Jurassic
- Apatura iris
- large European butterfly the male of which has wings shaded with purple
- ape
- any of various primates with short tails or no tail at all
- aphid
- any of various small plant-sucking insects
- aphid lion
- carnivorous larva of lacewing flies
- Aphis fabae
- blackish aphid that infests e.g. beans and sugar beets
- Aphis pomi
- bright green aphid; feeds on and causes curling of apple leaves
- Aphriza virgata
- sandpiper-like shorebird of Pacific coasts of North America and South America
- Aphrophora saratogensis
- feeds on pines in northern United States
- Apis mellifera
- social bee often domesticated for the honey it produces
- Apis mellifera scutellata
- a strain of bees that originated in Brazil in the 1950s as a cross between an aggressive African bee and a honeybee; retains most of the traits of the African bee; now spread as far north as Texas
- aplacophoran
- deep-water wormlike mollusks lacking calcareous plates on the body but having fine slimy spicules on the covering mantle
- Aplodontia rufa
- bulky nocturnal burrowing rodent of uplands of the Pacific coast of North America; the most primitive living rodent
- Aplysia punctata
- naked marine gastropod having a soft body with reduced internal shell and two pairs of ear-like tentacles
- apodeme
- ridge-like ingrowth of the exoskeleton of an arthropod that supports internal organs and provides attachment points for muscles
- apodiform bird
- nonpasserine bird having long wings and weak feet; spends much of its time in flight
- Apogon maculatus
- a cardinalfish found in tropical Atlantic coastal waters
- apolemia
- large siphonophore of up to 50 ft long
- Appaloosa
- a hardy breed of saddle horse developed in western North America and characteristically having a spotted rump
- appendicularia
- free-swimming tadpole-shaped pelagic tunicate resembling larvae of other tunicates
- Appenzeller
- a smaller of the four Swiss breeds
- Aptenodytes forsteri
- the largest penguin; an Antarctic penguin
- Aptenodytes patagonica
- large penguin on islands bordering the Antarctic Circle
- apteryx
- nocturnal flightless bird of New Zealand having a long neck and stout legs; only surviving representative of the order Apterygiformes
- aquatic bird
- wading and swimming and diving birds of either fresh or salt water
- aquatic mammal
- whales and dolphins; manatees and dugongs; walruses; seals
- aquatic vertebrate
- animal living wholly or chiefly in or on water
- Aquila chrysaetos
- large eagle of mountainous regions of the northern hemisphere having a golden-brown head and neck
- Aquila rapax
- brownish eagle of Africa and parts of Asia
- Arabian
- a spirited graceful and intelligent riding horse native to Arabia
- arachnid
- air-breathing arthropods characterized by simple eyes and four pairs of legs
- arame
- an edible seaweed with a mild flavor
- Aramus guarauna
- wading bird of South America and Central America
- Aramus pictus
- wading bird of Florida, Cuba and Jamaica having a drooping bill and a distinctive wailing call
- Aranea diademata
- a spider common in European gardens
- Araneus cavaticus
- an orange and tan spider with darkly banded legs that spins an orb web daily
- arborvirus
- a large heterogeneous group of RNA viruses divisible into groups on the basis of the virions; they have been recovered from arthropods, bats, and rodents; most are borne by arthropods; they are linked by the epidemiologic concept of transmission between vertebrate hosts by arthropod vectors (mosquitoes, ticks, sandflies, midges, etc.) that feed on blood; they can cause mild fevers, hepatitis, hemorrhagic fever, and encephalitis
- arcella
- an amoeba-like protozoan with a chitinous shell resembling an umbrella
- archaebacteria
- considered ancient life forms that evolved separately from bacteria and blue-green algae
- Archaeopteryx lithographica
- extinct primitive toothed bird of the Jurassic period having a long feathered tail and hollow bones; usually considered the most primitive of all birds
- archaeornis
- extinct primitive toothed bird with a long feathered tail and three free clawed digits on each wing
- archenteron
- central cavity of the gastrula; becomes the intestinal or digestive cavity
- archiannelid
- small primitive marine worm lacking external segmentation and resembling polychaete larvae
- Archidiskidon imperator
- largest known mammoth; of America
- Archilochus colubris
- a kind of hummingbird
- architeuthis
- largest mollusk known about but never seen (to 60 feet long)
- Archosargus probatocephalus
- large (up to 20 lbs) food fish of the eastern coast of the United States and Mexico
- Archosargus rhomboidalis
- sea bream of warm Atlantic waters
- archosaur
- extinct reptiles including: dinosaurs; plesiosaurs; pterosaurs; ichthyosaurs; thecodonts
- Arctic ground squirrel
- large ground squirrel of the North American far north
- Arctictis bintourong
- arboreal civet of Asia having a long prehensile tail and shaggy black hair
- arctiid
- stout-bodied broad-winged moth with conspicuously striped or spotted wings; larvae are hairy caterpillars
- Arctocebus calabarensis
- a kind of lemur
- Arctocephalus philippi
- a fur seal of the Pacific coast of California and southward
- Arctonyx collaris
- southeast Asian badger with a snout like a pig
- Ardea herodius
- large American heron having bluish-grey plumage
- Ardea occidentalis
- large white heron of Florida and the Florida Keys
- Arenaria interpres
- common Arctic turnstone that winters in South America and Australia
- Arenaria-Melanocephala
- common turnstone of the Pacific coast of North America
- Arenaviridae
- a family of arborviruses carried by arthropods
- arenavirus
- animal viruses belonging to the family Arenaviridae
- argasid
- tick lacking a dorsal shield and having mouth parts on the under side of the head
- argentine
- any of various small silver-scaled salmon-like marine fishes
- argentinosaur
- huge herbivorous dinosaur of Cretaceous found in Argentina
- Argiope aurantia
- a widely distributed North American garden spider
- Argonauta argo
- cephalopod mollusk of warm seas whose females have delicate papery spiral shells
- argus
- large brilliantly patterned East Indian pheasant
- Argyrotaenia citrana
- California moth whose larvae live in especially oranges
- Arilus cristatus
- large predatory North American bug that sucks the blood of other insects
- arista
- bristlelike process near the tip of the antenna of certain flies
- Arizona elegans
- nocturnal burrowing snake of western United States with shiny tan scales
- ark shell
- marine bivalve mollusk having a heavy toothed shell with a deep boat-like inner surface
- Arkansas kingbird
- a kingbird seen in western United States; head and back are pale grey and the breast is yellowish and the tail is black
- armadillo
- burrowing chiefly nocturnal mammal with body covered with strong horny plates
- armor
- tough more-or-less rigid protective covering of an animal or plant
- armored catfish
- South American catfish having the body covered with bony plates
- armored dinosaur
- dinosaurs having bony armour
- armored scale
- insect having a firm covering of wax especially in the female
- army ant
- tropical nomadic ant that preys mainly on other insects
- armyworm
- larva of fungus gnat that feed on cereals and other grains; they march in large companies in regular order when the food is exhausted
- arrowworm
- any worm of the Chaetognatha; transparent marine worm with horizontal lateral and caudal fins and a row of movable curved spines at each side of the mouth
- Artemia salina
- common to saline lakes
- arthropod
- invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin
- arthropod family
- any of the arthropods
- arthropod genus
- a genus of arthropods
- artiodactyl
- placental mammal having hooves with an even number of functional toes on each foot
- Arvicola amphibius
- common large Eurasian vole
- Ascaphus trui
- western North American frog with a taillike copulatory organ
- Ascaridia galli
- intestinal parasite of domestic fowl
- Ascaris lumbricoides
- intestinal parasite of humans and pigs
- ascidian
- minute sedentary marine invertebrate having a saclike body with siphons through which water enters and leaves
- ascidian tadpole
- free-swimming larva of ascidians; they have a tail like a tadpole that contains the notochord
- Ascophyllum nodosum
- similar to and found with black rockweed
- Asian coral snake
- of India
- Asian horseshoe crab
- horseshoe crab of the coast of eastern Asia
- Asian tiger mosquito
- striped native of Japan thriving in southwestern and midwestern United States and spreading to the Caribbean; potential carrier of serious diseases
- Asian wild ox
- genus of Asiatic wild oxen
- Asiatic flying squirrel
- nocturnal rodent of Asia having furry folds of skin between forelegs and hind legs enabling it to move by gliding leaps
- Asio otus
- slender European owl of coniferous forests with long ear tufts
- Aspidelaps lubricus
- small widely distributed arboreal snake of southern Africa banded in black and orange
- Aspidiotus perniciosus
- small east Asian insect naturalized in the United States that damages fruit trees
- Aspidophoroides monopterygius
- small very elongate sea poachers
- ass
- hardy and sure-footed animal smaller and with longer ears than the horse
- assassin bug
- a true bug: long-legged predacious bug living mostly on other insects; a few suck blood of mammals
- Assault
- thoroughbred that won the triple crown in 1946
- Astrophyton muricatum
- a variety of basket star
- Astropogon stellatus
- found in West Indies; lives in mantle cavity of a living conch
- Ateles geoffroyi
- arboreal monkey of tropical America with long slender legs and long prehensile tail
- Athene noctua
- small European owl
- Atherinopsis californiensis
- a relatively large silversides of the Pacific coast of North America (known to reach 18 inches in length)
- Atlantic bonito
- medium-sized tuna-like food fish of warm Atlantic and Pacific waters; less valued than tuna
- Atlantic bottlenose dolphin
- the most common dolphin of northern Atlantic and Mediterranean; often kept captive and trained to perform
- Atlantic salmon
- found in northern coastal Atlantic waters or tributaries; adults do not die after spawning
- Atlantic spiny dogfish
- destructive dogfish of the Atlantic coastal waters of America and Europe; widely used in anatomy classes
- attack dog
- a watchdog trained to attack on command
- Atticus atlas
- giant saturniid moth widespread in Asia; sometimes cultured for silk
- auk
- black-and-white short-necked web-footed diving bird of northern seas
- auklet
- any of several small auks of the northern Pacific coasts
- Aulostomus maculatus
- tropical Atlantic fish with a long snout; swims snout down
- Auriparus flaviceps
- very small yellow-headed titmouse of western North America
- Australian bonytongue
- a species of large fish found in Australian rivers
- Australian magpie
- black-and-white oscine birds that resemble magpies
- Australian sea lion
- a variety of sea lion found in Australia
- Australian stilt
- long-legged three-toed wading bird of brackish marshes of Australia
- Australian terrier
- small greyish wire-haired breed of terrier from Australia similar to the cairn
- Australian turtledove
- small Australian dove
- australopithecine
- any of several extinct humanlike bipedal primates with relatively small brains of the genus Australopithecus; from 1 to 4 million years ago
- Australopithecus afarensis
- fossils found in Ethiopia; from 3.5 to 4 million years ago
- Australopithecus africanus
- gracile hominid of southern Africa; from about 3 million years ago
- Australopithecus boisei
- large-toothed hominid of eastern Africa; from 1 to 2 million years ago
- Australopithecus robustus
- large-toothed hominid of southern Africa; from 1.5 to 2 million years ago; formerly Paranthropus
- Automeris io
- large yellow American moth having a large eyelike spot on each hind wing; the larvae have stinging spines
- Avahi laniger
- nocturnal indris with thick grey-brown fur and a long tail
- avocet
- long-legged web-footed black-and-white shorebird with slender upward-curving bill
- Ayrshire
- hardy breed of dairy cattle from Ayr, Scotland
- Aythya affinis
- common scaup of North America; males have purplish heads
- Aythya americana
- North American diving duck with a grey-and-black body and reddish-brown head
- Aythya ferina
- heavy-bodied Old World diving duck having a grey-and-black body and reddish head
- Aythya marila
- large scaup of North America having a greenish iridescence on the head of the male
- Aythya valisineria
- North American wild duck valued for sport and food
- B
- aerobic rod-shaped spore-producing bacterium; often occurring in chainlike formations; found primarily in soil
- baa-lamb
- child's word for a sheep or lamb
- babbler
- any of various insectivorous Old World birds with a loud incessant song; in some classifications considered members of the family Muscicapidae
- baboon
- large terrestrial monkeys having doglike muzzles
- baby
- a very young mammal
- baby bird
- young bird not yet fledged
- Babyrousa Babyrussa
- Indonesian wild pig with enormous curved canine teeth
- Bacillus anthracis
- a species of bacillus that causes anthrax in humans and in animals (cattle and swine and sheep and rabbits and mice and guinea pigs); can be used a bioweapon
- Bacillus subtilis
- a species of bacillus found in soil and decomposing organic matter; some strains produce antibiotics
- bacteria family
- a family of bacteria
- bacteria genus
- a genus of bacteria
- bacteria order
- an order of bacteria
- bacteria species
- a species of bacteria
- bacteria
- (microbiology) single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll that reproduce by fission; important as pathogens and for biochemical properties; taxonomy is difficult; often considered to be plants
- bacteriochlorophyll
- a substance in photosensitive bacteria that is related to but different from chlorophyll of higher plants
- bacteriophage
- a virus that is parasitic (reproduces itself) in bacteria
- bacteroid
- a rodlike bacterium (especially any of the rod-shaped or branched bacteria in the root nodules of nitrogen-fixing plants)
- badger
- sturdy carnivorous burrowing mammal with strong claws; widely distributed in the northern hemisphere
- badger dog
- small long-bodied short-legged German breed of dog having a short sleek coat and long drooping ears; suited for following game into burrows
- bag
- mammary gland of bovids (cows and sheep and goats)
- Baiomys taylori
- very small dark greyish brown mouse resembling a house mouse; of Texas and Mexico
- Bairdiella chrysoura
- small silvery drumfish often mistaken for white perch; found along coasts of United States from New York to Mexico
- Balaena mysticetus
- large-mouthed Arctic whale
- Balaeniceps rex
- large stork-like bird of the valley of the White Nile with a broad bill suggesting a wooden shoe
- Balaenoptera acutorostrata
- small finback of coastal waters of Atlantic and Pacific
- Balaenoptera borealis
- similar to but smaller than the finback whale
- Balaenoptera musculus
- largest mammal ever known; bluish-grey migratory whalebone whale mostly of southern hemisphere
- Balaenoptera physalus
- large flat-headed whalebone whale having deep furrows along the throat; of Atlantic and Pacific
- balancer
- either of the rudimentary hind wings of dipterous insects; used for maintaining equilibrium during flight
- Balanus balanoides
- barnacle that attaches to rocks especially in intertidal zones
- baleen whale
- whale with plates of whalebone along the upper jaw for filtering plankton from the water
- Balistes vetula
- tropical Atlantic fish
- banana quit
- any of several honeycreepers
- banded gecko
- any of several geckos with dark bands across the body and differing from typical geckos in having movable eyelids; of United States southwest and Florida Gulf Coast
- bandicoot
- any of various agile ratlike terrestrial marsupials of Australia and adjacent islands; insectivorous and herbivorous
- bandicoot rat
- burrowing scaly-tailed rat of India and Ceylon
- bangtail
- a horse bred for racing
- Bankia setaceae
- giant shipworm of the Pacific coast of North America
- bantam
- any of various small breeds of fowl
- barb
- one of the parallel filaments projecting from the main shaft of a feather
- barbel
- slender tactile process on the jaws of a fish
- barbet
- small brightly colored stout-billed tropical bird having short weak wings
- bark beetle
- small beetle that bores tunnels in the bark and wood of trees; related to weevils
- bark louse
- any of several insects living on the bark of plants
- barker
- informal terms for dogs
- barking deer
- small Asian deer with small antlers and a cry like a bark
- barnacle
- marine crustaceans with feathery food-catching appendages; free-swimming as larvae; as adults form a hard shell and live attached to submerged surfaces
- barosaur
- a dinosaur that could grow to be as tall as a building five stories tall
- barracouta
- a large marine food fish common on the coasts of Australia, New Zealand, and southern Africa
- barracuda
- any voracious marine fish of the genus Sphyraena having an elongated cylindrical body and large mouth with projecting lower jaw and long strong teeth
- Bartramian sandpiper
- large plover-like sandpiper of North American fields and uplands
- basenji
- small smooth-haired breed of African origin having a tightly curled tail and the inability to bark
- basilisk
- small crested arboreal lizard able to run on its hind legs; of tropical America
- basket fish
- any starfish-like animal of the genera Euryale or Astrophyton or Gorgonocephalus having slender complexly branched interlacing arms radiating from a central disc
- bass
- nontechnical name for any of numerous edible marine and freshwater spiny-finned fishes
- Bassariscus astutus
- raccoon-like omnivorous mammal of Mexico and the southwestern United States having a long bushy tail with black and white rings
- basset
- smooth-haired breed of hound with short legs and long ears
- bat
- nocturnal mouselike mammal with forelimbs modified to form membranous wings and anatomical adaptations for echolocation by which they navigate
- batfish
- bottom-dweller of warm western Atlantic coastal waters having a flattened scaleless body that crawls about on fleshy pectoral and pelvic fins
- bay
- a horse of a moderate reddish-brown color
- beach flea
- small amphipod crustaceans that hop like fleas; common on ocean beaches
- beagle
- a small short-legged smooth-coated breed of hound
- beak
- beaklike mouth of animals other than birds (e.g., turtles)
- beak
- horny projecting mouth of a bird
- beaked whale
- any of several whales inhabiting all oceans and having beaklike jaws with vestigial teeth in the upper jaw
- bear
- massive plantigrade carnivorous or omnivorous mammals with long shaggy coats and strong claws
- bear claw
- claw of a bear; often used in jewelry
- bear cub
- a young bear
- beard
- hairy growth on or near the face of certain mammals
- beard worm
- slender animal with tentacles and a tubelike outer covering; lives on the deep ocean bottom
- beard
- tuft of strong filaments by which e.g. a mussel makes itself fast to a fixed surface
- beast of burden
- an animal such as a donkey or ox or elephant used for transporting loads or doing other heavy work
- beaver
- large semiaquatic rodent with webbed hind feet and a broad flat tail; construct complex dams and underwater lodges
- beaver rat
- amphibious rat of Australia and New Guinea
- Bedlington terrier
- a light terrier groomed to resemble a lamb
- bee
- any of numerous hairy-bodied insects including social and solitary species
- bee beetle
- European beetle; infests beehives
- bee eater
- colorful chiefly tropical Old World bird having a strong graceful flight; feeds on especially bees
- bee fly
- hairy nectar-eating fly that resembles a bee; larvae are parasitic on larvae of bees and related insects
- bee killer
- swift predatory fly having a strong body like a bee with the proboscis hardened for sucking juices of other insects captured on the wing
- beef
- cattle that are reared for their meat
- beefalo
- hardy breed of cattle resulting from crossing domestic cattle with the American buffalo; yields leaner beef than conventional breeds
- beetle
- insect having biting mouthparts and front wings modified to form horny covers overlying the membranous rear wings
- belemnite
- a conical calcareous fossil tapering to a point at one end and with a conical cavity at the other end containing (when unbroken) a small chambered phragmocone from the shell of any of numerous extinct cephalopods of the family Belemnitidae
- Belgian hare
- red breed of domestic rabbits; hybrid between Old World rabbit and hare
- Belgian shepherd
- hardy working dog developed in Belgium for herding sheep
- bell magpie
- bluish black fruit-eating bird with a bell-like call
- bellbird
- any of several tropical American birds of the genus Procnias having a bell-like call
- bellows fish
- small bottom-dwelling fish of warm seas having a compressed body and a long snout with a toothless mouth
- bellwether
- sheep that leads the herd often wearing a bell
- belly
- the underpart of the body of certain vertebrates such as snakes or fish
- Bemisia tabaci
- a strain of pest accidentally imported into Florida from the Middle East then spread to California where it is a very serious pest feeding on almost all vegetable crops and poinsettias
- Bengal tiger
- southern short-haired tiger
- Bernese mountain dog
- large powerful long-haired black-coated Swiss dog with deep tan or russet markings on legs and white blaze and feet and chest marking; formerly used for draft
- beroe
- delicately iridescent thimble-shaped ctenophores
- bettong
- short-nosed rat kangaroo
- Bibos frontalis
- ox of southeast Asia sometimes considered a domesticated breed of the gaur
- Bibos gaurus
- wild ox of mountainous areas of eastern India
- biddy
- young bird especially of domestic fowl
- biddy
- adult female chicken
- big bedbug
- large bloodsucking bug
- big cat
- any of several large cats typically able to roar and living in the wild
- big game
- large animals that are hunted for sport
- bigeye
- red fishes of American coastal tropical waters having very large eyes and rough scales
- billfish
- giant warm-water game fish having a prolonged and rounded toothless upper jaw
- billfish
- elongate European surface-dwelling predacious fishes with long toothed jaws; abundant in coastal waters
- billy
- male goat
- biped
- an animal with two feet
- biplane flying fish
- having both pectoral and pelvic fins enlarged
- bird
- warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings
- bird dog
- a gun dog trained to locate or retrieve birds
- bird family
- a family of warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings
- bird genus
- a genus of birds
- bird louse
- wingless insect with mouth parts adapted for biting; mostly parasitic on birds
- bird of Jove
- any of various large keen-sighted diurnal birds of prey noted for their broad wings and strong soaring flight
- bird of Juno
- very large terrestrial southeast Asian pheasant often raised as an ornamental bird
- bird of Minerva
- nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes
- bird of paradise
- any of numerous brilliantly colored plumed birds of the New Guinea area
- bird of passage
- any bird that migrates seasonally
- bird of prey
- any of numerous carnivorous birds that hunt and kill other animals
- bird's foot
- the foot of a bird
- bird-footed dinosaur
- any of numerous carnivorous dinosaurs of the Triassic to Cretaceous with short forelimbs that walked or ran on strong hind legs
- bison
- any of several large humped bovids having shaggy manes and large heads and short horns
- Bison bonasus
- European bison having a smaller and higher head than the North American bison
- bitch
- female of any member of the dog family
- biting midge
- minute two-winged insect that sucks the blood of mammals and birds and other insects
- Bitis arietans
- large African viper that inflates its body when alarmed
- Bitis gabonica
- large heavy-bodied brilliantly marked and extremely venomous west African viper
- bittern
- relatively small compact tawny-brown heron with nocturnal habits and a booming cry; found in marshes
- bivalve
- marine or freshwater mollusks having a soft body with platelike gills enclosed within two shells hinged together
- black bass
- widely distributed and highly prized American freshwater game fishes (sunfish family)
- black carpet beetle
- a carpet beetle that is solid black in color
- black cock
- male black grouse
- black fly
- small blackish stout-bodied biting fly having aquatic larvae; sucks the blood of birds as well as humans and other mammals
- black fox
- red fox in the color phase when its pelt is mostly black
- black grouse
- grouse of which the male is bluish-black
- black sheep
- sheep with a black coat
- black squirrel
- fox squirrel or grey squirrel in the black color phase
- black-and-tan coonhound
- American breed of large powerful hound dogs used for hunting raccoons and other game
- black-headed snake
- small secretive ground-living snake; found from central United States to Argentina
- Blackburnian warbler
- black-and-white North American wood warbler having an orange-and-black head and throat
- blackfish
- female salmon that has recently spawned
- bladder worm
- encysted saclike larva of the tapeworm
- blanquillo
- important marine food fishes
- Blarina brevicauda
- North American shrew with tail less than half its body length
- blastocele
- the fluid-filled cavity inside a blastula
- blastocyst
- the blastula of a placental mammal in which some differentiation of cells has occurred
- blastoderm
- a layer of cells on the inside of the blastula
- blastomere
- any cell resulting from cleavage of a fertilized egg
- blastopore
- the opening into the archenteron
- blastosphere
- early stage of an embryo produced by cleavage of an ovum; a liquid-filled sphere whose wall is composed of a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus occurs
- Blatta orientalis
- dark brown cockroach originally from orient now nearly cosmopolitan in distribution
- Blattella germanica
- small light-brown cockroach brought to United States from Europe; a common household pest
- Blenheim spaniel
- red-and-white variety of English toy spaniel
- blennioid
- elongated mostly scaleless marine fishes with large pectoral fins and reduced pelvic fins
- Blennius pholis
- European scaleless blenny
- blenny
- small usually scaleless fishes with comb-like teeth living about rocky shores; are territorial and live in holes between rocks
- blind snake
- wormlike burrowing snake of warm regions having vestigial eyes
- blindworm
- any of the small slender limbless burrowing wormlike amphibians of the order Gymnophiona; inhabit moist soil in tropical regions
- Blissus leucopterus
- small black-and-white insect that feeds on cereal grasses
- blister beetle
- beetle that produces a secretion that blisters the skin
- blood clam
- red-blooded clam
- blood fluke
- flatworms parasitic in the blood vessels of mammals
- bloodhound
- a breed of large powerful hound of European origin having very acute smell and used in tracking
- bloodsucker
- carnivorous or bloodsucking aquatic or terrestrial worms typically having a sucker at each end
- bloodworm
- a segmented marine worm with bright red body; often used for bait
- blow fly
- large usually hairy metallic blue or green fly; lays eggs in carrion or dung or wounds
- blower
- large aquatic carnivorous mammal with fin-like forelimbs no hind limbs, including: whales; dolphins; porpoises; narwhals
- blowfish
- any of numerous marine fishes whose elongated spiny body can inflate itself with water or air to form a globe; several species contain a potent nerve poison; closely related to spiny puffers
- blue
- any of numerous small butterflies of the family Lycaenidae
- blue cat
- a large catfish of the Mississippi valley
- blue fox
- a variety of Arctic fox having a pale grey winter coat
- blue point Siamese
- Siamese cat having a bluish cream-colored body and dark grey points
- blue point
- small edible oyster typically from the southern shore of Long Island
- blue-green algae
- predominantly photosynthetic prokaryotic organisms containing a blue pigment in addition to chlorophyll; occur singly or in colonies in diverse habitats; important as phytoplankton
- bluebill
- diving ducks of North America having a bluish-grey bill
- bluebird
- blue North American songbird
- bluebird
- fruit-eating mostly brilliant blue songbird of the East Indies
- bluetick
- a very fast American hound; white mottled with bluish grey
- boa
- any of several chiefly tropical constrictors with vestigial hind limbs
- boar
- an uncastrated male hog
- boarfish
- fish with large eyes and long snouts
- boarhound
- large hound used in hunting wild boars
- boat bug
- carnivorous aquatic bug having paddle-like hind legs
- boatswain bird
- mostly white web-footed tropical seabird often found far from land
- bob
- a short or shortened tail of certain animals
- bobwhite
- a popular North American game bird; named for its call
- bollworm
- any of various moth caterpillars that destroy cotton bolls
- bombardier beetle
- beetle that ejects audibly a pungent vapor when disturbed
- Bombina bombina
- toad of central and eastern Europe having red or orange patches mixed with black on its underside
- bombycid
- moderate-sized Asiatic moth whose larvae feed on mulberry leaves and produce silk
- Bombycilla
- waxwings
- Bombycilla cedrorun
- widely distributed over temperate North America
- Bombycilla garrulus
- large waxwing of northern North America; similar to but larger than the cedar waxwing
- Bombyx mori
- stocky creamy-white Asiatic moth found almost entirely under human care; the source of most of the silk commerce
- Bonasa umbellus
- valued as a game bird in eastern United States and Canada
- bone-headed dinosaur
- bipedal herbivorous dinosaurs with bony crowns
- bonito
- any of various scombroid fishes intermediate in size and characteristics between mackerels and tunas
- bonxie
- gull-like jaeger of northern seas
- bony fish
- any fish of the class Osteichthyes
- booby
- small tropical gannet having a bright bill or bright feet or both
- Border collie
- developed in the area between Scotland and England usually having a black coat with white on the head and tip of tail used for herding both sheep and cattle
- Border terrier
- small rough-coated terrier of British origin
- borer
- any of various insects or larvae or mollusks that bore into wood
- borrelia
- cause of e.g. European and African relapsing fever
- Bos banteng
- wild ox of the Malay Archipelago
- Bos grunniens
- large long-haired wild ox of Tibet often domesticated
- Bos indicus
- any of several breeds of Indian cattle; especially a large American heat and tick resistant greyish humped breed evolved in the Gulf States by interbreeding Indian cattle and now used chiefly for crossbreeding
- Bos primigenius
- large recently extinct long-horned European wild ox; considered one of the ancestors of domestic cattle
- Bos taurus
- domesticated bovine animals as a group regardless of sex or age
- Boselaphus tragocamelus
- large Indian antelope; male is blue-grey with white markings; female is brownish with no horns
- Boskop man
- possible early Homo sapiens represented by a cranium found in the Transvaal; formerly considered a separate species
- Boston terrier
- small pug-faced American terrier breed having a smooth brindle or black coat with white markings
- bot
- botfly larva; typically develops inside the body of a horse or sheep or human
- Botaurus lentiginosus
- a kind of bittern
- Botaurus stellaris
- a kind of bittern
- botfly
- stout-bodied hairy dipterous fly whose larvae are parasites on humans and other mammals
- Bothrops atrops
- large extremely venomous pit viper of Central America and South America
- bottlenose
- any of several dolphins with rounded forehead and well-developed beak; chiefly of northern Atlantic and Mediterranean
- bottom fish
- fish that live on the sea bottom (particularly the commercially important gadoid fish like cod and haddock, or flatfish like flounder)
- bottom lurkers
- a fish that lurks on the bottom of a body of water
- bottom-dweller
- a fish that lives and feeds on the bottom of a body of water
- bottom-feeder
- a scavenger that feeds low on the food chain
- Bouviers des Flandres
- rough-coated breed used originally in Belgium for herding and guarding cattle
- bovid
- hollow-horned ruminants
- bovine
- any of various members of the genus Bos
- bowerbird
- any of various birds of the Australian region whose males build ornamented structures resembling bowers in order to attract females
- box tortoise
- chiefly terrestrial turtle of North America; shell can be closed tightly
- boxer
- a breed of stocky medium-sized short-haired dog with a brindled coat and square-jawed muzzle developed in Germany
- boxfish
- any of numerous small tropical fishes having body and head encased in bony plates
- Brabancon griffon
- a variety of Brussels griffon having a short smooth coat
- brachiopod
- marine animal with bivalve shell having a pair of arms bearing tentacles for capturing food; found worldwide
- brachyuran
- typical crabs
- bracketed blenny
- small eellike fishes common in shallow waters of the northern Atlantic
- Bradypus tridactylus
- a sloth that has three long claws on each forefoot and each hindfoot
- brain coral
- massive reef-building coral having a convoluted and furrowed surface
- Brama raii
- deep-bodied sooty-black pelagic spiny-finned fish of the northern Atlantic and northern Pacific; valued for food
- branchia
- respiratory organ of aquatic animals that breathe oxygen dissolved in water
- branchial arch
- one of the bony or cartilaginous arches on each side of the pharynx that support the gills of fishes and aquatic amphibians
- branchial cleft
- one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes
- branchiopod
- aquatic crustaceans typically having a carapace and many pairs of leaflike appendages used for swimming as well as respiration and feeding
- brant
- small dark geese that breed in the north and migrate southward
- Branta bernicla
- the best known variety of brant goose
- Branta canadensis
- common greyish-brown wild goose of North America with a loud, trumpeting call
- Branta leucopsis
- European goose smaller than the brant; breeds in the far north
- Brazilian trumpeter
- trumpeter of Brazil and Guiana; often kept to protect poultry in Brazil
- bream
- any of various usually edible freshwater percoid fishes having compressed bodies and shiny scales; especially (but not exclusively) of the genus Lepomis
- bream
- any of numerous marine percoid fishes especially (but not exclusively) of the family Sparidae
- breast
- the part of an animal's body that corresponds to a person's chest
- Brevoortia tyrannis
- shad-like North American marine fishes used for fish meal and oil and fertilizer
- briard
- old French breed of large strong usually black dogs having a long tail and long wavy and slightly stiff coat
- bristle
- a stiff hair
- bristletail
- small wingless insect with a long bristlelike tail
- brit
- the young of a herring or sprat or similar fish
- brit
- minute crustaceans forming food for right whales
- Brittany spaniel
- tall active short-tailed French breed of bird dog having a usually smooth orange- or liver-and-white coat
- brittle star
- an animal resembling a starfish with fragile whiplike arms radiating from a small central disc
- broadbill
- small birds of the Old World tropics having bright plumage and short wide bills
- broadtail
- hardy coarse-haired sheep of central Asia; lambs are valued for their soft curly black fur
- brocket
- male red deer in its second year
- brocket
- small South American deer with unbranched antlers
- bronc
- an unbroken or imperfectly broken mustang
- brood bitch
- a bitch used for breeding
- brood hen
- a domestic hen ready to brood
- broodmare
- a female horse used for breeding
- Brosme brosme
- large edible marine fish of northern coastal waters; related to cod
- brotula
- deep-sea fishes
- brown algae
- algae having the chlorophyll masked by brown and yellow pigments
- brown bat
- any of numerous medium to small insectivorous bats found worldwide in caves and trees and buildings
- brown bullhead
- freshwater catfish of eastern United States
- brown lacewing
- small dark-colored lacewing fly
- Brown Swiss
- large hardy brown breed of dairy cattle from Switzerland
- Brucella
- an aerobic Gram-negative coccobacillus that causes brucellosis; can be used as a bioweapon
- Bruchus pisorum
- larvae live in and feed on seeds of the pea plant
- bruin
- a conventional name for a bear used in tales following usage in the old epic `Reynard the Fox'
- brush
- a bushy tail or part of a bushy tail (especially of the fox)
- brush kangaroo
- any of various small or medium-sized kangaroos; often brightly colored
- brush-footed butterfly
- medium to large butterflies found worldwide typically having brightly colored wings and much-reduced nonfunctional forelegs carried folded on the breast
- brush-tail porcupine
- porcupine with a tuft of large beaded bristles on the tail
- Brussels griffon
- breed of various very small compact wiry-coated dogs of Belgian origin having a short bearded muzzle
- bryozoan
- sessile aquatic animal forming mossy colonies of small polyps each having a curved or circular ridge bearing tentacles; attach to stones or seaweed and reproduce by budding
- Bubalus bubalis
- an Asian buffalo that is often domesticated for use as a draft animal
- Bubalus mindorensis
- small buffalo of Mindoro in the Philippines
- bubble shell
- marine gastropod mollusk having a very small thin shell
- Bubo virginianus
- brown North American horned owl
- Bubulcus ibis
- small white egret widely distributed in warm regions often found around grazing animals
- Bucephala islandica
- North American goldeneye diving duck
- Bucephela albeola
- small North American diving duck; males have bushy head plumage
- Bucephela clangula
- large-headed swift-flying diving duck of Arctic regions
- buck
- mature male of various mammals (especially deer or antelope)
- bucking bronco
- a wild horse that is vicious and difficult or impossible to break in
- buckskin
- horse of a light yellowish dun color with dark mane and tail
- Budorcas taxicolor
- large heavily built goat antelope of eastern Himalayan area
- buffalo fish
- any of several large suckers of the Mississippi valley
- bufo
- any toad of the genus Bufo
- Bufo americanus
- common toad of America
- Bufo boreas
- of a great variety of habitats from southern Alaska to Baja California west of the Rockies
- Bufo calamita
- common brownish-yellow short-legged toad of western Europe; runs rather than hops
- Bufo marinus
- largest known toad species; native to Central America; valuable destroyer of insect pests
- Bufo microscaphus
- a uniformly warty stocky toad of washes and streams of semiarid southwestern United States
- Bufo speciosus
- nocturnal burrowing toad of mesquite woodland and prairies of the United States southwest
- bug
- general term for any insect or similar creeping or crawling invertebrate
- bug
- a minute life form (especially a disease-causing bacterium); the term is not in technical use
- bug
- insects with sucking mouthparts and forewings thickened and leathery at the base; usually show incomplete metamorphosis
- bulbul
- nightingale spoken of in Persian poetry
- bull
- mature male of various mammals of which the female is called `cow'; e.g. whales or elephants or especially cattle
- bull
- uncastrated adult male of domestic cattle
- bull mastiff
- large powerful breed developed by crossing the bulldog and the mastiff
- bull snake
- any of several large harmless rodent-eating North American burrowing snakes
- bull terrier
- a powerful short-haired terrier originated in England by crossing the bulldog with terriers
- bullbat
- mainly nocturnal North American goatsucker
- bulldog ant
- any of the large fierce Australian ants of the genus Myrmecia
- bullhead
- freshwater sculpin with a large flattened bony-plated head with hornlike spines
- bullhead
- any of several common freshwater catfishes of the United States
- bullock
- young bull
- bullock
- castrated bull
- bumblebee
- robust hairy social bee of temperate regions
- Bungarus fasciatus
- sluggish krait banded with black and yellow
- bunny
- (usually informal) especially a young rabbit
- bunting
- any of numerous seed-eating songbirds of Europe or North America
- Bunyaviridae
- a large family of arboviruses that affect a wide range of hosts (mainly vertebrates and arthropods)
- bunyavirus
- an animal virus belonging to the family Bunyaviridae; can be used as a bioweapon
- Burchell's zebra
- of the plains of central and eastern Africa
- Burhinus oedicnemus
- large-headed large-eyed crepuscular or nocturnal shorebird of the Old World and tropical America having a thickened knee joint
- Burmeisteria retusa
- of southern South America
- Burmese cat
- a short-haired breed with body similar to the Siamese cat but having a solid dark brown or grey coat
- burrfish
- any of several fishes having rigid flattened spines
- burro
- small donkey used as a pack animal
- bush baby
- agile long-tailed nocturnal African lemur with dense woolly fur and large eyes and ears
- bush shrike
- an African shrike
- bush tit
- active grey titmice of western North America
- bustard
- large heavy-bodied chiefly terrestrial game bird capable of powerful swift flight; classified with wading birds but frequents grassy steppes
- bustard quail
- small quail-like terrestrial bird of southern Eurasia and northern Africa that lacks a hind toe; classified with wading birds but inhabits grassy plains
- butcherbird
- large carnivorous Australian bird with the shrike-like habit of impaling prey on thorns
- butcherbird
- shrikes that impale their prey on thorns
- Buteo buteo
- the common European short-winged hawk
- Buteo jamaicensis
- dark brown American hawk species having a reddish-brown tail
- Buteo lagopus
- large hawk of the northern hemisphere that feeds chiefly on small rodents and is beneficial to farmers
- Buteo lineatus
- North American hawk with reddish brown shoulders
- buteonine
- any hawk of the genus Buteo
- butterfish
- small marine fish with a short compressed body and feeble spines
- butterfly
- diurnal insect typically having a slender body with knobbed antennae and broad colorful wings
- butterfly fish
- small usually brilliantly colored tropical marine fishes having narrow deep bodies with large broad fins; found worldwide
- butterfly ray
- a stingray with a short tail and a broad fin
- butterflyfish
- tropical fish with huge fanlike pectoral fins for underwater gliding; unrelated to searobins
- bycatch
- unwanted marine creatures that are caught in the nets while fishing for another species
- Cabassous unicinctus
- naked-tailed armadillo of tropical South America
- cabbage butterfly
- white butterfly whose larvae (cabbageworms) feed on cabbage
- cacique
- black-and-red or black-and-yellow orioles of the American tropics
- cackler
- a hen that has just laid an egg and emits a shrill squawk
- cactus wren
- large harsh-voiced American wren of arid regions of the United States southwest and Mexico
- caddice fly
- small moth-like insect having two pairs of hairy membranous wings and aquatic larvae
- caddisworm
- larva of the caddis fly; constructs a case of silk covered with sand or plant debris
- Cadra cautella
- a moth whose larvae feed on and mat together with webbing various stored products of vegetable origin
- Cadra figulilella
- moth whose larvae attack dried fruits and cereal products
- caiman lizard
- crocodile-like lizard of South America having powerful jaws for crushing snails and mussels
- Caiman sclerops
- caiman with bony ridges about the eyes; found from southern Mexico to Argentina
- caiman
- a semiaquatic reptile of Central and South America that resembles an alligator but has a more heavily armored belly
- Cairina moschata
- large crested wild duck of Central America and South America; widely domesticated
- cairn
- small rough-haired breed of terrier from Scotland
- Calamus penna
- from Florida and Bahamas to Brazil
- calamus
- the hollow spine of a feather
- calf
- young of domestic cattle
- calf
- young of various large placental mammals e.g. whale or giraffe or elephant or buffalo
- calico cat
- a cat having black and cream-colored and yellowish markings
- caliculus
- a small cup-shaped structure (as a taste bud or optic cup or cavity of a coral containing a polyp)
- Calidris canutus
- a sandpiper that breeds in the Arctic and winters in the southern hemisphere
- Calidris Ferruginea
- Old World sandpiper with a curved bill like a curlew
- Calidris melanotos
- American sandpiper that inflates its chest when courting
- California newt
- newt that is similar to Taricha granulosa in characteristics and habitat
- Callimorpha jacobeae
- large red-and-black European moth; larvae feed on leaves of ragwort; introduced into United States to control ragwort
- Callinectes sapidus
- bluish edible crab of Atlantic and Gulf Coasts of North America
- Calliphora vicina
- blowfly with iridescent blue body; makes a loud buzzing noise in flight
- Callisaurus draconoides
- swift lizard with long black-banded tail and long legs; of deserts of United States and Mexico
- Callorhinus ursinus
- of Pacific coast from Alaska southward to California
- calosoma
- any beetle of the genus Calosoma
- Calosoma scrutator
- large metallic blue-green beetle that preys on caterpillars; found in North America
- Calymmatobacterium granulomatis
- the species of bacteria that causes granuloma inguinale
- camel
- cud-chewing mammal used as a draft or saddle animal in desert regions
- Camelus bactrianus
- two-humped camel of the cold deserts of central Asia
- Camelus dromedarius
- one-humped camel of the hot deserts of northern Africa and southwestern Asia
- Campephilus principalis
- large black-and-white woodpecker of southern United States and Cuba having an ivory bill; nearly extinct
- Canachites canadensis
- North American grouse that feeds on evergreen buds and needles
- canary
- any of several small Old World finches
- Cancer borealis
- large red deep-water crab of the eastern coast of North America
- Cancer irroratus
- crab of eastern coast of North America
- Cancer magister
- small edible crab of Pacific coast of North America
- canid
- any of various fissiped mammals with nonretractile claws and typically long muzzles
- Canis aureus
- Old World nocturnal canine mammal closely related to the dog; smaller than a wolf; sometimes hunts in a pack but usually singly or as a member of a pair
- Canis dingo
- wolflike yellowish-brown wild dog of Australia
- Canis familiaris
- a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds
- Canis latrans
- small wolf native to western North America
- Canis lupus
- a wolf with a brindled grey coat living in forested northern regions of North America
- Canis lupus tundrarum
- wolf of Arctic North America having white fur and a black-tipped tail
- Canis rufus
- reddish-grey wolf of southwestern North America
- cankerworm
- green caterpillar of a geometrid moth; pest of various fruit and shade trees
- cannon bone
- greatly developed metatarsal or metacarpal bone in the shank or cannon part of the leg in hoofed mammals
- cannon
- lower part of the leg extending from the hock to the fetlock in hoofed mammals
- capelan
- very small northern fish; forage for sea birds and marine mammals and other fishes
- capon
- castrated male chicken
- Capra aegagrus
- wild goat of Iran and adjacent regions
- Capra falconeri
- large Himalayan goat with large spiraled horns
- Capra hircus
- any of various breeds of goat raised for milk or meat or wool
- Capra ibex
- wild goat of mountain areas of Eurasia and northern Africa having large recurved horns
- Capreolus capreolus
- small graceful deer of Eurasian woodlands having small forked antlers
- caprimulgid
- mainly crepuscular or nocturnal nonpasserine birds with mottled greyish-brown plumage and large eyes; feed on insects
- caprimulgiform bird
- long-winged nonpasserine birds
- Caprimulgus carolinensis
- large whippoorwill-like bird of the southern United States
- Caprimulgus europaeus
- Old World goatsucker
- Caprimulgus vociferus
- American nocturnal goatsucker with grey-and-white plumage
- caprine animal
- any of numerous agile ruminants related to sheep but having a beard and straight horns
- Capros aper
- fish with a projecting snout
- capsid
- the outer covering of protein surrounding the nucleic acid of a virus
- capsid
- a variety of leaf bug
- carabao
- water buffalo of the Philippines
- carabid beetle
- predacious shining black or metallic terrestrial beetle that destroys many injurious insects
- caracara
- any of various long-legged carrion-eating hawks of South America and Central America
- carangid
- a percoid fish of the family Carangidae
- Caranx bartholomaei
- fish of western Atlantic and Gulf of Mexico
- Caranx crysos
- fish of western Atlantic: Cape Cod to Brazil
- Caranx hippos
- fish of western Atlantic and Gulf of Mexico
- carapace
- hard outer covering or case of certain organisms such as arthropods and turtles
- Carassius auratus
- small golden or orange-red freshwater fishes of Eurasia used as pond or aquarium fishes
- Carassius carassius
- European carp closely resembling wild goldfish
- carcase
- the dead body of an animal especially one slaughtered and dressed for food
- Carcharhinus leucas
- a most common shark in temperate and tropical coastal waters worldwide; heavy-bodied and dangerous
- Carcharhinus limbatus
- widely distributed shallow-water shark with fins seemingly dipped in ink
- Carcharhinus obscurus
- relatively slender blue-grey shark; nearly worldwide in tropical and temperate waters
- Carcharhinus plumbeus
- most common grey shark along coasts of middle Atlantic states; sluggish and occasionally caught by fishermen
- Carcharinus longimanus
- large deep-water shark with white-tipped dorsal fin; worldwide distribution; most dangerous shark
- Carcharodon carcharias
- large aggressive shark widespread in warm seas; known to attack humans
- Cardigan Welsh corgi
- slightly bowlegged variety of corgi having rounded ears and a long tail
- cardinalfish
- small red fishes of coral reefs and inshore tropical waters
- Cardium edule
- common edible European cockle
- Carduelis cannabina
- small Old World finch whose male has a red breast and forehead
- Carduelis carduelis
- small European finch having a crimson face and yellow-and-black wings
- Carduelis cucullata
- South American species of scarlet finch with black head and wings and tail
- Carduelis flammea
- small siskin-like finch with a red crown and a rosy breast and rump
- Carduelis hornemanni
- small siskin-like finch with a red crown
- Carduelis spinus
- small yellow-and-black Eurasian finch with a sharp beak
- Caretta caretta
- very large carnivorous sea turtle; wide-ranging in warm open seas
- Cariama cristata
- Brazilian Cariama; sole representative of the genus Cariama
- caribe
- small voraciously carnivorous freshwater fishes of South America that attack and destroy living animals
- carinate
- birds having keeled breastbones for attachment of flight muscles
- Carniolan bee
- greyish highly productive European honeybee that has a quiet disposition
- carnivore
- any animal that feeds on flesh
- carnivore
- a terrestrial or aquatic flesh-eating mammal
- carnivorous bat
- typically having large ears and feeding primarily on insects; worldwide in distribution
- carnosaur
- large carnivorous bipedal dinosaur having huge claws
- carp
- any of various freshwater fish of the family Cyprinidae
- carpenter ant
- ant that nests in decaying wood in which it bores tunnels for depositing eggs
- carpenter bee
- large solitary bee that lays eggs in tunnels bored into wood or plant stems
- carpet beetle
- small beetle whose larvae are household pests feeding on woolen fabrics
- Carphophis amoenus
- small reddish wormlike snake of eastern United States
- Carpocapsa pomonella
- a small grey moth whose larvae live in apples and English walnuts
- Carpodacus mexicanus
- small finch originally of the western United States and Mexico
- Carpodacus purpureus
- North American finch having a raspberry-red head and breast and rump
- carriage dog
- a large breed having a smooth white coat with black or brown spots; originated in Dalmatia
- carrier
- (genetics) an organism that possesses a recessive gene whose effect is masked by a dominant allele; the associated trait is not apparent but can be passed on to offspring
- carrier pigeon
- a homing pigeon used to carry messages
- carrion
- the dead and rotting body of an animal; unfit for human food
- cart horse
- draft horse kept for pulling carts
- cartilaginous fish
- fishes in which the skeleton may be calcified but not ossified
- caseworm
- insect larva that constructs a protective case around its body
- Cashmere goat
- Himalayan goat having a silky undercoat highly prized as cashmere wool
- Casmerodius albus
- widely distributed Old World white egret
- cassowary
- large black flightless bird of Australia and New Guinea having a horny head crest
- Castor canadensis
- a variety of beaver found in almost all areas of North America except Florida
- cat shark
- small bottom-dwelling sharks with cat-like eyes; found along continental slopes
- cat
- feline mammal usually having thick soft fur and no ability to roar: domestic cats; wildcats
- catamount
- short-tailed wildcats with usually tufted ears; valued for their fur
- caterpillar
- a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth
- catfish
- any of numerous mostly freshwater bottom-living fishes of Eurasia and North America with barbels like whiskers around the mouth
- catfish
- large ferocious northern deep-sea food fishes with strong teeth and no pelvic fins
- Catharacta skua
- large brown skua of the northern Atlantic
- Cathartes aura
- a New World vulture that is common in South America and Central America and the southern United States
- Catocala nupta
- moth having dull forewings and red-marked hind wings
- Catoptrophorus semipalmatus
- large North American shorebird of eastern and Gulf Coasts
- catostomid
- a cypriniform fish of the family Catostomidae
- caudal appendage
- tail especially of a mammal posterior to and above the anus
- caudal fin
- the tail of fishes and some other aquatic vertebrates
- caudate
- amphibians that resemble lizards
- cavalry horse
- horse trained for battle
- Cavia cobaya
- stout-bodied nearly tailless domesticated cavy; often kept as a pet and widely used in research
- Cavia porcellus
- South American cavy; possibly ancestral to the domestic guinea pig
- cavy
- short-tailed rough-haired South American rodent
- Cebuella pygmaea
- the smallest monkey; of tropical forests of the Amazon
- Cebus capucinus
- monkey of Central America and South America having thick hair on the head that resembles a monk's cowl
- centipede
- chiefly nocturnal predacious arthropod having a flattened body of 15 to 173 segments each with a pair of legs, the foremost pair being modified as prehensors
- centrarchid
- small carnivorous freshwater percoid fishes of North America usually having a laterally compressed body and metallic luster: crappies; black bass; bluegills; pumpkinseed
- Centrocercus urophasianus
- large grouse of sagebrush regions of North America
- Centropistes striata
- bluish black-striped sea bass of the Atlantic coast of the United States
- Centropristis philadelphica
- a kind of sea bass
- Centropus phasianinus
- Australian bird with a tail like a pheasant
- Centropus sinensis
- common coucal of India and China
- cephalaspid
- extinct jawless fish of the Devonian with armored head
- cephalochordate
- fish-like animals having a notochord rather than a true spinal column
- cephalopod
- marine mollusk characterized by well-developed head and eyes and sucker-bearing tentacles
- Cephalopterus ornatus
- black tropical American bird having a large overhanging crest and long feathered wattle
- Cepphus columba
- northern Pacific guillemot
- Cepphus grylle
- northern Atlantic guillemot
- Cerapteryx graminis
- European moth with white antler-like markings on the forewings; the larvae damage pastures and grasslands
- ceras
- one of the often brightly colored and branching hornlike structures on the back of the nudibranch (and other related mollusks) that serve as gills
- Cerastes cornutus
- highly venomous viper of northern Africa and southwestern Asia having a horny spine above each eye
- ceratodus
- extinct lungfish
- ceratopsian
- any of several four-footed herbivorous dinosaurs with enormous beaked skulls; of the late Cretaceous in North America and Mongolia
- ceratosaur
- primitive medium-sized theropod; swift-running bipedal carnivorous dinosaur having grasping hands with sharp claws and a short horn between the nostrils; Jurassic in North America
- Ceratotherium simum
- large light-grey African rhinoceros having two horns; endangered; sometimes placed in genus Diceros
- cercaria
- tadpole-shaped parasitic larva of a trematode worm; tail disappears in adult stage
- Cercopithecus aethiops
- white and olive green East African monkey with long white tufts of hair beside the face
- Cercopithecus aethiops pygerythrus
- South African monkey with black face and hands
- Cercopithecus aethiops sabaeus
- common savannah monkey with greenish-grey back and yellow tail
- Cercopithecus talapoin
- smallest guenon monkey; of swampy central and west African forests
- cere
- the fleshy, waxy covering at the base of the upper beak of some birds
- Certhia americana
- a common creeper in North America with a down-curved bill
- Certhia familiaris
- common European brown-and-buff tree creeper with down-curved bill
- cervid
- distinguished from Bovidae by the male's having solid deciduous antlers
- Cervus elaphus
- common deer of temperate Europe and Asia
- Cervus elaphus canadensis
- large North American deer with large much-branched antlers in the male
- Cervus unicolor
- a deer of southern Asia with antlers that have three tines
- Ceryle alcyon
- greyish-blue North American kingfisher with a chestnut band on its chest
- cestode
- ribbonlike flatworms that are parasitic in the intestines of humans and other vertebrates
- Cetonia aurata
- a common metallic green European beetle: larvae feed on plant roots and adults on leaves and flowers of e.g. roses
- Cetorhinus maximus
- large harmless plankton-eating northern shark; often swims slowly or floats at the sea surface
- chachalaca
- slender arboreal guan resembling a wild turkey; native to Central America and Mexico; highly regarded as game birds
- Chaenopsis ocellata
- found from Florida to Cuba
- chaeta
- a stiff chitinous seta or bristle especially of an annelid worm
- Chaetodipterus faber
- deep-bodied disk-shaped food fish of warmer western Atlantic coastal waters
- chaetodon
- any fish of the genus Chaetodon
- chalaza
- one of two spiral bands of tissue connecting the egg yolk to the enclosing membrane at either end of the shell
- chalcid
- any of various tiny insects whose larvae are parasites on eggs and larvae of other insects; many are beneficial in destroying injurious insects
- chalcis fly
- a variety of chalcid fly
- Chamaea fasciata
- small brown bird of California resembling a wren
- Chamaeleo chamaeleon
- a chameleon found in Africa
- Chamaeleo oweni
- a kind of chameleon
- chamaeleon
- lizard of Africa and Madagascar able to change skin color and having a projectile tongue
- chambered nautilus
- cephalopod of the Indian and Pacific oceans having a spiral shell with pale pearly partitions
- chameleon tree frog
- a form of tree toad
- char
- any of several small trout-like fish of the genus Salvelinus
- characid
- any freshwater fish of the family Characinidae
- Charadrius melodus
- small plover of eastern North America
- Charadrius morinellus
- rare plover of upland areas of Eurasia
- Charadrius vociferus
- American plover of inland waters and fields having a distinctive cry
- charger
- formerly a strong swift horse ridden into battle
- Charina bottae
- boa of grasslands and woodlands of western North America; looks and feels like rubber with tail and head of similar shape
- Charolais
- large white or cream-colored breed from France
- Charronia flavigula
- large yellow and black marten of southern China and Burma
- Chateura pelagica
- American swift that nests in e.g. unused chimneys
- chatterer
- passerine bird of New World tropics
- Chauna torquata
- largest crested screamer; native to southern Brazil and Argentina
- chela
- a grasping structure on the limb of a crustacean or other arthropods
- chelicera
- either of the first pair of fang-like appendages near the mouth of an arachnid; often modified for grasping and piercing
- Chelifer cancroides
- minute arachnid sometimes found in old papers
- Chelonia mydas
- large tropical turtle with greenish flesh used for turtle soup
- chelonian
- a reptile of the order Chelonia
- Chelydra serpentina
- large-headed turtle with powerful hooked jaws found in or near water; prone to bite
- Chen caerulescens
- North American wild goose having dark plumage in summer but white in winter
- cherrystone
- a half-grown quahog
- Chesapeake Bay retriever
- American breed having a short thick oily coat ranging from brown to light tan
- chestnut
- a dark golden-brown or reddish-brown horse
- chestnut
- a small horny callus on the inner surface of a horse's leg
- Cheviot
- hardy hornless sheep of the Cheviot Hills noted for its short thick wool
- chevrotain
- very small hornless deer-like ruminant of tropical Asia and west Africa
- Chiacoan peccary
- a recently discovered large wild pig of Paraguay
- chickadee
- any of various small grey-and-black songbirds of North America
- chicken hawk
- nontechnical term for any hawks said to prey on poultry
- chicken snake
- large North American snake
- chigger
- larval mite that sucks the blood of vertebrates including human beings causing intense irritation
- Chihuahua
- an old breed of tiny short-haired dog with protruding eyes from Mexico held to antedate Aztec civilization
- Chihuahuan spotted whiptail
- having longitudinal stripes overlaid with light spots; upland lizard of United States southwest and Mexico
- Chilomeniscus cinctus
- a sand snake of southwestern United States; lives in fine to coarse sand or loamy soil in which it `swims'; banding resembles that of coral snakes
- chimaera
- a deep-sea fish with a tapering body, smooth skin, and long threadlike tail
- Chimaera monstrosa
- large European chimaera
- Chinchilla laniger
- small rodent with soft pearly grey fur; native to the Andes but bred in captivity for fur
- chine
- backbone of an animal
- Chinese paddlefish
- fish of larger rivers of China similar to the Mississippi paddlefish
- chipmunk
- a burrowing ground squirrel of western America and Asia; has cheek pouches and a light and dark stripe running down the body
- chiton
- primitive elongated bilaterally symmetrical marine mollusk having a mantle covered with eight calcareous plates
- Chlamydera nuchalis
- large bowerbird of northern Australia
- chlamydia
- coccoid rickettsia infesting birds and mammals; cause infections of eyes and lungs and genitourinary tract
- Chlamydia psittaci
- bacteria responsible for the sexually transmitted disease chlamydia
- Chlamydia trachomatis
- bacteria responsible for the sexually transmitted diseases chlamydia and lymphogranuloma venereum
- Chlamydosaurus kingi
- large arboreal insectivorous Australian lizard with a ruff of skin around the neck
- Chlamyphorus truncatus
- very small Argentine armadillo with pale silky hair and pink plates on head and neck
- chlorella
- any alga of the genus Chlorella
- chlorofucin
- the chlorophyll present in brown algae, diatoms, and flagellates
- Chlorophoneus nigrifrons
- a kind of bush shrike
- chlorophyl
- any of a group of green pigments found in photosynthetic organisms; there are four naturally occurring forms
- chlorophyll a
- a blue-black plant pigment having a blue-green alcohol solution; found in all higher plants
- chlorophyll b
- a dark-green plant pigment having a brilliant green alcohol solution; generally characteristic of higher plants
- chlorophyll d
- the chlorophyll found (together with chlorophyll a) in red algae
- chlorophyte
- algae that are clear green in color; often growing on wet ricks or damp wood or the surface of stagnant water
- Chlorura chlorura
- towhee of the Rocky Mountains
- choanocyte
- any of the flagellated cells in sponges having a collar of cytoplasm around the flagellum; they maintain a flow of water through the body
- Choeronycteris mexicana
- small-eared Mexican bat with a long slender nose
- Choloepus didactylus
- relatively small fast-moving sloth with two long claws on each front foot
- Choloepus hoffmanni
- a sloth of Central America that has two long claws on each forefoot and three long claws on each hindfoot
- Chondrus crispus
- dark purple edible seaweed of the Atlantic coasts of Europe and North America
- chordamesoderm
- the area of mesoderm that forms the notochord
- chordate
- any animal of the phylum Chordata having a notochord or spinal column
- chordate family
- any family in the phylum Chordata
- chordate genus
- any genus in the phylum Chordata
- chorioallantoic membrane
- the very vascular fetal membrane composed of the fused chorion and adjacent wall of the allantois
- chorion
- the outermost membranous sac enclosing the embryo in higher vertebrates (reptiles, birds and mammals)
- chorionic villus
- one of the tiny villi that stick out of the fetal chorion and combine with the mother's uterine tissue to form the placenta
- Choriotis australis
- popular Australian game bird
- Chorizagrotis auxiliaris
- larvae (of a noctuid moth) that travel in large groups and destroy grains and alfalfa in the midwestern states
- chorus frog
- any of several small North American frogs having a loud call
- chough
- a European corvine bird of small or medium size with red legs and glossy black plumage
- chow
- breed of medium-sized dogs with a thick coat and fluffy curled tails and distinctive blue-black tongues; believed to have originated in northern China
- Chronoperates paradoxus
- shrew-sized protomammal from the Alberta region of Canada; from about 55 million years ago (much more recent than other mammal-like reptiles)
- chrysalis
- pupa of a moth or butterfly enclosed in a cocoon
- Chrysaora quinquecirrha
- a type of jellyfish
- Chrysemys picta
- freshwater turtles having bright yellow and red markings; common in the eastern United States
- Chrysolophus pictus
- brightly colored crested pheasant of mountains of western and central Asia
- chrysomelid
- brightly colored beetle that feeds on plant leaves; larvae infest roots and stems
- Chrysophrys auratus
- Australian food fish having a pinkish body with blue spots
- Chrysophrys australis
- important dark-colored edible food and game fish of Australia
- chrysopid
- pale green unpleasant-smelling lacewing fly having carnivorous larvae
- Chunga burmeisteri
- Argentinian Cariama
- church mouse
- a fictional mouse created by Lewis Carroll
- cicada
- stout-bodied insect with large membranous wings; male has drum-like organs for producing a high-pitched drone
- cichlid
- freshwater fishes of tropical America and Africa and Asia similar to American sunfishes; some are food fishes; many small ones are popular in aquariums
- Ciconia ciconia
- the common stork of Europe; white with black wing feathers and a red bill
- Ciconia nigra
- Old World stork that is glossy black above and white below
- ciliate
- a protozoan with a microscopic appendage extending from the surface of the cell
- cilium
- a hairlike projection from the surface of a cell; provides locomotion in free-swimming unicellular organisms
- Cimex lectularius
- bug of temperate regions that infests especially beds and feeds on human blood
- cinnamon bear
- reddish-brown color phase of the American black bear
- Circus Aeruginosus
- Old World harrier frequenting marshy regions
- Circus cyaneus
- common harrier of North America and Europe; nests in marshes and open land
- cirrus
- a slender flexible animal appendage as on barnacles or crinoids or many insects; often tactile
- Cistothorus palustris
- American wren that inhabits tall reed beds
- Cistothorus platensis
- small American wren inhabiting wet sedgy meadows
- Citation
- thoroughbred that won the triple crown in 1948
- Citellus citellus
- rather large central Eurasian ground squirrel
- Citellus lateralis
- common black-striped reddish-brown ground squirrel of western North America; resembles a large chipmunk
- Citellus leucurus
- small ground squirrel of western United States
- Citellus variegatus
- large grey ground squirrel of rocky areas of the southwestern United States
- Citharichthys cornutus
- a whiff found in waters from the Bahamas and northern Gulf of Mexico to Brazil
- civet
- cat-like mammal typically secreting musk used in perfumes
- Cladorhyncus leucocephalum
- web-footed Australian stilt with reddish-brown pectoral markings
- clam
- burrowing marine mollusk living on sand or mud; the shell closes with viselike firmness
- clamshell
- the shell of a clam
- Clangula hyemalis
- a common long-tailed sea duck of the northern parts of the United States
- class Actinozoa
- a large class of sedentary marine coelenterates that includes sea anemones and corals; the medusoid phase is entirely suppressed
- class Amphibia
- the class of vertebrates that live on land but breed in water; frogs; toads; newts; salamanders; caecilians
- class Aphasmidia
- one of two subgroups of Nematoda used in some classification systems
- class Arachnida
- a large class of arthropods including spiders and ticks and scorpions and daddy longlegs; have four pairs of walking legs and no wings
- class Archiannelida
- a class of Annelida
- class Ascidiaceae
- sometimes classified as an order: sea squirts
- class Asteroidea
- sea stars
- class Aves
- (ornithology) the class of birds
- class Bacillariophyceae
- marine and freshwater eukaryotic algae: diatoms
- class Cephalopoda
- octopuses; squids; cuttlefish; pearly nautilus
- class Cestoda
- tapeworms
- class Channidae
- snakeheads
- class Charophyceae
- in some classifications: contains only the order Charales
- class Chilopoda
- arthropods having the trunk composed of numerous somites each bearing one pair of legs: centipedes
- class Chlorophyceae
- algae distinguished chiefly by having flagella and a clear green color, their chlorophyll being masked little if at all by other pigments
- class Chondrichthyes
- cartilaginous fishes
- class Chrysophyceae
- all the yellow-green algae having flagella of unequal length
- class Ciliophora
- class of protozoa having cilia or hairlike appendages on part or all of the surface during some part of the life cycle
- class Crinoidea
- sea lilies
- class Crustacea
- class of mandibulate arthropods including: lobsters; crabs; shrimps; woodlice; barnacles; decapods; water fleas
- class Cryptophyceae
- motile usually brownish-green protozoa-like algae
- class Cyanobacteria
- photosynthetic bacteria found in fresh and salt water, having chlorophyll a and phycobilins; once thought to be algae: blue-green algae
- class Cyclosporeae
- in more recent classifications superseded by the order Fucales
- class Echinoidea
- sea urchins and sand dollars
- class Euglenophyceae
- coextensive with the division Euglenophyta
- class Gasteropoda
- snails and slugs and their relatives
- class Hexapoda
- insects; about five-sixths of all known animal species
- class Hirudinea
- hermaphroditic aquatic or terrestrial or parasitic annelids
- class Holothuroidea
- class of echinoderms including the sea cucumbers
- class Hyalospongiae
- sponges with siliceous spicules that have six rays; choanocytes are restricted to finger-shaped chambers
- class Hydrozoa
- coelenterates typically having alternation of generations; hydroid phase is usually colonial giving rise to the medusoid phase by budding: hydras and jellyfishes
- class Lamellibranchia
- oysters; clams; scallops; mussels
- class Larvacea
- small free-swimming tunicates; sometimes classified as an order
- class Mammalia
- warm-blooded vertebrates characterized by mammary glands in the female
- class Mastigophora
- protozoa having flagella
- class Merostomata
- used in some classifications; includes the orders Xiphosura and Eurypterida
- class Myriapoda
- arthropods having the body composed of numerous double somites each with two pairs of legs: millipedes
- class Nuda
- ctenophores lacking tentacles; comprises one genus: beroe
- class Oligochaeta
- earthworms
- class Onychophora
- enigmatic small elongated wormlike terrestrial invertebrates of damp dark habitats in warm regions; distinct from the phylum Annelida; resemble slugs with legs and are sometimes described as the missing link between arthropods and annelids
- class Ophiuroidea
- brittle stars and basket stars
- class Osteichthyes
- a class of fish having a skeleton composed of bone in addition to cartilage
- class Pauropoda
- an obscure class of minute arthropods with branched antennae and 8 to 10 pairs of legs
- class Phaeophyceae
- brown algae; mostly marine and littoral eukaryotic algae
- class Phasmidia
- one of two subgroups of Nematoda used in some classification systems
- class Placodermi
- extinct group of bony-plated fishes with primitive jaws
- class Polychaeta
- marine annelid worms
- class Polyplacophora
- small class of marine mollusks comprising the chitons; sometimes considered an order of the subclass Amphineura
- class Reptilia
- class of cold-blooded air-breathing vertebrates with completely ossified skeleton and a body usually covered with scales or horny plates; once the dominant land animals
- class Rhodophyceae
- coextensive with the Rhodophyta: red algae
- class Sarcodina
- characterized by the formation of pseudopods for locomotion and taking food: Actinopoda; Rhizopoda
- class Scaphopoda
- small class of bilaterally symmetrical marine forms comprising the tooth shells
- class Schizomycetes
- a former classification
- class Scyphozoa
- coelenterates in which the polyp stage is absent or at least inconspicuous: jellyfishes
- class Sporozoa
- strictly parasitic protozoans that are usually immobile; includes plasmodia and coccidia and piroplasms and malaria parasites
- class Symphyla
- small class of minute arthropods; unimportant except for the garden centipede
- class Tardigrada
- in some classifications considered a separate phylum: microscopic arachnid-like invertebrates living in water or damp moss having 4 pairs of legs and instead of a mouth a pair of stylets or needlelike piercing organs connected with the pharynx
- class Tentaculata
- ctenophores have retractile tentacles
- class Thaliacea
- small class of free-swimming tunicates; sometimes classified as an order
- class Trematoda
- parasitic flatworms (including flukes)
- class Turbellaria
- free-living flatworms
- class Ulvophyceae
- alternative name for the class Chlorophyceae in some classifications
- class Xanthophyceae
- yellow-green algae
- claw
- sharp curved horny process on the toe of a bird or some mammals or reptiles
- claw
- a bird's foot
- cleg
- large swift fly the female of which sucks blood of various animals
- clerid
- predacious on other insects; usually brightly colored or metallic
- click beetle
- able to right itself when on its back by flipping into the air with a clicking sound
- climbing salamander
- any of several North American salamanders adapted for climbing with well-developed limbs and long somewhat squared-off toes
- clingfish
- very small (to 3 inches) flattened marine fish with a sucking disc on the abdomen for clinging to rocks etc.
- clinid
- mostly small blennioid fishes of coral reefs and seagrass beds
- clostridia
- spindle-shaped bacterial cell especially one swollen at the center by an endospore
- Clostridium botulinum
- anaerobic bacterium producing botulin the toxin that causes botulism
- clostridium perfringens
- anaerobic Gram-positive rod bacterium that produces epsilon toxin; can be used as a bioweapon
- clothes moth
- any of several small yellowish or buff-colored moths whose larvae eat organic matter e.g. woolens
- cloven foot
- a hoof divided into two parts at its distal extremity (as of ruminants or swine)
- clumber
- a thickset spaniel with longish silky hair
- Clupea harangus
- commercially important food fish of northern waters of both Atlantic and Pacific
- Clupea harengus harengus
- important food fish; found in enormous shoals in the northern Atlantic
- Clupea harengus pallasii
- important food fish of the northern Pacific
- Clupea sprattus
- small herring processed like a sardine
- clupeid
- any of numerous soft-finned schooling food fishes of shallow waters of northern seas
- Clydesdale
- heavy feathered-legged breed of draft horse originally from Scotland
- Clydesdale terrier
- selectively bred small Skye terrier with erect ears and a long silky coat
- clypeus
- a shield-like plate on the front of an insect's head
- CMV
- any of a group of herpes viruses that enlarge epithelial cells and can cause birth defects; can affect humans with impaired immunological systems
- Cnemidophorus sexlineatus
- very swift lizard of eastern and central United States
- Cnemidophorus tesselatus
- markings are darker and more marked than in western whiptail; from southeastern Colorado to eastern Chihuahua
- Cnemidophorus tigris
- active lizard having a network of dusky dark markings; of semiarid areas from Oregon and Idaho to Baja California
- Cnemidophorus velox
- having distinct longitudinal stripes: of Colorado Plateau from Arizona to western Colorado
- cnidarian
- radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms
- coach horse
- strong draft horse for drawing coaches
- coastal diving bird
- gull family; skimmer family; jaeger family; auk family
- coat
- growth of hair or wool or fur covering the body of an animal
- cob
- adult male swan
- cob
- stocky short-legged harness horse
- cobra
- venomous Asiatic and African elapid snakes that can expand the skin of the neck into a hood
- cocci
- any spherical or nearly spherical bacteria
- coccid insect
- scale insects and mealybugs
- coccidium
- parasitic on the digestive epithelium of vertebrates and higher invertebrates
- coccobacillus
- a bacterial cell intermediate in morphology between a coccus and a bacillus; a very short bacillus
- Coccothraustes coccothraustes
- a common large finch of Eurasia
- Coccus hesperidum
- pest on citrus trees
- Coccyzus erythropthalmus
- North American cuckoo; builds a nest and rears its own young
- cochin
- Asian breed of large fowl with dense plumage and feathered legs
- Cochlearius cochlearius
- tropical American heron related to night herons
- cock
- adult male bird
- cock
- adult male chicken
- cockatoo
- white or light-colored crested parrot of the Australian region; often kept as cage birds
- cockerel
- a young domestic cock; not older than one year
- cockle
- common edible, burrowing European bivalve mollusk that has a strong, rounded shell with radiating ribs
- cockroach
- any of numerous chiefly nocturnal insects; some are domestic pests
- cockscomb
- the fleshy red crest on the head of the domestic fowl and other gallinaceous birds
- cocoon
- silky envelope spun by the larvae of many insects to protect pupas and by spiders to protect eggs
- cod
- major food fish of Arctic and cold-temperate waters
- codling
- young codfish
- coelenterate family
- a family of coelenterates
- coelenterate genus
- a genus of coelenterates
- coelenteron
- the saclike body cavity of a coelenterate
- coelophysis
- one of the oldest known dinosaurs; late Triassic; cannibalistic
- Colaptes auratus
- large flicker of eastern North America with a red neck and yellow undersurface to wings and tail
- Colaptes caper collaris
- western United States bird with red undersurface to wings and tail
- Colaptes chrysoides
- southwestern United States bird like the yellow-shafted flicker but lacking the red neck
- Colinus virginianus
- a favorite game bird of eastern and central United States
- coliphage
- a bacteriophage that infects the bacterium Escherichia coli
- collared lizard
- any of several robust long-tailed lizards with collars of two dark bands; of central and western United States and northern Mexico
- collembolan
- any of numerous minute wingless primitive insects possessing a special abdominal appendage that allows the characteristic nearly perpetual springing pattern; found in soil rich in organic debris or on the surface of snow or water
- collie
- a silky-coated sheepdog with a long ruff and long narrow head developed in Scotland
- Collocalia inexpectata
- swift of eastern Asia; produces the edible bird's nest
- Colobus guereza
- a colobus monkey with a reddish brown coat and white silky fringes down both sides of the body
- colobus
- arboreal monkey of western and central Africa with long silky fur and reduced thumbs
- colt
- a young male horse under the age of four
- Coluber constrictor
- blackish racer of the eastern United States that grows to six feet
- Coluber constrictor flaviventris
- bluish-green blacksnake found from Ohio to Texas
- Coluber hippocrepis
- slender fast-moving Eurasian snake
- colubrid
- mostly harmless temperate-to-tropical terrestrial or arboreal or aquatic snakes
- colugo
- arboreal nocturnal mammal of southeast Asia and the Philippines resembling a lemur and having a fold of skin on each side from neck to tail that is used for long gliding leaps
- Columba fasciata
- wild pigeon of western North America; often mistaken for the now extinct passenger pigeon
- Columba livia
- pale grey Eurasian pigeon having black-striped wings from which most domestic species are descended
- Columba palumbus
- Eurasian pigeon with white patches on wings and neck
- columbiform bird
- a cosmopolitan order of land birds having small heads and short legs with four unwebbed toes
- comatulid
- free-swimming stalkless crinoid with ten feathery arms; found on muddy sea bottoms
- comb
- ciliated comb-like swimming plate of a ctenophore
- comb jelly
- biradially symmetrical hermaphroditic solitary marine animals resembling jellyfishes having for locomotion eight rows of cilia arranged like teeth in a comb
- comb-footed spider
- spider having a comb-like row of bristles on each hind foot
- comb-plate
- a locomotor organ consisting of a row of strong cilia whose bases are fused
- commensal
- either of two different animal or plant species living in close association but not interdependent
- common American shad
- shad of Atlantic coast of North America; naturalized to Pacific coast
- common eel
- eels that live in fresh water as adults but return to sea to spawn; found in Europe and America; marketed both fresh and smoked
- common European earwig
- sometimes destructive to cultivated bulbs
- common European jay
- fawn-colored jay with black-and-white crest and blue-and-black wings
- compsognathus
- very small bipedal carnivorous dinosaur of the late Jurassic in Bavaria
- conceptus
- an animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval life
- conch
- any of various edible tropical marine gastropods of the genus Strombus having a brightly-colored spiral shell with large outer lip
- condor
- the largest flying birds in the western hemisphere
- Condylura cristata
- amphibious mole of eastern North America having pink fleshy tentacles around the nose
- Conepatus leuconotus
- large naked-muzzled skunk with white back and tail; of southwestern North America and Mexico
- coney
- any of several small ungulate mammals of Africa and Asia with rodent-like incisors and feet with hooflike toes
- coney
- small short-eared burrowing mammal of rocky uplands of Asia and western North America
- coney
- any of various burrowing animals of the family Leporidae having long ears and short tails; some domesticated and raised for pets or food
- conferva
- any of various algae of the genus Tribonema; algae with branching filaments that form scum in still or stagnant fresh water
- confervoid algae
- algae resembling confervae especially in having branching filaments
- congenator
- an animal or plant that bears a relationship to another (as related by common descent or by membership in the same genus)
- conger
- large dark-colored scaleless marine eel found in temperate and tropical coastal waters; some used for food
- conodont
- small (2 inches long) extinct eellike fish with a finned tail and a notochord and having cone-shaped teeth containing cellular bone; late Cambrian to late Triassic; possible predecessor of the cyclostomes
- conodont
- the tiny fossil cone-shaped tooth of a primitive vertebrate of order Conodonta
- conspecific
- an organism belonging to the same species as another organism
- constrictor
- any of various large nonvenomous snakes that kill their prey by crushing it in its coils
- Constrictor constrictor
- very large boa of tropical America and West Indies
- Contopus sordidulus
- small flycatcher of western North America
- Contopus virens
- small olive-colored woodland flycatchers of eastern North America
- contour feather
- feathers covering the body of an adult bird and determining its shape
- Conuropsis carolinensis
- extinct parakeet whose range extended far into the United States
- coondog
- any dog trained to hunt raccoons
- coonhound
- any of several breeds of hound developed for hunting raccoons
- coot
- slate-black slow-flying birds somewhat resembling ducks
- copepod
- minute marine or freshwater crustaceans usually having six pairs of limbs on the thorax; some abundant in plankton and others parasitic on fish
- copper
- any of various small butterflies of the family Lycaenidae having coppery wings
- Coracias garrulus
- common European blue-and-green roller with a reddish-brown back
- coraciiform bird
- chiefly short-legged arboreal nonpasserine birds that nest in holes
- Coragyps atratus
- American vulture smaller than the turkey buzzard
- coral
- marine colonial polyp characterized by a calcareous skeleton; masses in a variety of shapes often forming reefs
- Coregonus artedi
- important food fish of cold deep lakes of North America
- Coregonus clupeaformis
- found in the Great Lakes and north to Alaska
- coreid
- a true bug
- cornetfish
- slender tropical fish with a long tubular snout and bony plates instead of scales
- Cornish fowl
- English breed of compact domestic fowl; raised primarily to crossbreed to produce roasters
- coronet
- margin between the skin of the pastern and the horn of the hoof
- corvine bird
- birds of the crow family
- Corvus brachyrhyncos
- common crow of North America
- Corvus corax
- large black bird with a straight bill and long wedge-shaped tail
- Corvus frugilegus
- common gregarious Old World bird about the size and color of the American crow
- Corvus monedula
- common black-and-grey Eurasian bird noted for thievery
- Corydalus cornutus
- large soft-bodied insect having long slender mandibles in the male; aquatic larvae often used as bait
- corynebacterium
- any species of the genus Corynebacterium
- Corynebacterium diphtheriae
- a species of bacterium that causes diphtheria
- Coryphaena equisetis
- a kind of dolphinfish
- Coryphaena hippurus
- the more common dolphinfish valued as food; about six feet long
- corythosaur
- duck-billed dinosaur with nasal passages that expand into a crest like a hollow helmet
- coscoroba
- large white South American bird intermediate in some respects between ducks and swans
- cosmid
- (genetics) a large vector that is made from a bacteriophage and used to clone genes or gene fragments
- Cosmocampus profundus
- a fish 8 inches long; found from eastern Florida to western Caribbean
- Costia necatrix
- a flagellate that is the cause of the frequently fatal fish disease costiasis
- Cotswold
- sheep with long wool originating in the Cotswold Hills
- cotton stainer
- a true bug: bug that damages and stains the lint of developing cotton
- cotton strain
- feeds primarily on cotton
- cottontail
- common small rabbit of North America having greyish or brownish fur and a tail with a white underside; a host for Ixodes pacificus and Ixodes scapularis (Lyme disease ticks)
- Coturnix coturnix
- the typical Old World quail
- coucal
- Old World ground-living cuckoo having a long dagger-like hind claw
- Count Fleet
- thoroughbred that won the triple crown in 1943
- courser
- swift-footed terrestrial plover-like bird of southern Asia and Africa; related to the pratincoles
- courser
- a dog trained for coursing
- cow
- mature female of mammals of which the male is called `bull'
- cow pony
- a light saddle horse trained for herding cattle
- cow
- female of domestic cattle:
- cowbird
- North American blackbird that follows cattle and lays eggs in other birds' nests
- cowrie
- any of numerous tropical marine gastropods of the genus Cypraea having highly polished usually brightly marked shells
- Coxsackie virus
- enterovirus causing a disease resembling poliomyelitis but without paralysis
- coydog
- offspring of a coyote and a dog
- crab
- decapod having eyes on short stalks and a broad flattened carapace with a small abdomen folded under the thorax and pincers
- crab-eating opossum
- South American opossum
- crabeater seal
- silvery grey Antarctic seal subsisting on crustaceans
- crake
- any of several short-billed Old World rails
- crampfish
- any sluggish bottom-dwelling ray of the order Torpediniformes having a rounded body and electric organs on each side of the head capable of emitting strong electric discharges
- crane
- large long-necked wading bird of marshes and plains in many parts of the world
- crane fly
- long-legged slender flies that resemble large mosquitoes but do not bite
- craniate
- animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium
- crappie
- small sunfishes of central United States rivers
- craw
- a pouch in many birds and some lower animals that resembles a stomach for storage and preliminary maceration of food
- crawdad
- small freshwater decapod crustacean that resembles a lobster
- crawfish
- large edible marine crustacean having a spiny carapace but lacking the large pincers of true lobsters
- creeper
- any of various small insectivorous birds of the northern hemisphere that climb up a tree trunk supporting themselves on stiff tail feathers and their feet
- creepy-crawly
- an animal that creeps or crawls (such as worms or spiders or insects)
- crest
- a showy growth of e.g. feathers or skin on the head of a bird or other animal
- crested penguin
- small penguin of the Falkland Islands and New Zealand
- crested screamer
- distinguished from the horned screamer by a feathery crest on the back of the head
- crested swift
- birds of southeast Asia and East Indies differing from true swifts in having upright crests and nesting in trees
- Crex crex
- common Eurasian rail that frequents grain fields
- Cricetus cricetus
- a variety of hamster common to Europe and Asia
- cricket
- leaping insect; male makes chirping noises by rubbing the forewings together
- cricket frog
- either of two frogs with a clicking call
- crinoid
- primitive echinoderms having five or more feathery arms radiating from a central disk
- critter
- a regional term for `creature' (especially for domestic animals)
- Cro-magnon
- extinct human of Upper Paleolithic in Europe
- croaker
- any of several fishes that make a croaking noise
- Crocethia alba
- small sandpiper that breeds in the Arctic and migrates southward along sandy coasts in most of world
- crocodile
- large voracious aquatic reptile having a long snout with massive jaws and sharp teeth and a body covered with bony plates; of sluggish tropical waters
- crocodilian
- extant archosaurian reptile
- Crocodylus niloticus
- a dangerous crocodile widely distributed in Africa
- Crocodylus porosus
- estuarine crocodile of eastern Asia and Pacific islands
- Crocuta crocuta
- African hyena noted for its distinctive howl
- cross
- (genetics) an organism that is the offspring of genetically dissimilar parents or stock; especially offspring produced by breeding plants or animals of different varieties or breeds or species
- crossopterygian
- any fish of the order Crossopterygii; most known only in fossil form
- Crotalus adamanteus
- large deadly rattlesnake with diamond-shaped markings
- Crotalus cerastes
- small pale-colored desert rattlesnake of southwestern United States; body moves in an s-shaped curve
- Crotalus horridus atricaudatus
- southern variety
- Crotalus horridus horridus
- widely distributed in rugged ground of eastern United States
- Crotalus lepidus
- mountain rock dweller of Mexico and most southern parts of United States southwest
- Crotalus mitchellii
- markings vary but usually harmonize with background; of southwestern Arizona and Baja California
- Crotalus scutulatus
- extremely dangerous; most common in areas of scattered scrubby growth; from Mojave Desert to western Texas and into Mexico
- Crotalus tigris
- having irregularly cross-banded back; of arid foothills and canyons of southern Arizona and Mexico
- croup
- the part of an animal that corresponds to the human buttocks
- crow
- black birds having a raucous call
- crow blackbird
- long-tailed American blackbird having iridescent black plumage
- crowbait
- an emaciated horse likely soon to become carrion and so attractive to crows
- crucifix fish
- sea catfish of the Caribbean area
- crustacean
- any mainly aquatic arthropod usually having a segmented body and chitinous exoskeleton
- Cryptacanthodes maculatus
- eellike Atlantic bottom fish with large almost vertical mouth
- Cryptobranchus alleganiensis
- large salamander of North American rivers and streams
- cryptomonad
- common in fresh and salt water appearing along the shore as algal blooms
- Cryptoprocta ferox
- largest carnivore of Madagascar; intermediate in some respects between cats and civets
- Cryptotermes brevis
- extremely destructive dry-wood termite of warm regions
- Cryptotis parva
- small brown shrew of grassy regions of eastern United States
- ctenidium
- comb-like respiratory structure serving as the gill of certain mollusks
- Ctenocephalides canis
- flea that attacks dogs and cats
- Ctenocephalides felis
- flea that breeds chiefly on cats and dogs and rats
- ctenophore family
- a family of ctenophores
- ctenophore genus
- a genus of ctenophores
- cub
- the young of certain carnivorous mammals such as the bear or wolf or lion
- cuckoo
- any of numerous European and North American birds having pointed wings and a long tail
- cuckoo-bumblebee
- a bee that is parasitic in the nests of bumblebees
- cuculiform bird
- birds having zygodactyl feet (except for the touracos)
- Culex pipiens
- common house mosquito
- Culex quinquefasciatus
- widespread tropical mosquito that transmits filarial worms
- Cuniculus paca
- large burrowing rodent of South America and Central America; highly esteemed as food
- Cuon alpinus
- fierce wild dog of the forests of central and southeast Asia that hunts in packs
- cupule
- a sucker on the feet of certain flies
- cur
- an inferior dog or one of mixed breed
- curassow
- large crested arboreal game bird of warm parts of the Americas having long legs and tails; highly esteemed as game and food
- curlew
- large migratory shorebirds of the sandpiper family; closely related to woodcocks but having a down-curved bill
- curly-coated retriever
- an English breed having a tightly curled black or liver-colored coat; retrieves game from land or water
- Cursorius cursor
- courser of desert and semidesert regions of the Old World
- cuscus
- woolly-haired monkey-like arboreal marsupial of New Guinea and northern Australia
- cusk-eel
- elongate compressed somewhat eel-shaped fishes
- cuticula
- the outer body wall of an insect
- cutlassfish
- long-bodied marine fishes having a long whiplike scaleless body and sharp teeth; closely related to snake mackerel
- cuttle
- ten-armed oval-bodied cephalopod with narrow fins as long as the body and a large calcareous internal shell
- cutworm
- North American moth whose larvae feed on young plant stems cutting them off at the ground
- Cyanocitta cristata
- common jay of eastern North America; bright blue with grey breast
- Cyclopes didactylus
- squirrel-sized South American toothless anteater with long silky golden fur
- cyclops
- minute free-swimming freshwater copepod having a large median eye and pear-shaped body and long antennae used in swimming; important in some food chains and as intermediate hosts of parasitic worms that affect man e.g. Guinea worms
- Cyclopterus lumpus
- clumsy soft thick-bodied northern Atlantic fish with pelvic fins fused into a sucker; edible roe used for caviar
- cyclostome
- primitive aquatic vertebrate
- cygnet
- a young swan
- Cygnus atratus
- large Australian swan having black plumage and a red bill
- Cygnus buccinator
- large pure white wild swan of western North America having a sonorous cry
- Cygnus columbianus
- swan that nests in tundra regions of the New and Old Worlds
- Cygnus columbianus bewickii
- Eurasian subspecies of tundra swan; smaller than the whooper
- Cygnus columbianus columbianus
- North American subspecies of tundra swan having a soft whistling note
- Cygnus cygnus
- common Old World swan noted for its whooping call
- Cygnus olor
- soundless Eurasian swan; commonly domesticated
- cynipid gall wasp
- small solitary wasp that produces galls on oaks and other plants
- Cynocephalus variegatus
- a variety of flying lemur
- cynodont
- small carnivorous reptiles
- Cynomys gunnisoni
- tail is white tipped
- Cynomys ludovicianus
- tail is black tipped
- Cynopterus sphinx
- a variety of fruit eating bat
- Cynoscion nebulosus
- weakfish of southern Atlantic and Gulf Coasts of United States
- Cynoscion regalis
- food and game fish of North American coastal waters with a mouth from which hooks easily tear out
- Cypraea moneta
- cowrie whose shell is used for money in parts of the southern Pacific and in parts of Africa
- Cypraea tigris
- cowrie whose shell is used for ornament
- cyprinid
- soft-finned mainly freshwater fishes typically having toothless jaws and cycloid scales
- cypriniform fish
- a soft-finned fish of the order Cypriniformes
- cyprinodont
- any member of the family Cyprinodontidae
- Cyprinus carpio
- large Old World freshwater bottom-feeding fish introduced into Europe from Asia; inhabits ponds and sluggish streams and often raised for food; introduced into United States where it has become a pest
- Cystophora cristata
- medium-sized blackish-grey seal with large inflatable sac on the head; of Arctic and northern Atlantic waters
- cytostome
- mouth of a protozoan
- dabbler
- any of numerous shallow-water ducks that feed by upending and dabbling
- Dacelo gigas
- Australian kingfisher having a loud cackling cry
- Dactylopius coccus
- Mexican red scale insect that feeds on cacti; the source of a red dye
- dairy cattle
- cattle that are reared for their milk
- dam
- female parent of an animal especially domestic livestock
- Dama dama
- small Eurasian deer
- Damaliscus lunatus
- a large South African antelope; considered the swiftest hoofed mammal
- Damaraland mole rat
- colonial mole rat of western Africa; similar to naked mole rat
- damselfish
- small brilliantly colored tropical marine fishes of coral reefs
- damselfly
- slender non-stinging insect similar to but smaller than the dragonfly but having wings folded when at rest
- danaid
- large tropical butterfly with degenerate forelegs and an unpleasant taste
- Danaus plexippus
- large migratory American butterfly having deep orange wings with black and white markings; the larvae feed on milkweed
- Dandie Dinmont terrier
- a breed of small terrier with long wiry coat and drooping ears
- daphnia
- minute freshwater crustacean having a round body enclosed in a transparent shell; moves about like a flea by means of hairy branched antennae
- dark horse
- a racehorse about which little is known
- darkling beetle
- sluggish hard-bodied black terrestrial weevil whose larvae feed on e.g. decaying plant material or grain
- darning needle
- slender-bodied non-stinging insect having iridescent wings that are outspread at rest; adults and nymphs feed on mosquitoes etc.
- darter
- a person or other animal that moves abruptly and rapidly
- Dasyatis centroura
- one of the largest stingrays; found from Cape Cod to Cape Hatteras
- Dasyprocta aguti
- agile long-legged rabbit-sized rodent of Central America and South America and the West Indies; valued as food
- Dasypus novemcinctus
- having nine hinged bands of bony plates; ranges from Texas to Paraguay
- dasyure
- any of several more or less arboreal marsupials somewhat resembling martens
- dasyurid
- small carnivorous nocturnal marsupials of Australia and Tasmania
- Dasyurus quoll
- a variety of dasyure
- Dasyurus viverrinus
- carnivorous arboreal cat-like marsupials of Australia and Tasmania
- Daubentonia madagascariensis
- nocturnal lemur with long bony fingers and rodent-like incisor teeth closely related to the lemurs
- dawn horse
- earliest horse; extinct primitive dog-sized four-toed Eocene animal
- dayfly
- slender insect with delicate membranous wings having an aquatic larval stage and terrestrial adult stage usually lasting less than two days
- decapod
- cephalopods having eight short tentacles plus two long ones
- decapod
- crustaceans characteristically having five pairs of locomotor appendages each joined to a segment of the thorax
- Decapterus macarellus
- small silvery fish; Nova Scotia to Brazil
- Decapterus punctatus
- small fusiform fish of western Atlantic
- definitive host
- the host in which the sexual reproduction of a parasite takes place
- defoliator
- an insect that strips the leaves from plants
- deinocheirus
- lightly built medium-sized theropod with long limbs and neck
- deinonychus
- swift agile wolf-sized bipedal dinosaur having a large curved claw on each hind foot; of the Cretaceous
- Delichon urbica
- common small European martin that builds nests under the eaves of houses
- Delphinapterus leucas
- small northern whale that is white when adult
- Delphinus delphis
- black-and-white dolphin that leaps high out of the water
- Dendroaspis augusticeps
- a highly venomous southern African mamba dreaded because of its quickness and readiness to bite
- Dendroctonus rufipennis
- small beetle that likes to bore through the bark of spruce trees and eat the cambium which eventually kills the tree
- Dendroica auduboni
- common warbler of western North America
- Dendroica coronata
- similar to Audubon's warbler
- Dendroica petechia
- yellow-throated American wood warbler
- Dendroica striate
- North American warbler having a black-and-white head
- Dendroica tigrina
- North American wood warbler; olive green and yellow striped with black
- Denisonia superba
- venomous but sluggish reddish-brown snake of Australia
- denizen
- a plant or animal naturalized in a region
- denticle
- small pointed ridge on the exoskeleton of an arthropod
- Dermacentor variabilis
- common tick that can transmit Rocky Mountain spotted fever and tularemia
- Dermatobia hominis
- large tropical American fly; parasitic on humans and other mammals
- Dermochelys coriacea
- wide-ranging marine turtle with flexible leathery carapace; largest living turtle
- desmid
- freshwater green algae
- Desmodus rotundus
- mouse-sized bat of tropical Central America and South America having sharp incisor and canine teeth; feeds on the blood of birds and mammals
- devilfish
- extremely large pelagic tropical ray that feeds on plankton and small fishes; usually harmless but its size make it dangerous if harpooned
- devilfish
- bottom-living cephalopod having a soft oval body with eight long tentacles
- Devon
- red dual-purpose cattle of English origin
- Dialeurodes citri
- whitefly that attacks citrus trees
- Diapheromera femorata
- a variety of stick insect
- diapsid
- reptile having a pair of openings in the skull behind each eye
- diatom
- microscopic unicellular marine or freshwater colonial alga having cell walls impregnated with silica
- dibranch
- cephalopods having two gills
- dicamptodon
- salamanders found near cold streams throughout the year
- Diceros bicornis
- African rhino; in danger of extinction
- dickeybird
- small bird; adults talking to children sometimes use these words to refer to small birds
- dictyopterous insect
- cockroaches and mantids
- dicynodont
- a kind of therapsid
- Didelphis marsupialis
- omnivorous opossum of the eastern United States; noted for feigning death when in danger; esteemed as food in some areas; considered same species as the crab-eating opossum of South America
- difflugia
- a protozoan with an ovoid shell of cemented sand grains
- digger wasp
- solitary wasp that digs nests in the soil and stocks them with paralyzed insects for the larvae
- digitigrade
- an animal that walks so that only the toes touch the ground as e.g. dogs and cats and horses
- dihybrid
- a hybrid produced by parents that differ only at two gene loci that have two alleles each
- dik-dik
- any of several small antelopes of eastern Africa of the genus Madoqua; the size of a large rabbit
- dimetrodon
- carnivorous dinosaur of the Permian in North America having a crest or dorsal sail
- dinoceras
- a variety of dinocerate
- dinocerate
- an extinct ungulate
- dinoflagellate
- chiefly marine protozoa having two flagella; a chief constituent of plankton
- Dinornis giganteus
- the largest moa; about 12 feet high
- dinosaur
- any of numerous extinct terrestrial reptiles of the Mesozoic era
- Diodon holocanthus
- similar to but smaller than porcupinefish
- Diodon hystrix
- spines become erect when the body is inflated; worldwide in warm waters
- Diomedea exulans
- very large albatross; white with wide black wings
- Diomedea nigripes
- a variety of albatross with black feet
- Diphylla ecaudata
- similar in size and habits to Desmodus rotundus; of tropical America including southern California and Texas
- diplococcus
- Gram-positive bacteria usually occurring in pairs
- Diplococcus pneumoniae
- bacterium causing pneumonia in mice and humans
- diplodocus
- a huge quadrupedal herbivore with long neck and tail; of late Jurassic in western North America
- diploid
- (genetics) an organism or cell having the normal amount of DNA per cell; i.e., two sets of chromosomes or twice the haploid number
- Dipodomys phillipsii
- any of various leaping rodents of desert regions of North America and Mexico; largest members of the family Heteromyidae
- dipper
- small stocky diving bird without webbed feet; frequents fast-flowing streams and feeds along the bottom
- Dipsosaurus dorsalis
- small long-tailed lizard of arid areas of southwestern United States and northwestern Mexico
- dipteran
- insects having usually a single pair of functional wings (anterior pair) with the posterior pair reduced to small knobbed structures and mouth parts adapted for sucking or lapping or piercing
- diver
- large somewhat primitive fish-eating diving bird of the northern hemisphere having webbed feet placed far back; related to the grebes
- diving duck
- any of various ducks of especially bays and estuaries that dive for their food
- diving petrel
- any of several small diving birds of southern hemisphere seas; somewhat resemble auks
- division Archaebacteria
- in some classifications considered a kingdom
- division Chlorophyta
- large division of chiefly freshwater eukaryotic algae that possess chlorophyll a and b, store food as starch, and cellulose cell walls; classes Chlorophyceae, Ulvophyceae, and Charophyceae; obviously ancestral to land plants
- division Chrysophyta
- mostly freshwater eukaryotic algae having the chlorophyll masked by brown or yellow pigment; yellow-green and golden-brown algae and diatoms: Xanthophyceae, Chrysophyceae, Bacillariophyceae; some classification systems superseded or subsumed by Heterokontophyta
- division Cyanophyta
- prokaryotic organisms sometimes considered a class or phylum or subkingdom; coextensive with the Cyanophyceae: cyanobacteria (blue-green algae)
- division Cynodontia
- a division of the order Therapsida from the Triassic period comprising small carnivorous tetrapod reptiles often with mammal-like teeth
- division Dicynodontia
- a division of Therapsida
- division Eubacteria
- one-celled monerans having simple cells with rigid walls and (in motile types) flagella
- division Euglenophyta
- free-swimming flagellate algae
- division Heterokontophyta
- algae having chlorophyll a and usually c, and flagella of unequal lengths; terminology supersedes Chrysophyta in some classifications
- division Phaeophyta
- coextensive with class Phaeophyceae; in some classifications subsumed in the division Heterokontophyta
- division Protista
- eukaryotic one-celled living organisms distinct from multicellular plants and animals: protozoa, slime molds, and eukaryotic algae
- division Rhodophyta
- lower plants; mostly marine and littoral eukaryotic algae
- division Schizophyta
- former term for the Cyanophyta
- dobbin
- a quiet plodding workhorse
- Doberman pinscher
- medium large breed of dog of German origin with a glossy black and tan coat; used as a watchdog
- dobson
- large brown aquatic larva of the dobsonfly; used as fishing bait
- dock
- the solid bony part of the tail of an animal as distinguished from the hair
- doe
- mature female of mammals of which the male is called `buck'
- dog-day cicada
- its distinctive song is heard during July and August
- dogfish
- any of several small sharks
- dogie
- motherless calf in a range herd of cattle
- Dolichonyx oryzivorus
- migratory American songbird
- Dolichotis patagonum
- hare-like rodent of the pampas of Argentina
- doliolum
- free-swimming oceanic tunicate with a barrel-shaped transparent body
- dolphin
- any of various small toothed whales with a beaklike snout; larger than porpoises
- dolphin
- large slender food and game fish widely distributed in warm seas (especially around Hawaii)
- domestic animal
- any of various animals that have been tamed and made fit for a human environment
- domestic fowl
- a domesticated gallinaceous bird thought to be descended from the red jungle fowl
- domestic pigeon
- domesticated pigeon raised for sport or food
- Dominique
- American breed of chicken having barred grey plumage raised for meat and brown eggs
- Donald Duck
- a fictional duck created in animated film strips by Walt Disney
- dorbeetle
- Old World dung beetle that flies with a droning sound
- Dorking
- an English breed of large domestic fowl having five toes (the hind toe doubled)
- dormouse
- small furry-tailed squirrel-like Old World rodent that becomes torpid in cold weather
- dorsal fin
- unpaired median fin on the backs of fishes and some other aquatic vertebrates that help to maintain balance
- dory
- marine fishes widely distributed in mid-waters and deep slope waters
- dove
- any of numerous small pigeons
- dowitcher
- shorebird of the sandpiper family that resembles a snipe
- down
- soft fine feathers
- downy woodpecker
- small North American woodpecker with black and white plumage and a small bill
- Dracunculus medinensis
- parasitic roundworm of India and Africa that lives in the abdomen or beneath the skin of humans and other vertebrates
- draft animal
- an animal used for pulling heavy loads
- draft horse
- horse adapted for drawing heavy loads
- dragon
- any of several small tropical Asian lizards capable of gliding by spreading winglike membranes on each side of the body
- dragonet
- small often brightly colored scaleless marine bottom-dwellers; found in tropical and warm temperate waters of Europe and America
- drake
- adult male of a wild or domestic duck
- Dreissena polymorpha
- inch long mollusk imported accidentally from Europe; clogs utility inlet pipes and feeds on edible freshwater mussels
- driftfish
- small (6 inches) tropical butterfishes found worldwide
- driftfish
- larger butterfishes of the western Atlantic from the New York area to the northern Gulf of Mexico
- dromaeosaur
- a kind of maniraptor
- Dromaius novaehollandiae
- large Australian flightless bird similar to the ostrich but smaller
- drone
- stingless male bee in a colony of social bees (especially honeybees) whose sole function is to mate with the queen
- Drosophila melanogaster
- small fruit fly used by Thomas Hunt Morgan in studying basic mechanisms of inheritance
- drum
- small to medium-sized bottom-dwelling food and game fishes of shallow coastal and fresh waters that make a drumming noise
- dry-wood termite
- any of various termites that live in and feed on dry wood that is not connected with the soil
- Drymarchon corais
- large dark-blue nonvenomous snake that invades burrows; found in southern North America and Mexico
- Drymarchon corais couperi
- a variety of indigo snake
- dryopithecine
- considered a possible ancestor to both anthropoid apes and humans
- Dryopithecus Rudapithecus hungaricus
- fossil hominoids from northern central Hungary; late Miocene
- duck
- small wild or domesticated web-footed broad-billed swimming bird usually having a depressed body and short legs
- duck down
- down of the duck
- duck-billed dinosaur
- any of numerous large bipedal ornithischian dinosaurs having a horny duck-like bill and webbed feet; may have been partly aquatic
- duckling
- young duck
- dug
- an udder or breast or teat
- Dugong dugon
- sirenian tusked mammal found from eastern Africa to Australia; the flat tail is bilobate
- Dumetella carolinensis
- North American songbird whose call resembles a cat's mewing
- dun
- horse of a dull brownish grey color
- dung beetle
- any of numerous beetles that roll balls of dung on which they feed and in which they lay eggs
- Duplicidentata
- in former classifications considered a suborder of Rodentia coextensive with the order Lagomorpha: gnawing animals
- Durham
- English breed of short-horned cattle
- Dusicyon cancrivorus
- wild dog of northern South America
- dusky salamander
- common North American salamander mottled with dull brown or greyish-black
- dusky-footed wood rat
- a wood rat with dusky feet
- dwarf pocket rat
- small silky-haired pouched rodent; similar to but smaller than kangaroo rats
- Eacles imperialis
- large American moth having yellow wings with purplish or brownish markings; larvae feed on e.g. maple and pine trees
- eagle ray
- powerful free-swimming tropical ray noted for `soaring' by flapping winglike fins; usually harmless but has venomous tissue near base of the tail as in stingrays
- eaglet
- a young eagle
- eared seal
- pinniped mammal having external ear flaps and hind limbs used for locomotion on land; valued for its soft underfur
- earless lizard
- any of several slender lizards without external ear openings: of plains of western United States and Mexico
- earless seal
- any of several seals lacking external ear flaps and having a stiff hairlike coat with hind limbs reduced to swimming flippers
- earwig
- any of numerous insects of the order Dermaptera having elongate bodies and slender many-jointed antennae and a pair of large pincers at the rear of the abdomen
- Easter bunny
- a rabbit that delivers Easter eggs
- eastern kingbird
- a kingbird that breeds in North America and winters in tropical America; distinguished by a white band on the tip of the tail
- Ebola virus
- a filovirus that causes Ebola hemorrhagic fever; carried by animals; can be used as a bioweapon
- Echeneis naucrates
- remoras found attached to sharks
- Echidnophaga gallinacea
- parasitic on especially the heads of chickens
- echinococcus
- tapeworms whose larvae are parasitic in humans and domestic animals
- echinoderm
- marine invertebrates with tube feet and five-part radially symmetrical bodies
- echinoderm family
- a family of echinoderms
- echinoderm genus
- a genus of echinoderms
- Echinus esculentus
- a sea urchin that can be eaten
- echovirus
- any of a group of viruses associated with various diseases including viral meningitis and mild respiratory disorders and diarrhea in newborn infants
- ectoblast
- the outer germ layer that develops into skin and nervous tissue
- ectoparasite
- any external parasitic organism (as fleas)
- Ectopistes migratorius
- gregarious North American migratory pigeon now extinct
- ectoproct
- sessile mossy aquatic animal having the anus of the polyp outside the crown of tentacles
- ectotherm
- an animal whose body temperature varies with the temperature of its surroundings; any animal except birds and mammals
- edaphosaurus
- heavy-bodied reptile with a dorsal sail or crest; of the late Paleozoic
- edentate
- primitive terrestrial mammal with few if any teeth; of tropical Central America and South America
- Edmontonia
- heavily armored and highly spiked dinosaur with semi-upright posture
- edmontosaurus
- duck-billed dinosaur from Canada found as a fossilized mummy with skin
- eel
- voracious snakelike marine or freshwater fishes with smooth slimy usually scaleless skin and having a continuous vertical fin but no ventral fins
- eelblenny
- eellike fishes found in subarctic coastal waters
- eelpout
- marine eellike mostly bottom-dwelling fishes of northern seas
- eelworm
- any of various small free-living plant-parasitic roundworms
- eft
- a newt in its terrestrial stage of development
- egg
- animal reproductive body consisting of an ovum or embryo together with nutritive and protective envelopes; especially the thin-shelled reproductive body laid by e.g. female birds
- egg-laying mammal
- the most primitive mammals comprising the only extant members of the subclass Prototheria
- eggar
- moth having nonfunctional mouthparts as adults; larvae feed on tree foliage and spin egg-shaped cocoons
- egret
- any of various usually white herons having long plumes during breeding season
- Egretta caerulea
- small bluish-grey heron of the western hemisphere
- Egretta garzetta
- Old World egret
- Egretta thula
- small New World egret
- Egyptian cat
- a domestic cat of Egypt
- Egyptian cobra
- cobra used by the Pharaohs as a symbol of their power over life and death
- eider
- duck of the northern hemisphere much valued for the fine soft down of the females
- eiderdown
- down of the eider duck
- Eira barbara
- long-tailed arboreal mustelid of Central America and South America
- Elagatis bipinnulata
- streamlined cigar-shaped jack; good game fish
- eland
- either of two large African antelopes of the genus Taurotragus having short spirally twisted horns in both sexes
- Elanoides forficatus
- graceful North American black-and-white kite
- Elanus leucurus
- grey-and-white American kite of warm and tropical regions
- Elaphe guttata
- large harmless snake of southeastern United States; often on farms
- Elaphe obsoleta
- large harmless shiny black North American snake
- Elaphurus davidianus
- large Chinese deer surviving only in domesticated herds
- elapid
- any of numerous venomous fanged snakes of warmer parts of both hemispheres
- elasmobranch
- any of numerous fishes of the class Chondrichthyes characterized by a cartilaginous skeleton and placoid scales: sharks; rays; skates
- elater
- any of various widely distributed beetles
- elbow
- the joint of a mammal or bird that corresponds to the human elbow
- Electrophorus electric
- eel-shaped freshwater fish of South America having electric organs in its body
- elephant
- five-toed pachyderm
- elephant seal
- either of two large northern Atlantic earless seals having snouts like trunks
- Elops saurus
- game fish resembling the tarpon but smaller
- elver
- young eel
- elytron
- either of the horny front wings in beetles and some other insects which cover and protect the functional hind wings
- Emberiza aureola
- common in Russia and Siberia
- Emberiza citrinella
- European bunting the male being bright yellow
- Emberiza hortulana
- brownish Old World bunting often eaten as a delicacy
- Emberiza schoeniclus
- European bunting inhabiting marshy areas
- embryonic tissue
- tissue in an embryo
- emperor
- large richly colored butterfly
- encolure
- the mane of a horse
- endameba
- any ameba of the genus Endamoeba
- Endamoeba histolytica
- the parasitic ameba that causes amebic dysentery in human beings
- endoblast
- the inner germ layer that develops into the lining of the digestive and respiratory systems
- endoparasite
- any of various parasites that live in the internal organs of animals (especially intestinal worms)
- endospore-forming bacteria
- a group of true bacteria
- English bulldog
- a sturdy thickset short-haired breed with a large head and strong undershot lower jaw; developed originally in England for bull baiting
- English cocker spaniel
- a small breed with wavy silky hair; originally developed in England
- English foxhound
- an English breed slightly larger than the American foxhounds originally used to hunt in packs
- English lady crab
- crab of the English coasts
- English setter
- an English breed having a plumed tail and a soft silky coat that is chiefly white
- English springer spaniel
- a breed having typically a black-and-white coat
- English toy spaniel
- British breed having a long silky coat and rounded head with a short upturned muzzle
- Engraulis encrasicholus
- esteemed for its flavor; usually preserved or used for sauces and relishes
- Enhydra lutris
- large marine otter of northern Pacific coasts having very thick dark brown fur
- enteric bacteria
- rod-shaped Gram-negative bacteria; most occur normally or pathogenically in intestines of humans and other animals
- Enterobius vermicularis
- small threadlike worm infesting human intestines and rectum especially in children
- enterovirus
- any of a group of picornaviruses that infect the gastrointestinal tract and can spread to other areas (especially the nervous system)
- entire
- uncastrated adult male horse
- EntleBucher
- the smallest of the Sennenhunde
- entoproct
- any of various moss-like aquatic animals usually forming branching colonies; each polyp having a both mouth and anus within a closed ring of tentacles
- eoraptor
- a theropod dinosaur of the genus Eoraptor
- ephemeral
- anything short-lived, as an insect that lives only for a day in its winged form
- ephemerid
- short-lived insect
- Ephestia elutella
- small moth whose larvae feed on tobacco and other dried plant products
- Ephippiorhynchus senegalensis
- large black-and-white stork of tropical Africa; its red bill has a black band around the middle
- Epilachna varivestis
- introduced into the United States from Mexico; feeds on the foliage of the bean plant
- Epinephelus adscensionis
- found around rocky coasts or on reefs
- Epinephelus fulvus
- black-spotted usually dusky-colored fish with reddish fins
- Epstein-Barr virus
- the herpes virus that causes infectious mononucleosis; associated with specific cancers in Africa and China
- eptatretus
- a fossil hagfish of the genus Eptatretus
- Eptesicus fuscus
- rather large North American brown bat; widely distributed
- Eptesicus serotinus
- common brown bat of Europe
- Equetus lanceolatus
- black-and-white drumfish with an erect elongated dorsal fin
- Equetus pulcher
- a kind of drumfish
- equid
- hoofed mammals having slender legs and a flat coat with a narrow mane along the back of the neck
- Equus asinus
- domestic beast of burden descended from the African wild ass; patient but stubborn
- Equus caballus
- solid-hoofed herbivorous quadruped domesticated since prehistoric times
- Equus caballus gomelini
- European wild horse extinct since the early 20th century
- Equus caballus przewalskii
- wild horse of central Asia that resembles an ass; now endangered
- Equus grevyi
- zebra with less continuous stripes
- Equus hemionus
- Asiatic wild ass
- Equus hemionus hemionus
- Mongolian wild ass
- Equus kiang
- wild ass of Tibet and Mongolia
- Equus quagga
- mammal of South Africa that resembled a zebra; extinct since late 19th century
- Equus zebra zebra
- narrow-striped nearly extinct zebra of southern Africa
- Erethizon dorsatum
- porcupine of northeastern North America with barbed spines concealed in the coarse fur; often gnaws buildings for salt and grease
- Eretmochelys imbricata
- pugnacious tropical sea turtle with a hawk-like beak; source of food and the best tortoiseshell
- Erignathus barbatus
- medium-sized greyish to yellow seal with bristles each side of muzzle; of the Arctic Ocean
- Erinaceus europeaeus
- small nocturnal Old World mammal covered with both hair and protective spines
- Eriosoma lanigerum
- primarily a bark feeder on aerial parts and roots of apple and other trees
- Erithacus rubecola
- small Old World songbird with a reddish breast
- Erithacus svecicus
- songbird of northern Europe and Asia
- Erolia alpina
- small common sandpiper that breeds in northern or Arctic regions and winters in southern United States or Mediterranean regions
- Erolia minutilla
- smallest American sandpiper
- erwinia
- rod-shaped motile bacteria that attack plants
- Erythrocebus patas
- reddish long-tailed monkey of west Africa
- escallop
- edible marine bivalve having a fluted fan-shaped shell that swim by expelling water from the shell in a series of snapping motions
- escherichia
- a genus of enteric bacteria
- Escherichia coli
- a species of bacterium normally present in intestinal tract of humans and other animals; sometimes pathogenic; can be a threat to food safety
- Eschrichtius robustus
- medium-sized greyish-black whale of the northern Pacific
- Eskimo dog
- breed of heavy-coated Arctic sled dog
- Esox americanus
- small but gamy pickerel of Atlantic coastal states
- Esox lucius
- voracious piscivorous pike of waters of northern hemisphere
- Esox masquinongy
- large (60 to 80 pounds) sport fish of North America
- Esox niger
- common in quiet waters of eastern United States
- Etropus rimosus
- flounder found from North Carolina to Florida and the eastern Gulf of Mexico
- Euarctos americanus
- brown to black North American bear; smaller and less ferocious than the brown bear
- eubacteria
- a large group of bacteria having rigid cell walls; motile types have flagella
- eucaryote
- an organism with cells characteristic of all life forms except primitive microorganisms such as bacteria; i.e. an organism with `good' or membrane-bound nuclei in its cells
- Eucinostomus gula
- silvery mojarra found along sandy shores of the western Atlantic
- Euderma maculata
- a large bat of the southwestern United States having spots and enormous ears
- euglena
- minute single-celled green freshwater organism having a single flagella; often classed as algae
- euglenid
- marine and freshwater green or colorless flagellate organism
- Eumeces callicephalus
- frequents oak and pine habitats in rocky mountainous areas of United States southwest and Mexico
- Eumeces skiltonianus
- found in western North American grasslands and open woodlands
- Eumetopias jubatus
- largest sea lion; of the northern Pacific
- Eunectes murinus
- large arboreal boa of tropical South America
- Euopean hoopoe
- pinkish-brown hoopoe with black-and-white wings
- Euphagus carilonus
- North American blackbird whose bluish-black plumage is rusty-edged in the fall
- Euphausia pacifica
- food for jellyfish
- Euphractus sexcinctus
- Argentine armadillo with six movable bands and hairy underparts
- Euproctis chrysorrhoea
- white furry-bodied European moth with a yellow tail tuft
- Euproctis phaeorrhoea
- small brown and white European moth introduced into eastern United States; pest of various shade and fruit trees
- Eurasian badger
- a variety of badger native to Europe and Asia
- Eurasian green toad
- Eurasian toad with variable chiefly green coloring
- Eurasian kingfisher
- small kingfisher with greenish-blue and orange plumage
- Eurasian otter
- otter found in Europe and Asia
- European black grouse
- large northern European grouse that is black with a lyre-shaped tail
- European blackbird
- common black European thrush
- European bream
- European freshwater fish having a flattened body and silvery scales; of little value as food
- European catfish
- large elongated catfish of central and eastern Europe
- European corn borer moth
- native to Europe; in America the larvae bore into the stem and crown of corn and other plants
- European cuckoo
- common cuckoo of Europe having a distinctive two-note call; lays eggs in the nests of other birds
- European fire salamander
- a kind of European salamander
- European house cricket
- lives in human dwellings; naturalized in parts of America
- European lemming
- notable for mass migrations even into the sea where many drown
- European magpie
- a common magpie of Eurasia
- European nuthatch
- a kind of nuthatch
- European sandpiper
- a variety of sandpiper
- European sole
- highly valued as food
- European spider crab
- a large spider crab of Europe
- European swift
- common European bird with a shrieking call that nests chiefly about eaves of buildings or on cliffs
- European toad
- common toad of Europe
- European tortoise
- small land tortoise of southern Europe
- European water ouzel
- a water ouzel of Europe
- European water shrew
- widely distributed Old World water shrew
- European wolf spider
- large southern European spider once thought to be the cause of tarantism (uncontrollable bodily movement)
- European wood mouse
- nocturnal yellowish-brown mouse inhabiting woods and fields and gardens
- eurypterid
- large extinct scorpion-like arthropod considered related to horseshoe crabs
- Eutamius sibiricus
- terrestrial Siberian squirrel
- eutherian
- mammals having a placenta; all mammals except monotremes and marsupials
- Euthynnus pelamis
- oceanic schooling tuna of considerable value in Pacific but less in Atlantic; reaches 75 pounds; very similar to if not the same as oceanic bonito
- ewe
- female sheep
- Exmoor
- horned sheep of Devon; valued for mutton
- Exmoor
- stocky breed of pony with a fawn-colored nose
- external gill
- occurs in some mollusks and in tadpoles and other immature amphibians
- eyas
- an unfledged or nestling hawk
- eyecup
- (embryology) a two-walled cuplike depression that develops into the pigmented and sensory layers of the retina
- fairy shrimp
- small freshwater branchiopod having a transparent body with many appendages; swims on its back
- fairy swallow
- fancy domestic pigeon having blue-and-white plumage and heavily muffed feet
- Falco columbarius
- small falcon of Europe and America having dark plumage with black-barred tail; used in falconry
- Falco peregrinus
- a widely distributed falcon formerly used in falconry
- Falco rusticolus
- large and rare Arctic falcon having white and dark color phases
- Falco sparverius
- small North American falcon
- Falco subbuteo
- small Old World falcon formerly trained and flown at small birds
- Falco tinnunculus
- small Old World falcon that hovers in the air against a wind
- falcon
- diurnal birds of prey having long pointed powerful wings adapted for swift flight
- falcon-gentil
- female falcon especially a female peregrine falcon
- fall cankerworm
- green or brown white-striped looper; larva of Alsophila pometaria
- false saber-toothed tiger
- North American cat of the Miocene and Pliocene; much earlier and less specialized than members of the genus Smiledon
- false scorpion
- small nonvenomous arachnid resembling a tailless scorpion
- false vampire
- any New or Old World carnivorous bat erroneously thought to suck blood but in fact feeding on insects
- family Acanthisittidae
- alternative names for the family comprising the New Zealand wrens
- family Acanthuridae
- surgeonfishes
- family Acaridae
- mites
- family Accipitridae
- hawks; Old World vultures; kites; harriers; eagles
- family Acipenseridae
- sturgeons
- family Actinomycetaceae
- filamentous anaerobic bacteria
- family Adelgidae
- plant lice
- family Aegypiidae
- in some classifications considered the family comprising the Old World vultures which are more often included in the family Accipitridae
- family Aepyornidae
- coextensive with the order Aepyorniformes
- family Agamidae
- an Old World reptile family of Sauria
- family Agonidae
- poachers
- family Ailuropodidae
- in some classifications considered the family comprising the giant pandas
- family Akeridae
- bubble shells
- family Alaudidae
- larks
- family Albulidae
- bonefish
- family Alcedinidae
- kingfishers
- family Alcidae
- web-footed diving seabirds of northern seas: auks; puffins; guillemots; murres; etc.
- family Aleyrodidae
- whiteflies
- family Alligatoridae
- alligators; caimans
- family Alopiidae
- thresher sharks
- family Ambystomatidae
- New World salamanders
- family Ameiuridae
- North American catfishes
- family Amiidae
- only the bowfins
- family Ammodytidae
- sand lances
- family Amphisbaenidae
- worm lizards
- family Amphiumidae
- congo snakes
- family Anabantidae
- small freshwater spiny-finned fishes of Africa and southern Asia
- family Anarhichadidae
- wolffishes
- family Anatidae
- swimming birds having heavy short-legged bodies and bills with a horny tip: swans; geese; ducks
- family Ancylidae
- freshwater gastropod
- family Ancylostomatidae
- hookworms
- family Andrenidae
- a large family of solitary short-tongued bees most of which burrow in the ground
- family Anguidae
- alligator lizards
- family Anguillidae
- eels that live in fresh water as adults but return to the sea to spawn
- family Anhimidae
- screamers
- family Anhingidae
- snakebirds
- family Anniellidae
- legless lizards
- family Anobiidae
- deathwatch beetles
- family Anomalopidae
- a family of fish including: flashlight fishes
- family Anomiidae
- saddle oysters
- family Antedonidae
- feather stars
- family Antennariidae
- frogfishes; tropical spiny-finned marine fishes having large nearly vertical mouths; related to toadfishes and anglers
- family Antilocapridae
- comprising only the pronghorns
- family Aphididae
- small soft-bodied plant lice
- family Apidae
- honeybees; carpenter bees; bumblebees
- family Aplodontiidae
- mountain beavers
- family Aplysiidae
- sea hares
- family Apodidae
- swifts; in former classifications included in the order Coraciiformes
- family Apogonidae
- bright-colored marine fishes that incubate eggs in the mouth
- family Apterygidae
- coextensive with the order Apterygiformes
- family Arcellidae
- soil and freshwater protozoa; cosmopolitan in distribution
- family Arcidae
- ark shells
- family Arctiidae
- tiger moths
- family Ardeidae
- herons; egrets; night herons; bitterns
- family Argasidae
- soft ticks
- family Argentinidae
- small marine soft-finned fishes with long silvery bodies; related to salmons and trouts
- family Argiopidae
- spiders that spin orb webs; cosmopolitan in distribution
- family Argonautidae
- represented solely by the genus Argonauta
- family Ariidae
- sea catfishes
- family Armadillidiidae
- pill bugs
- family Artamidae
- wood swallows
- family Ascaphidae
- family of one species of frog: tailed frog
- family Ascaridae
- large roundworms parasitic in intestines of vertebrates
- family Asilidae
- robber flies
- family Astacidae
- crayfish
- family Atherinidae
- small spiny-finned fishes of both salt and fresh water
- family Athiorhodaceae
- small motile sulphur bacteria
- family Atrichornithidae
- scrubbirds
- family Atropidae
- booklice
- family Aulostomidae
- trumpetfishes
- family Babesiidae
- piroplasms and cattle pathogens
- family Bacillaceae
- typically rod-shaped usually Gram-positive bacteria that produce endospores
- family Bacteroidaceae
- family of bacteria living usually in the alimentary canal or on mucous surfaces of warm-blooded animals; sometimes associated with acute infective processes
- family Balaenicipitidae
- shoebills
- family Balaenidae
- right whales
- family Balaenopteridae
- rorquals; blue whales
- family Balanidae
- stalkless barnacles
- family Balistidae
- triggerfishes
- family Bangiaceae
- a family of protoctist
- family Bathyergidae
- mole rats; sand rats
- family Batrachoididae
- toadfishes; related to anglers and batfishes
- family Belemnitidae
- family of extinct Mesozoic cephalopods
- family Belonidae
- ferocious fishes of warm regions resembling but unrelated to the freshwater gars
- family Belostomatidae
- water bugs
- family Bittacidae
- a family of predacious tropical insects of the order Mecoptera
- family Blattidae
- domestic cockroaches
- family Blenniidae
- a family of fish including: combtooth blennies
- family Boidae
- boas and pythons
- family Bombycidae
- Chinese silkworm moth
- family Bombycillidae
- a family of birds of the suborder Oscines
- family Bombyliidae
- bee flies
- family Bothidae
- a family of fish of the order Heterosomata
- family Bovidae
- true antelopes; cattle; oxen; sheep; goats
- family Bradypodidae
- a family of edentates comprising the true sloths
- family Bramidae
- deep-bodied percoid fishes of the open seas
- family Branchiobdellidae
- small annelid worms with the posterior end modified into an adhesive sucker; especially formerly regarded as modified leeches
- family Branchiostegidae
- small family of marine fishes having covered gills
- family Branchiostomidae
- lancelets
- family Brevicipitidae
- narrow-mouthed toads and sheep frogs; some burrow and some are arboreal; found worldwide
- family Brotulidae
- chiefly deep-sea fishes related to the Ophidiidae
- family Bruchidae
- seed beetles
- family Buccinidae
- whelks
- family Bucconidae
- puffbirds
- family Bucerotidae
- hornbills
- family Bufonidae
- true toads
- family Burhinidae
- large wading birds resembling the plovers: stone curlews
- family Caeciliadae
- coextensive with the order Gymnophiona: legless amphibians
- family Caenolestidae
- small marsupials of southern South America
- family Callionymidae
- dragonets
- family Calliphoridae
- blowflies
- family Callithricidae
- marmosets
- family Camelidae
- camels and llamas and vicunas
- family Cancridae
- many of the best known edible crabs
- family Canidae
- dogs; wolves; jackals; foxes
- family Capitonidae
- barbets
- family Caprimulgidae
- goatsuckers
- family Caproidae
- boarfishes
- family Capromyidae
- coypus
- family Capsidae
- leaf bugs
- family Carabidae
- ground beetles
- family Carangidae
- large family of narrow-bodied marine food fishes with widely forked tails; chiefly of warm seas
- family Carapidae
- pearlfishes: related to the Brotulidae
- family Carcharhinidae
- largest family of living sharks; found worldwide especially in tropical waters; dorsal fin lacks spines: requiem sharks including tiger sharks and soupfin sharks
- family Cardiidae
- somewhat heart-shaped sand-burrowing bivalve mollusks
- family Cariamidae
- crane-like South American wading birds
- family Castoridae
- beavers
- family Casuaridae
- a family of large ostrich-like birds including cassowaries
- family Cathartidae
- condors; turkey buzzards; king vultures
- family Catostomidae
- suckers; closely related to the family Cyprinidae
- family Caviidae
- a family of Hystricomorpha
- family Cebidae
- all the New World monkeys except marmosets and tamarins
- family Cecidomyidae
- gall midges
- family Centrarchidae
- sunfish family
- family Centriscidae
- shrimpfishes
- family Centropomidae
- a family of fish or the order Perciformes including robalos
- family Cephalobidae
- a family of Nematoda
- family Cerambycidae
- long-horned beetles
- family Ceratodontidae
- lungfishes having hornlike ridges on the teeth
- family Ceratopogonidae
- biting midges; sand flies
- family Ceratopsidae
- American ceratopsian dinosaurs
- family Cercopidae
- froghoppers or spittlebugs
- family Cercopithecidae
- Old World monkeys: guenon; baboon; colobus monkey; langur; macaque; mandrill; mangabey; patas; proboscis monkey
- family Certhiidae
- creepers
- family Cervidae
- deer: reindeer; moose or elks; muntjacs; roe deer
- family Cestidae
- coextensive with the order Cestida; ctenophores having a greatly flattened and elongated body
- family Cetorhinidae
- in some older classifications considered the family of the basking sharks
- family Chaetodontidae
- butterfly fishes
- family Chalcididae
- an arthropod family including: chalcidflies
- family Chamaeleontidae
- Old World chameleons; in some classifications they are considered a superfamily of Sauria
- family Characeae
- green algae superficially resembling horsetail ferns: stoneworts
- family Characidae
- tropical freshwater fishes of Africa and South America and Central America
- family Characinidae
- former name of the Characidae
- family Charadriidae
- plover family
- family Cheloniidae
- green turtles; hawksbills
- family Chelydridae
- snapping turtles
- family Chermidae
- jumping plant lice
- family Chimaeridae
- a family of Holocephali
- family Chinchillidae
- small bushy-tailed South American burrowing rodents
- family Chironomidae
- midges
- family Chlamydiaceae
- Gram-negative parasites in warm-blooded vertebrates
- family Chlamydomonadaceae
- green algae some of which are colored red by hematochrome
- family Chlorophthalmidae
- small family of soft-finned bottom-dwellers with large eyes; relatives of lizardfishes
- family Chrysochloridae
- golden moles
- family Chrysomelidae
- leaf beetles
- family Chrysopidae
- green lacewings
- family Cicadellidae
- leafhoppers
- family Cicadidae
- cicadas
- family Cichlidae
- cichlids
- family Cicindelidae
- tiger beetles
- family Ciconiidae
- storks
- family Cimicidae
- wingless flat-bodied bloodsucking insects
- family Cinclidae
- water ouzels
- family Cleridae
- beetles that prey on other insects
- family Clinidae
- viviparous blennies of temperate and tropical seas
- family Clupeidae
- herrings; shad; sardines; etc.
- family Cobitidae
- loaches
- family Coccidae
- scale insects
- family Coccinellidae
- the ladybugs
- family Coerebidae
- the honeycreepers
- family Colubridae
- nonvenomous snakes; about two-thirds of all living species
- family Columbidae
- doves and pigeons
- family Comatulidae
- former usage synonymous with Antedonidae
- family Congridae
- marine eels
- family Coraciidae
- rollers
- family Cordylidae
- small family of spiny ovoviviparous African lizards
- family Coregonidae
- soft-finned fishes comprising the freshwater whitefishes; formerly included in the family Salmonidae
- family Coreidae
- squash bugs and leaf-footed bugs
- family Corixidae
- water bugs
- family Corvidae
- crow; raven; rook; jackdaw; chough; magpie; jay
- family Corydalidae
- dobsons
- family Corynebacteriaceae
- a large family of mostly Gram-positive and aerobic and nonmotile rod-shaped bacteria of the order Eubacteriales
- family Coryphaenidae
- large active pelagic percoid fish
- family Cotingidae
- cotingas; umbrella birds
- family Cottidae
- sculpins
- family Cracidae
- curassows; guans; chachalacas
- family Cracticidae
- Australian birds formerly included in the family Laniidae
- family Crangonidae
- shrimps
- family Cricetidae
- mostly small New World rodents including New World mice and lemmings and voles and hamsters
- family Crocodylidae
- true crocodiles
- family Crotalidae
- New World vipers: pit vipers
- family Cryptobranchidae
- large aquatic salamanders: hellbenders; giant salamanders
- family Cryptocercidae
- a family of Blattodea
- family Ctenizidae
- large burrowing spiders
- family Cuculidae
- includes cuckoo; ani; roadrunner
- family Culicidae
- mosquitoes
- family Curculionidae
- true weevils: snout beetles
- family Cuterebridae
- New World botflies
- family Cyclopteridae
- lumpfishes
- family Cymatiidae
- tritons
- family Cynipidae
- a family of Hymenoptera
- family Cynocephalidae
- a family of Dermoptera
- family Cynoglossidae
- tonguefishes
- family Cypraeidae
- family of marine gastropods comprising the cowries
- family Cyprinidae
- a family of fish including: carp; tench; roach; rudd; dace
- family Cyprinodontidae
- large family of small soft-finned fishes; killifishes; flagfishes; swordtails; guppies
- family Dactylopiidae
- cochineal insects
- family Dactylopteridae
- flying gurnards
- family Dactyloscopidae
- sand stargazers
- family Danaidae
- small family of usually tropical butterflies: monarch butterflies
- family Dasyatidae
- sting rays
- family Dasypodidae
- armadillos
- family Dasyproctidae
- agoutis and pacas
- family Dasyuridae
- dasyures; native cats; pouched mice; banded anteaters; Tasmanian devils
- family Daubentoniidae
- comprising solely the aye-aye
- family Delphinidae
- dolphins
- family Dendrocolaptidae
- woodhewers or woodcreepers
- family Dermestidae
- carpet beetles
- family Dermochelyidae
- sea turtles
- family Desmidiaceae
- unicellular algae
- family Desmodontidae
- true vampire bats
- family Diaspididae
- armored scales
- family Dicamptodontidae
- large and small highly aquatic salamanders
- family Didelphidae
- opossums
- family Dinornithidae
- moas
- family Diodontidae
- spiny puffers
- family Diomedeidae
- albatrosses
- family Dipodidae
- Old World jerboas
- family Discoglossidae
- family of Old World toads having a fixed disklike tongue
- family Doliolidae
- oceanic tunicates
- family Dracunculidae
- greatly elongated roundworm
- family Drepanididae
- Hawaiian honeycreepers
- family Dromaeosauridae
- swift-running bipedal dinosaurs
- family Drosophilidae
- fruit flies
- family Dugongidae
- a family of mammals of order Sirenia including dugongs and Steller's sea cow
- family Dytiscidae
- water beetles
- family Echeneididae
- fishes having a sucking disk on the head for clinging to other fishes and to ships
- family Edaphosauridae
- a family of reptiles of the order Pelycosauria
- family Eimeriidae
- a family of protoctist in the order Coccidia
- family Elapidae
- cobras; kraits; mambas; coral snakes; Australian taipan and tiger snakes
- family Elateridae
- click beetles and certain fireflies
- family Electrophoridae
- small family comprising the electric eels
- family Eleotridae
- sleepers
- family Elephantidae
- elephants
- family Elopidae
- tarpons and ladyfishes
- family Embiotocidae
- viviparous percoid fishes comprising the surf fishes
- family Emydidae
- box and water turtles
- family Endamoebidae
- a large family of endoparasitic amebas that invade the digestive tract
- family Engraulidae
- anchovies
- family Enterobacteriaceae
- a large family of Gram-negative rod-shaped bacteria of the order Eubacteriales
- family Ephemeridae
- mayflies
- family Ephippidae
- small family comprising the spadefishes
- family Equidae
- horses; asses; zebras; extinct animals
- family Erethizontidae
- New World arboreal porcupines
- family Erinaceidae
- true hedgehogs
- family Eschrichtiidae
- comprising only the grey whales
- family Esocidae
- pikes; pickerels; muskellunges
- family Euglenaceae
- considered green algae
- family Eurylaimidae
- coextensive with the suborder Eurylaimi
- family Exocoetidae
- flying fishes; closely related to the halfbeaks
- family Falconidae
- a family of birds of the order Falconiformes
- family Fasciolidae
- a family of Trematoda
- family Felidae
- cats; wildcats; lions; leopards; cheetahs; saber-toothed tigers
- family Filariidae
- threadlike roundworms
- family Fissurellidae
- marine limpets
- family Fistulariidae
- cornetfishes
- family Forficulidae
- typical earwigs
- family Formicariidae
- antbirds
- family Formicidae
- ants
- family Fregatidae
- frigate birds
- family Fringillidae
- finches: goldfinches; bullfinches; chaffinches; siskins; canaries; cardinals; grosbeaks; crossbills; linnets; buntings
- family Fucaceae
- small family of brown algae: gulfweeds; rockweeds
- family Fulgoridae
- plant hoppers: lantern flies
- family Furnariidae
- e.g. ovenbirds
- family Gadidae
- large family of important mostly marine food fishes
- family Galbulidae
- jacamars
- family Gasterophilidae
- horse botflies
- family Gasterosteidae
- sticklebacks
- family Gavialidae
- gavials
- family Gavidae
- loon family
- family Gekkonidae
- geckos
- family Gelechiidae
- important economic pests
- family Gempylidae
- snake mackerels
- family Geometridae
- measuring worms
- family Geomyidae
- North American pocket gophers
- family Geophilidae
- small extremely elongate centipedes that live in earth
- family Gerreidae
- mojarras
- family Gerrididae
- an arthropod family that includes water striders
- family Gigartinaceae
- a family of protoctist
- family Giraffidae
- giraffes
- family Glareolidae
- Old World shorebirds: pratincoles and coursers
- family Gliridae
- dormice and other Old World forms
- family Globigerinidae
- a family of protoctists
- family Glossinidae
- flies closely related to the Muscidae: tsetse flies
- family Gobiesocidae
- clingfishes
- family Gobiidae
- gobies
- family Gomphotheriidae
- elephants extinct since the Pleistocene
- family Gonorhynchidae
- coextensive with the genus Gonorhynchus
- family Gracilariidae
- leaf miners
- family Gruidae
- cranes
- family Gryllidae
- crickets
- family Gyrinidae
- whirligig beetles
- family Hadrosauridae
- duck-billed dinosaurs; upper Cretaceous
- family Haematopodidae
- oystercatchers
- family Haemoproteidae
- bird parasites
- family Haemulidae
- grunts
- family Halictidae
- a family of small solitary bees; many are valuable pollinators for agriculture
- family Haliotidae
- abalones
- family Helicidae
- land snails including the common edible snail and some pests
- family Helodermatidae
- only known venomous lizards
- family Hemerobiidae
- brown lacewings
- family Hemiprocnidae
- tree swifts
- family Hemiramphidae
- halfbeaks; marine and freshwater fishes closely related to the flying fishes but not able to glide
- family Heteromyidae
- small New World burrowing mouselike rodents with fur-lined cheek pouches and hind limbs and tail adapted to leaping; adapted to desert conditions: pocket mice; kangaroo mice; kangaroo rats
- family Hexagrammidae
- greenlings
- family Hexanchidae
- primitive sharks
- family Hippoboscidae
- winged or wingless dipterans: louse flies
- family Hippopotamidae
- hippopotami
- family Hipposideridae
- Old World leafnose bats
- family Hirudinidae
- a family of Hirudinea
- family Hirundinidae
- swallows and martins
- family Holocentridae
- squirrelfishes and soldierfishes
- family Holothuridae
- a family of Holothuroidea
- family Homaridae
- large-clawed lobsters
- family Hominidae
- modern man and extinct immediate ancestors of man
- family Hyaenidae
- hyenas
- family Hydrobatidae
- storm petrels
- family Hydrochoeridae
- capybara
- family Hydrophidae
- sea snakes
- family Hylidae
- the amphibian family of tree frogs
- family Hylobatidae
- used in some classifications for the lesser apes (gibbons and siamangs); sometimes considered a subfamily of Pongidae
- family Hyperodontidae
- beaked whales; in some especially former classifications included in the family Physeteridae
- family Hypodermatidae
- warble flies
- family Hystricidae
- Old World porcupines
- family Ichneumonidae
- ichneumon flies
- family Ichthyosauridae
- later ichthyosaurs of the Jurassic and Cretaceous; widely distributed in both hemispheres
- family Icteridae
- American orioles; American blackbirds; bobolinks; meadowlarks
- family Iguanidae
- New World lizards
- family Iguanodontidae
- iguanodons
- family Indicatoridae
- honey guides
- family Indriidae
- a family of Lemuroidea
- family Irenidae
- a family of birds of the suborder Oscines
- family Istiophoridae
- sailfishes; spearfishes; marlins
- family Isuridae
- in some classifications another name for the family Lamnidae
- family Ixodidae
- hard ticks
- family Jassidae
- family of small leafhoppers coextensive with the Cicadellidae and not distinguished from it in some classifications
- family Kalotermitidae
- primitive termites of warm regions
- family Kasuwonidae
- in some classifications considered a separate family comprising the oceanic bonitos
- family Kinosternidae
- mud turtles; musk turtles
- family Kyphosidae
- sea chubs
- family Labridae
- wrasses
- family Lacertidae
- Old World lizards
- family Lactobacteriaceae
- lactic acid bacteria and important pathogens; bacteria that ferment carbohydrates chiefly into lactic acid
- family Laminariaceae
- large family of marine brown algae including many economically important large kelps chiefly of northern waters
- family Lamnidae
- oceanic sharks
- family Lampridae
- opahs
- family Lampyridae
- fireflies
- family Laniidae
- shrikes
- family Lanthanotidae
- stout-bodied lizards
- family Laricariidae
- armored catfish
- family Laridae
- gull family: gulls and terns
- family Lasiocampidae
- tent caterpillars; eggars; lappet moths
- family Latimeridae
- extinct except for the coelacanth
- family Leiopelmatidae
- primitive New Zealand frogs
- family Lemuridae
- typical lemurs; of Madagascar
- family Lepadidae
- goose barnacles
- family Lepismatidae
- firebrats
- family Lepisosteidae
- comprises the genus Lepisosteus
- family Leporidae
- hares and rabbits
- family Leptodactylidae
- New World frogs; in some classifications essentially coextensive with the family Bufonidae
- family Leptotyphlopidae
- blind snakes
- family Limacidae
- slugs
- family Limulidae
- horseshoe crabs
- family Liparididae
- snailfishes
- family Lithodidae
- deep-sea crabs of cold waters
- family Littorinidae
- periwinkles
- family Lobotidae
- tripletails
- family Locustidae
- short-horned grasshoppers; true locusts
- family Lophiidae
- large-headed marine fishes comprising the anglers
- family Lorisidae
- slow-moving omnivorous nocturnal primates of tropical Asia; usually tailless
- family Lucanidae
- stag beetles
- family Lutjanidae
- snappers
- family Luvaridae
- louvars
- family Lycaenidae
- family of small usually brilliantly colored butterflies; males have short forelegs
- family Lycosidae
- wolf spiders
- family Lygaeidae
- lygaeid bugs
- family Lymantriidae
- tussock moths
- family Machilidae
- jumping bristletails
- family Macropodidae
- kangaroos; wallabies
- family Macrorhamphosidae
- bellows fishes
- family Macrouridae
- grenadiers
- family Majidae
- spider crabs
- family Malacanthidae
- short-headed marine fishes; often brightly colored
- family Manidae
- coextensive with the order Pholidota
- family Manteidae
- mantises
- family Mantispidae
- mantispids
- family Mastodontidae
- extinct family: mastodons
- family Mastotermitidae
- primitive termites
- family Megachilidae
- leaf-cutting and mason bees
- family Megadermatidae
- Old World false vampire bats
- family Megalonychidae
- mammal family consisting of the two-toed sloths
- family Megalosauridae
- megalosaurs
- family Megapodiidae
- megapodes
- family Megatheriidae
- extinct ground sloths
- family Meleagrididae
- turkeys and some extinct forms
- family Meliphagidae
- honey eaters
- family Meloidae
- blister beetles
- family Membracidae
- plant hoppers: treehoppers
- family Menuridae
- lyrebirds
- family Meropidae
- bee-eaters
- family Micrococcaceae
- spherical or elliptical usually aerobic eubacteria that produce yellow or orange or red pigment; includes toxin-producing forms as well as harmless commensals and saprophytes
- family Microdesmidae
- worm fish
- family Mimidae
- sometimes considered a subfamily of Troglodytidae: mockingbirds; catbirds; thrashers
- family Mobulidae
- large rays lacking venomous spines: mantas
- family Molidae
- ocean sunfishes
- family Molossidae
- mastiff bats; freetail bats
- family Momotidae
- a family of birds of the order Coraciiformes
- family Monocanthidae
- filefishes
- family Monodontidae
- narwhals
- family Motacillidae
- pipits and wagtails
- family Mugilidae
- grey mullets
- family Mullidae
- goatfishes or red mullets
- family Muraenidae
- marine eels
- family Muridae
- originally Old World rats now distributed worldwide; distinguished from the Cricetidae by typically lacking cheek pouches
- family Muscicapidae
- Old World (true) flycatchers
- family Muscidae
- two-winged flies especially the housefly
- family Musophagidae
- touracos
- family Mustelidae
- weasels; polecats; ferrets; minks; fishers; otters; badgers; skunks; wolverines; martens
- family Mutillidae
- a family of wasps
- family Myacidae
- soft-shell clams
- family Mycetophylidae
- fungus gnats
- family Mycobacteriaceae
- a family of bacteria
- family Mycoplasmataceae
- pleomorphic Gram-negative nonmotile microorganism similar to both viruses and bacteria; parasitic in mammals
- family Myctophidae
- deep-sea fishes comprising the lantern fishes
- family Myliobatidae
- eagle rays
- family Mylodontidae
- extinct South American edentates
- family Myrmecophagidae
- New World anteaters
- family Myrmeleontidae
- antlions
- family Mysidae
- small shrimp-like crustaceans
- family Mytilidae
- marine mussels
- family Myxinidae
- slime-producing marine animals: hagfishes
- family Myxobacteriaceae
- bacteria living mostly in soils and on dung
- family Naticidae
- moonshells
- family Nautilidae
- spiral-shelled cephalopods
- family Nephropsidae
- in some classifications coextensive with the Homaridae
- family Nepidae
- water scorpions
- family Neritidae
- neritids
- family Nitrobacteriaceae
- usually rod-shaped bacteria that oxidize ammonia or nitrites: nitrobacteria
- family Noctuidae
- cutworms; armyworms
- family Nostocaceae
- blue-green algae
- family Notonectidae
- aquatic carnivorous insects
- family Notoryctidae
- pouched moles
- family Nummulitidae
- a family of fossil protoctists
- family Nymphalidae
- large beautifully colored butterflies
- family Ochotonidae
- pikas and extinct forms
- family Octopodidae
- a family of Octopoda
- family Odobenidae
- walruses and extinct forms
- family Odontaspididae
- sand sharks; in some classifications coextensive with family Carcharhinidae
- family Oedogoniaceae
- filamentous green algae
- family Ogcocephalidae
- batfishes: sluggish bottom-dwelling spiny fishes
- family Oniscidae
- a family of Isopoda
- family Ophidiidae
- eellike marine fishes
- family Ophiodontidae
- fishes closely related to greenlings
- family Opisthocomidae
- comprising the hoatzins
- family Opisthognathidae
- jawfishes
- family Orchestiidae
- beach fleas
- family Orectolobidae
- nurse sharks and carpet sharks
- family Oriolidae
- Old World orioles
- family Ornithorhynchidae
- platypus
- family Orycteropodidae
- aardvarks
- family Oscillatoriaceae
- blue green algae
- family Osmeridae
- smelts
- family Osteoglossidae
- a family of large fishes that live in freshwater; includes bandfish and bonytongues
- family Ostraciontidae
- boxfishes
- family Ostreidae
- oysters
- family Otariidae
- eared seals: sea lions and fur seals
- family Otididae
- bustards
- family Oxyuridae
- pinworms
- family Paguridae
- hermit crabs
- family Palaemonidae
- prawns
- family Palinuridae
- spiny lobsters
- family Pandionidae
- ospreys
- family Panorpidae
- a family of insects of the order Mecoptera
- family Paradisaeidae
- birds of paradise
- family Paridae
- titmice and chickadees
- family Parulidae
- New World warblers
- family Passeridae
- true sparrows: Old world birds formerly considered weaverbirds
- family Patellidae
- marine limpets
- family Pectinidae
- scallops
- family Pediculidae
- true lice: human lice and related forms
- family Pelecanidae
- pelicans
- family Pelecanoididae
- diving petrels
- family Pelobatidae
- the amphibian family of spadefoot toads
- family Pempheridae
- sweepers
- family Peneidae
- tropical prawns
- family Pennatulidae
- sea pens
- family Peramelidae
- bandicoots
- family Percidae
- active freshwater fishes; true perches and pike perches
- family Percophidae
- percoid flatheads
- family Peridiniidae
- marine and freshwater dinoflagellates
- family Peripatidae
- a family of Onychophora
- family Peripatopsidae
- a family of Onychophora
- family Petromyzontidae
- lampreys
- family Phaethontidae
- tropicbirds
- family Phalacrocoracidae
- cormorants
- family Phalangeridae
- phalangers; koalas
- family Phalangiidae
- a family of Phalangida
- family Phalaropidae
- phalaropes
- family Phasianidae
- pheasants; quails; partridges
- family Phasmatidae
- stick insects
- family Phocidae
- earless seals
- family Phoenicopteridae
- flamingos
- family Phoeniculidae
- wood hoopoes
- family Pholadidae
- a family of Bivalvia
- family Pholididae
- a family of fish of suborder Blennioidea
- family Phthiriidae
- crab lice
- family Phyllidae
- leaf insects
- family Phyllostomatidae
- New World leaf-nosed bats
- family Phylloxeridae
- plant lice
- family Physeteridae
- sperm whales
- family Physidae
- freshwater snails
- family Picidae
- woodpeckers
- family Pieridae
- arthropod family including cabbage butterflies; sulphur butterflies
- family Pinnotheridae
- tiny soft-bodied crabs
- family Pipidae
- tongueless frogs
- family Pipridae
- manakins
- family Pittidae
- pittas
- family Plasmodiidae
- malaria parasites
- family Plataleidae
- spoonbills
- family Platanistidae
- river dolphins
- family Platycephalidae
- scorpaenoid flatheads
- family Plethodontidae
- small mostly terrestrial New World salamanders having neither lungs nor gills as adults
- family Pleurobrachiidae
- sea gooseberries
- family Pleuronectidae
- righteye flounders
- family Ploceidae
- weaverbirds
- family Podargidae
- frogmouths
- family Podicipedidae
- coextensive with the order Podicipitiformes
- family Poeciliidae
- topminnows
- family Polynemidae
- threadfins
- family Polyodontidae
- paddlefishes
- family Polypedatidae
- Old World tree frogs
- family Pomacentridae
- damselfishes
- family Pomatomidae
- food and game fishes related to pompanos
- family Pongidae
- usually considered as comprising orangutans; gorillas; chimpanzees; and sometimes gibbons
- family Porcellionidae
- sow bugs
- family Portunidae
- swimming crabs
- family Potamogalidae
- otter shrews
- family Priacanthidae
- small carnivorous percoid fishes found worldwide in tropical seas
- family Pristidae
- large primitive rays with elongated snouts
- family Procaviidae
- includes all recent members of the order Hyracoidea
- family Procellariidae
- petrels; fulmars; shearwaters
- family Procyonidae
- raccoons; coatis; cacomistles; kinkajous; and sometimes pandas
- family Proteidae
- mud puppies
- family Prunellidae
- hedge sparrow
- family Pseudococcidae
- scalelike insects: mealybugs
- family Pseudomonodaceae
- rod-shaped Gram-negative bacteria; include important plant and animal pathogens
- family Psittacidae
- coextensive with the order Psittaciformes
- family Psocidae
- a family of small soft-bodied insects that feed on decaying vegetation; related to booklice
- family Psophiidae
- trumpeters
- family Psychodidae
- very small two-winged flies with hairy wings that develop in moss and damp vegetable matter: sand flies
- family Pteriidae
- pearl oysters
- family Pteroclididae
- sandgrouses
- family Pterodactylidae
- a reptile family in the order Pterosauria
- family Ptilonorhynchidae
- bowerbirds
- family Pulicidae
- many common fleas attacking humans and domestic animals
- family Pygopodidae
- Australian and Tasmanian lizards
- family Pyralididae
- bee moths; corn borers; flour moths
- family Pyrrhocoridae
- firebugs
- family Pythonidae
- in some classifications a family separate from Boidae comprising Old World boas
- family Rachycentridae
- family of pelagic fishes containing solely the cobia
- family Rajidae
- bottom-dwelling tropical rays: skates
- family Rallidae
- rails; crakes; gallinules; coots
- family Ramphastidae
- toucans
- family Ranidae
- a family nearly cosmopolitan in distribution: true frogs
- family Raphidae
- extinct dodos and solitaires
- family Raphidiidae
- a family of arthropods of the suborder Megaloptera, including snakeflies
- family Recurvirostridae
- long-legged shorebirds
- family Reduviidae
- assassin bugs
- family Regalecidae
- ribbonfishes
- family Rheidae
- a family of birds coextensive with the order Rheiformes
- family Rhincodontidae
- small-toothed sharks comprising only one species
- family Rhinobatidae
- primitive rays with guitar-shaped bodies
- family Rhinocerotidae
- rhinoceroses
- family Rhinolophidae
- Old World leaf-nosed bats
- family Rhinotermitidae
- large widely distributed family of termites of temperate to tropical regions
- family Rhizobiaceae
- a small family of rod-shaped bacteria
- family Rhodymeniaceae
- a family of protoctist
- family Rickettsiaceae
- microorganism resembling bacteria inhabiting arthropod tissues but capable of causing disease in vertebrates
- family Rynchopidae
- coextensive with the genus Rynchops: skimmers
- family Sagittariidae
- secretary birds
- family Salamandridae
- salamanders
- family Salmonidae
- salmon and trout
- family Salpidae
- a small family of tunicates in the class Thaliacea
- family Sarcoptidae
- small whitish mites
- family Saturniidae
- important and widely distributed family of moths including some of the largest insects known
- family Satyridae
- a widely distributed family of butterflies common near the edges of woods
- family Scarabaeidae
- scarab or dung beetles
- family Scaridae
- parrotfishes
- family Schistosomatidae
- a family of Trematoda
- family Schizophyceae
- former terms for Cyanophyceae
- family Sciaenidae
- warm-water marine fishes including the drums and grunts and croakers and sea trout
- family Sciaridae
- fungus gnats
- family Scincidae
- skinks
- family Sciuridae
- a mammal family of true squirrels including: ground squirrels; marmots; chipmunks; flying squirrels; spermophiles
- family Scolopacidae
- sandpiper family: sandpipers; woodcocks; snipes; tattlers; curlews; godwits; dowitchers
- family Scolytidae
- large family of bark-boring or wood-boring short-beaked beetles; very destructive to forest and fruit trees
- family Scomberesocidae
- only sauries
- family Scombridae
- marine food fishes: mackerels; chub mackerels; tuna
- family Scorpaenidae
- scorpionfishes; rockfishes; lionfishes
- family Scutigeridae
- a family of Chilopoda
- family Scyliorhinidae
- small bottom-dwelling sharks
- family Sepiidae
- true cuttlefishes
- family Serranidae
- marine fishes: sea basses; sea perches; groupers; jewfish
- family Sialidae
- an arthropod family including: alderflies
- family Sillaginidae
- small family of small food fishes in shallow waters of the Pacific around Indonesia
- family Siluridae
- Old World catfishes
- family Simuliidae
- blackflies and sand flies
- family Sirenidae
- sirens
- family Sisyridae
- an arthropod family of the order Neuroptera that includes spongeflies
- family Sittidae
- nuthatches
- family Soleidae
- soles
- family Solenidae
- razor clams
- family Soricidae
- shrews
- family Spalacidae
- mole rats
- family Sparidae
- porgies; scups
- family Sphecidae
- mud daubers; some digger wasps
- family Spheniscidae
- comprising all existing penguins
- family Sphingidae
- hawkmoths
- family Sphyraenidae
- monotypic family of large active fishes of tropical and subtropical waters: barracuda
- family Sphyrnidae
- hammerhead sharks; bonnethead sharks
- family Spirillaceae
- rigid spirally curved elongate bacteria
- family Spirochaetaceae
- large coarsely spiral bacteria; free-living in fresh or salt water or commensal in bodies of oysters
- family Spirulidae
- coextensive with the genus Spirula; included in the order Belemnoidea in some older classifications
- family Squalidae
- dogfishes having a spine in each dorsal fin
- family Squatinidae
- bottom-dwelling ray-like sharks
- family Squillidae
- crustaceans that burrow in mud or under stones in shallow water along the seashore
- family Staphylinidae
- rove beetles
- family Steatornithidae
- oilbirds
- family Stenopelmatidae
- long-horned grasshoppers
- family Stercorariidae
- jaegers and skuas:
- family Stichaeidae
- pricklebacks
- family Stizidae
- cicada killers
- family Streptomycetaceae
- higher bacteria typically aerobic soil saprophytes
- family Strigidae
- a family of nocturnal birds of the order Strigiformes
- family Stromateidae
- butterfishes: harvest fishes; dollar fishes
- family Strombidae
- the family of conchs
- family Struthionidae
- tall terrestrial birds: ostriches
- family Sturnidae
- Old World starlings
- family Suidae
- pigs; hogs; boars
- family Sulidae
- gannets and boobies
- family Sylviidae
- in some classifications considered a subfamily (Sylviinae) of the family Muscicapidae: Old World (true) warblers; American kinglets and gnatcatchers
- family Syngnathidae
- pipefishes
- family Synodontidae
- soft-finned bottom-dwelling fishes
- family Tabanidae
- horseflies
- family Tachinidae
- parasites on other insects
- family Tachyglossidae
- echidnas
- family Taeniidae
- a family of Cestoda
- family Talpidae
- moles
- family Tapiridae
- tapirs and extinct related forms
- family Tarsiidae
- coextensive with the genus Tarsius: tarsiers
- family Tayassuidae
- peccaries
- family Teiidae
- whiptails; etc.
- family Tenebrionidae
- a family of arthropods including darkling beetles and mealworms
- family Tenrecidae
- tenrecs and extinct related forms
- family Tenthredinidae
- sawflies
- family Terebellidae
- marine burrowing or tube-forming polychete worms usually having long thick bodies
- family Teredinidae
- shipworms
- family Termitidae
- termites
- family Testudinidae
- land tortoises
- family Tetranychidae
- plant-feeding mites
- family Tetraodontidae
- puffers
- family Tetraonidae
- grouse
- family Tettigoniidae
- long-horned grasshoppers; katydids
- family Theraphosidae
- large tropical spiders; tarantulas
- family Theridiidae
- a family of comb-footed spiders
- family Thiobacteriaceae
- free-living coccoid to rod-shaped bacteria that derive energy from oxidizing sulfur or sulfur compounds
- family Thraupidae
- tanagers
- family Threskiornithidae
- ibises
- family Thripidae
- thrips
- family Timaliidae
- babblers
- family Tinamidae
- comprising the tinamous
- family Tineidae
- clothes moths
- family Tingidae
- lace bugs
- family Tipulidae
- crane flies
- family Titanosauridae
- herbivorous dinosaurs of the Cretaceous
- family Todidae
- a family of birds of the order Coraciiformes
- family Torpedinidae
- electric rays
- family Tortricidae
- leaf rollers and codling moths
- family Toxotidae
- archerfishes
- family Trachipteridae
- ribbonfishes
- family Tragulidae
- chevrotains
- family Trephritidae
- fruit flies; some leaf miners
- family Treponemataceae
- small spirochetes some parasitic or pathogenic
- family Triakidae
- small sharks with smooth skins and lacking spines on their dorsal fins
- family Tribonemaceae
- simple filamentous freshwater yellow-green algae
- family Trichechidae
- comprising only the manatees
- family Trichiuridae
- cutlassfishes
- family Trichodontidae
- two species of elongate compressed scaleless large-eyed fishes that live in sand or mud
- family Tridacnidae
- large marine hard-shell clams
- family Triglidae
- in some classifications restricted to the gurnards and subdivided into the subfamilies Triglinae (true sea robins) and Peristediinae (armored sea robins)
- family Trionychidae
- soft-shelled turtles
- family Triopidae
- a family of Notostraca
- family Trochilidae
- hummingbirds
- family Troglodytidae
- wrens
- family Trogonidae
- coextensive with the order Trogoniformes
- family Trombiculidae
- mites
- family Trombidiidae
- mites
- family Tupaiidae
- tree shrews; in some classifications tree shrews are considered prosimian primates
- family Turdidae
- thrushes; in some classifications considered a subfamily (Turdinae) of the family Muscicapidae
- family Turnicidae
- small Old World birds resembling but not related to true quail
- family Tylenchidae
- a family of Nematoda
- family Typhlopidae
- blind snakes
- family Tytonidae
- comprising only the barn owls
- family Uintatheriidae
- an extinct family of Dinocerata
- family Ulvaceae
- thin flat or tubular green algae
- family Unionidae
- freshwater mussels found worldwide
- family Upupidae
- hoopoes
- family Uranoscopidae
- stargazers
- family Ursidae
- bears and extinct related forms
- family Varanidae
- monitor lizards
- family Veneridae
- hard-shell clams
- family Vespertilionidae
- the majority of common bats of temperate regions of the world
- family Vespidae
- an arthropod family of the order Hymenoptera including: yellow jackets; hornets; mason wasps
- family Viperidae
- Old World vipers
- family Vireonidae
- small insectivorous American songbirds
- family Viverrinae
- genets; civets; mongooses
- family Volvocaceae
- unicellular or colonial biflagellate free-swimming flagellates
- family Vombatidae
- wombats
- family Xantusiidae
- night lizards
- family Xenopodidae
- in some classifications the family of the genus Xenopus which is otherwise included in the family Pipidae
- family Xenosauridae
- monotypic family of Mexican lizards
- family Xiphiidae
- comprising the common swordfishes
- family Zapodidae
- jumping mice
- family Zeidae
- a family of fish in the order Zeomorphi
- family Zoarcidae
- eelpouts
- family Zygnemataceae
- pond scums: common freshwater algae forming green slimy masses
- fang
- hollow or grooved tooth of a venomous snake; used to inject its poison
- fang
- canine tooth of a carnivorous animal; used to seize and tear its prey
- fang
- an appendage of insects that is capable of injecting venom; usually evolved from the legs
- farm animal
- any animals kept for use or profit
- Fasciola hepatica
- flatworm parasitic in liver and bile ducts of domestic animals and humans
- Fasciolopsis buski
- fluke that is parasitic on humans and swine; common in eastern Asia
- fawn
- a young deer
- feather
- the light horny waterproof structure forming the external covering of birds
- feeder
- an animal being fattened or suitable for fattening
- feeder
- an animal that feeds on a particular source of food
- feist
- a nervous belligerent little mongrel dog
- felid
- any of various lithe-bodied roundheaded fissiped mammals, many with retractile claws
- Felis bengalensis
- small spotted wildcat of southern Asia and Malaysia
- Felis chaus
- small Asiatic wildcat
- Felis concolor
- large American feline resembling a lion
- Felis domesticus
- any domesticated member of the genus Felis
- Felis ocreata
- widely distributed wildcat of Africa and Asia Minor
- Felis pardalis
- nocturnal wildcat of Central America and South America having a dark-spotted buff-brown coat
- Felis serval
- slender long-legged African wildcat having large untufted ears and tawny black-spotted coat
- Felis silvestris
- bushy-tailed wildcat of Europe that resembles the domestic cat and is regarded as the ancestor of the domestic cat
- Felis tigrina
- medium-sized wildcat of Central America and South America having a dark-striped coat
- Felis wiedi
- small spotted wildcat found from Texas to Brazil
- Felis yagouaroundi
- long-bodied long-tailed tropical American wildcat
- female
- an animal that produces gametes (ova) that can be fertilized by male gametes (spermatozoa)
- female horse
- female equine animal
- female mammal
- animals that nourish their young with milk
- fence lizard
- spiny lizard often seen basking on fences in the United States and northern Mexico
- Fenusa pusilla
- small black sawfly native to Europe but established in eastern United States; larvae mine the leaves of birches causing serious defoliation
- ferret
- domesticated albino variety of the European polecat bred for hunting rats and rabbits
- ferret badger
- small ferret-like badger of southeast Asia
- fetlock
- projection behind and above a horse's hoof
- fetlock
- the joint between the cannon bone and the pastern
- fetter bone
- the part between the fetlock and the hoof
- fetus
- an unborn or unhatched vertebrate in the later stages of development showing the main recognizable features of the mature animal
- fictional animal
- animals that exist only in fiction (usually in children's stories)
- fiddler crab
- burrowing crab of American coastal regions having one claw much enlarged in the male
- field mouse
- any nocturnal Old World mouse of the genus Apodemus inhabiting woods and fields and gardens
- field mouse
- any of various small mouselike rodents of the family Cricetidae (especially of genus Microtus) having a stout short-tailed body and inconspicuous ears and inhabiting fields or meadows
- field spaniel
- large usually black hunting and retrieving spaniel with a dense flat or slightly wavy coat; cross between cocker and Sussex spaniel
- fig-bird
- greenish-yellow Australian oriole feeding chiefly on figs and other fruits
- fighting cock
- a cock bred and trained for fighting
- filaria
- slender threadlike roundworms living in the blood and tissues of vertebrates; transmitted as larvae by biting insects
- filefish
- narrow flattened warm-water fishes with leathery skin and a long file-like dorsal spine
- filly
- a young female horse under the age of four
- Filoviridae
- a family of threadlike RNA viruses that cause diseases in humans and nonhuman primates (monkeys and chimpanzees)
- filovirus
- animal viruses belonging to the family Filoviridae
- fin
- organ of locomotion and balance in fishes and some other aquatic animals
- finch
- any of numerous small songbirds with short stout bills adapted for crushing seeds
- fingerling
- a young or small fish
- finisher
- an animal that wins in a contest of speed
- fire ant
- omnivorous ant of tropical and subtropical America that can inflict a painful sting
- firebug
- a true bug: brightly colored bug that can exude a stain
- firefly
- nocturnal beetle common in warm regions having luminescent abdominal organs
- first stomach
- the first compartment of the stomach of a ruminant; here food is collected and returned to the mouth as cud for chewing
- fish
- any of various mostly cold-blooded aquatic vertebrates usually having scales and breathing through gills
- fish duck
- large crested fish-eating diving duck having a slender hooked bill with serrated edges
- fish family
- any of various families of fish
- fish fly
- similar to but smaller than the dobsonfly; larvae are used as fishing bait
- fish genus
- any of various genus of fish
- fish louse
- a kind of copepod
- fish scale
- scale of the kind that covers the bodies of fish
- fishbone
- a bone of a fish
- fissiped
- terrestrial carnivores; having toes separated to the base: dogs; cats; bears; badgers; raccoons
- Fissipedia
- in some classifications considered a suborder of Carnivora
- Fissurella apertura
- marine limpet having a conical shell with an opening at the apex
- flag
- a conspicuously marked or shaped tail
- flagellate
- a usually nonphotosynthetic free-living protozoan with whiplike appendages; some are pathogens of humans and other animals
- flagellated cell
- any cell or one-celled organism equipped with a flagellum
- flagellum
- a lash-like appendage used for locomotion (e.g., in sperm cells and some bacteria and protozoa)
- flame cell
- organ of excretion in flatworms
- flamingo
- large pink to scarlet web-footed wading bird with down-bent bill; inhabits brackish lakes
- flank
- the side between ribs and hipbone
- flat-coated retriever
- an English breed having a shiny black or liver-colored coat; retrieves game from land or water
- flatfish
- any of several families of fishes having flattened bodies that swim along the sea floor on one side of the body with both eyes on the upper side
- flathead
- food fish of the Indonesian region of the Pacific; resembles gurnards
- flathead
- pallid bottom-dwelling flat-headed fish with large eyes and a duck-like snout
- flatworm
- parasitic or free-living worms having a flattened body
- Flaviviridae
- a family of arboviruses carried by arthropods
- flavivirus
- animal viruses belonging to the family Flaviviridae
- flea
- any wingless bloodsucking parasitic insect noted for ability to leap
- flea beetle
- any small leaf beetle having enlarged hind legs and capable of jumping
- fledgeling
- young bird that has just fledged or become capable of flying
- fleece
- outer coat of especially sheep and yaks
- flicker
- North American woodpecker
- flight feather
- any of the larger wing or tail feathers of a bird
- flightless bird
- flightless birds having flat breastbones lacking a keel for attachment of flight muscles: ostriches; cassowaries; emus; moas; rheas; kiwis; elephant birds
- flipper
- the flat broad limb of aquatic animals specialized for swimming
- Florida smoothhound
- found from the northern Gulf of Mexico to Brazil
- Florida water rat
- of Florida wetlands
- flounder
- any of various European and non-European marine flatfish
- flour beetle
- an insect that infests flour and stored grains
- fluke
- either of the two lobes of the tail of a cetacean
- fluke
- parasitic flatworms having external suckers for attaching to a host
- fly
- two-winged insects characterized by active flight
- flycatching warbler
- any of numerous American wood warblers that feed on insects caught on the wing
- flying fish
- tropical marine fishes having enlarged winglike fins used for brief gliding flight
- flying fox
- large bat with a head that resembles the head of a fox
- flying mouse
- tiny flying phalanger
- flying opossum
- nocturnal phalangers that move with gliding leaps using parachute-like folds of skin along the sides of the body
- flying reptile
- an extinct reptile of the Jurassic and Cretaceous having a bird-like beak and membranous wings supported by the very long fourth digit of each forelimb
- foal
- a young horse
- food fish
- any fish used for food by human beings
- foot
- any of various organs of locomotion or attachment in invertebrates
- foram
- marine microorganism having a calcareous shell with openings where pseudopods protrude
- fore wing
- either of the anterior pair of wings on an insect that has four wings
- forefoot
- a front foot of a quadruped
- foreleg
- the forelimb of a quadruped
- forelimb
- the front limb (or the homologous structure in other animals, such as a flipper or wing)
- forelock
- a lock of a horse's mane that grows forward between the ears
- forepaw
- front paw; analogous to the human hand
- form genus
- an artificial taxonomic category established on the basis of morphological resemblance for organisms of obscure true relationships especially fossil forms
- Formica fusca
- an ant frequently enslaved
- Formica rufa
- reddish-brown European ant typically living in anthills in woodlands
- Formica sanguinea
- slave-making ant widely distributed over the northern hemisphere
- Fossa fossa
- civet of Madagascar
- fossorial foot
- foot adapted for digging as in moles
- fossorial mammal
- a burrowing mammal having limbs adapted for digging
- fox
- alert carnivorous mammal with pointed muzzle and ears and a bushy tail; most are predators that do not hunt in packs
- fox terrier
- small lively black-and-white terriers formerly used to dig out foxes
- foxhound
- medium-sized glossy-coated hounds developed for hunting foxes
- Francisella tularensis
- the type species of the genus Francisella and the causal agent of tularemia in humans; can be used as a bioweapon
- Frankliniella fusca
- injurious to growing tobacco and peanuts
- Fratercula arctica
- common puffin of the northern Atlantic
- Fratercula corniculata
- northern Pacific puffin
- freetail
- small swift insectivorous bat with leathery ears and a long tail; common in warm regions
- French bulldog
- small stocky version of the bulldog having a sleek coat and square head
- freshwater bass
- North American food and game fish
- freshwater clam
- bivalve mollusk abundant in rivers of central United States
- frigate bird
- long-billed warm-water seabird with wide wingspan and forked tail
- Fringilla coelebs
- small European finch with a cheerful song
- Fringilla montifringilla
- Eurasian finch
- fritillary
- butterfly with brownish wings marked with black and silver
- frogfish
- fish having a frog-like mouth with a lure on the snout
- froghopper
- a variety of spittlebug
- frogmouth
- insectivorous bird of Australia and southeastern Asia having a wide frog-like mouth
- fruit bat
- large Old World bat of warm and tropical regions that feeds on fruit
- fruit fly
- any of numerous small insects whose larvae feed on fruits
- fucoid
- a fossilized cast or impression of algae of the order Fucales
- fucoid
- any of various algae of the family Fucaceae
- fucus
- any member of the genus Fucus
- Fucus serratus
- brown algae seaweed with serrated edges
- Fucus vesiculosus
- a common rockweed used in preparing kelp and as manure
- Fulica americana
- a coot found in North America
- Fulmarus glacialis
- heavy short-tailed oceanic bird of polar regions
- Fundulus heteroclitus
- silver-and-black killifish of saltwater marshes along the Atlantic coast of the United States
- Fundulus majalis
- black-barred fish of bays and coastal marshes of the Atlantic and Gulf Coast of the United States
- fungus gnat
- mosquito-like insect whose larvae feed on fungi or decaying vegetation
- fungus gnat
- minute blackish gregarious flies destructive to mushrooms and seedlings
- fur
- dense coat of fine silky hairs on mammals (e.g., cat or seal or weasel)
- fur seal
- eared seal of the southern hemisphere; the thick soft underfur is the source of sealskin
- fur seal
- an eared seal of the northern Pacific
- furcula
- a forked bone formed by the fusion of the clavicles of most birds
- gadfly
- any of various large flies that annoy livestock
- gadoid
- a soft-finned fish of the family Gadidae
- Gadus macrocephalus
- closely related to Atlantic cod
- Gadus morhua
- one of the world's most important commercial fishes
- Galeocerdo cuvieri
- large dangerous warm-water shark with striped or spotted body
- Galeorhinus zyopterus
- Pacific shark valued for its fins (used by Chinese in soup) and liver (rich in vitamin A)
- Galictis vittatus
- carnivore of Central America and South America resembling a weasel with a greyish-white back and dark underparts
- gall gnat
- fragile mosquito-like flies that produce galls on plants
- Gallant Fox
- thoroughbred that won the triple crown in 1930
- Galleria mellonella
- moth whose larvae live in and feed on bee honeycombs
- gallfly
- any of various insects that deposit their eggs in plants causing galls in which the larvae feed
- gallina
- small Asiatic wild bird; believed to be ancestral to domestic fowl
- gallinacean
- heavy-bodied largely ground-feeding domestic or game birds
- Gallinago gallinago
- common snipe of Eurasia and Africa
- Gallinago gallinago delicata
- American snipe
- Gallinago media
- Old World snipe larger and darker than the whole snipe
- Gallinula chloropus
- black gallinule that inhabits ponds and lakes
- Gallinula chloropus cachinnans
- North American dark bluish-grey gallinule
- gallinule
- any of various small aquatic birds of the genus Gallinula distinguished from rails by a frontal shield and a resemblance to domestic hens
- Galloway
- breed of hardy black chiefly beef cattle native to Scotland
- Gallus gallus
- a jungle fowl of southeastern Asia that is considered ancestral to the domestic fowl
- Gallus gallus
- a domestic fowl bred for flesh or eggs; believed to have been developed from the red jungle fowl
- Gambusia affinis
- silvery topminnow with rows of black spots of tropical North America and West Indies; important in mosquito control
- game
- animal hunted for food or sport
- game bird
- any bird (as grouse or pheasant) that is hunted for sport
- game fish
- any fish providing sport for the angler
- game fowl
- any of several breeds reared for cockfighting
- gander
- mature male goose
- gannet
- large heavily built seabird with a long stout bill noted for its plunging dives for fish
- ganoid
- primitive fishes having thick bony scales with a shiny covering
- ganoin
- shiny substance that resemble enamel and is secreted by the corium of certain fishes (especially ganoid fishes) and composes the outer layer of their scales
- garden snail
- any of several inedible snails of the genus Helix; often destructive pests
- garter snake
- any of numerous nonvenomous longitudinally-striped viviparous North American and Central American snakes
- gaskin
- lower part of a horse's thigh between the hock and the stifle
- Gasterophilus intestinalis
- parasitic chiefly on horses
- Gasterosteus
- type genus of the family Gasterosteidae
- Gasterosteus aculeatus
- of rivers and coastal regions
- Gasterosteus pungitius
- confined to rivers
- gastric mill
- thick-walled muscular pouch below the crop in many birds and reptiles for grinding food
- Gastrophryne carolinensis
- small toad of southeastern United States
- Gastrophryne olivacea
- small secretive toad with smooth tough skin of central and western North America
- gastropod
- a class of mollusks typically having a one-piece coiled shell and flattened muscular foot with a head bearing stalked eyes
- gastrula
- double-walled stage of the embryo resulting from invagination of the blastula; the outer layer of cells is the ectoderm and the inner layer differentiates into the mesoderm and endoderm
- Gavialis gangeticus
- large fish-eating Indian crocodilian with a long slender snout
- gaviiform seabird
- seabirds of the order Gaviiformes
- Gazella subgutturosa
- a kind of gazelle
- gazelle
- small swift graceful antelope of Africa and Asia having lustrous eyes
- gecko
- any of various small chiefly tropical and usually nocturnal insectivorous terrestrial lizards typically with immovable eyelids; completely harmless
- gee-gee
- a word for horse used by children or in adult slang
- gelding
- castrated male horse
- Gelechia gossypiella
- small brown moth whose larvae bore into flowers and bolls of cotton
- Gelechia gossypiella
- larvae of a gelechiid moth introduced from Asia; feeds on the seeds of cotton bolls
- gelechiid
- small slender-winged moths whose larvae are agricultural pests
- gempylid
- snake mackerels; elongated marine fishes with oily flesh; resembles mackerels; found worldwide
- Gempylus serpens
- predatory tropical fishes with jutting jaws and strong teeth
- Genetta genetta
- agile Old World viverrine having a spotted coat and long ringed tail
- genus Abramis
- European fishes
- genus Abrocoma
- abrocomes
- genus Abudefduf
- damsel fishes
- genus Acanthisitta
- a genus of Xenicidae
- genus Acanthocybium
- wahoos
- genus Acanthophis
- Australian elapid snakes
- genus Acanthoscelides
- a genus of Bruchidae
- genus Acanthurus
- type genus of the Acanthuridae: doctorfishes
- genus Acarus
- any of several mites of the order Acarina
- genus Accipiter
- type genus of the family Accipitridae
- genus Acherontia
- death's-head moth
- genus Acheta
- common house and field crickets
- genus Achoerodus
- a genus of Labridae
- genus Acinonyx
- cheetahs
- genus Acipenser
- type genus of the Acipenseridae: sturgeons
- genus Acridotheres
- mynas
- genus Acris
- cricket frogs
- genus Acrobates
- a genus of Phalangeridae
- genus Acrocephalus
- a genus of Sylviidae
- genus Acropora
- coelenterate genus of order Madreporaria, including staghorn corals
- genus Actias
- luna moths
- genus Actinia
- a genus of sea anemone common in rock pools
- genus Actinomyces
- type genus of the family Actinomycetaceae
- genus Actitis
- a genus of Scolopacidae
- genus Adalia
- genus of ladybugs
- genus Addax
- genus of antelopes of northern African deserts
- genus Adelges
- type genus of the Adelgidae: plant lice
- genus Adenota
- African antelopes: puku
- genus Aedes
- yellow-fever mosquitos
- genus Aegypius
- a genus of Accipitridae
- genus Aegyptopithecus
- a genus of Hominoidea
- genus Aepyceros
- African antelopes: impalas
- genus Aepyornis
- type genus of the Aepyornidae: elephant birds
- genus Aerobacter
- aerobic bacteria widely distributed in nature
- genus Aetobatus
- a genus of Myliobatidae
- genus Afropavo
- Congo peafowl
- genus Agama
- type genus of the Agamidae
- genus Agapornis
- a genus of Psittacidae
- genus Agelaius
- red-winged blackbirds
- genus Agkistrodon
- copperheads
- genus Agonus
- type genus of the Agonidae
- genus Agriocharis
- a genus of birds of the family Meleagrididae including the ocellated turkey
- genus Agrobacterium
- small motile bacterial rods that can reduce nitrates and cause galls on plant stems
- genus Ailuropoda
- only the giant panda: in some classifications considered a genus of the separate family Ailuropodidae
- genus Ailurus
- lesser pandas
- genus Aix
- wood duck and mandarin duck
- genus Ajaia
- a genus of Platalea
- genus Alauda
- type genus of the Alaudidae: skylarks
- genus Albula
- type and sole genus of the family Albulidae
- genus Alca
- type genus of the Alcidae comprising solely the razorbill
- genus Alcedo
- type genus of the Alcedinidae
- genus Alcelaphus
- African antelopes: hartebeests
- genus Alces
- elk or moose
- genus Alectis
- a genus of Carangidae
- genus Alectoris
- a genus of Perdicidae
- genus Alectura
- brush turkeys
- genus Alepisaurus
- slender scaleless predaceous tropical deep-sea fishes
- genus Aleyrodes
- type genus of the Aleyrodidae
- genus Algeripithecus
- an extinct genus of Hominoidea
- genus Alligator
- type genus of the Alligatoridae
- genus Alopex
- arctic foxes
- genus Alopius
- type genus of the family Alopiidae; in some classifications considered a genus of the family Lamnidae
- genus Alosa
- shad
- genus Alouatta
- howler monkeys
- genus Alsophila
- geometrid moths
- genus Alytes
- midwife toads
- genus Amazona
- a genus of Psittacidae
- genus Ambloplites
- a genus of Centrarchidae
- genus Amblyrhynchus
- marine iguanas
- genus Ambystoma
- type genus of the Ambystomatidae
- genus Ameiurus
- type genus of the Ameiuridae: bullhead catfishes
- genus Amia
- type genus of the Amiidae
- genus Ammodytes
- type genus of the Ammodytidae
- genus Ammotragus
- genus of wild sheep
- genus Amoeba
- protozoan inhabiting moist soils or bottom vegetation in fresh or salt water
- genus Amphibolips
- cynipid gall wasps, especially causing oak-apple galls
- genus Amphioxus
- type genus of the Amphioxidae
- genus Amphiprion
- damsel fishes
- genus Amphisbaenia
- type genus of the Amphisbaenidae
- genus Amphiuma
- congo snakes
- genus Anabas
- the type genus of the family Anabantidae; small fish that resemble perch
- genus Anabrus
- a genus of Tettigoniidae
- genus Anagasta
- moth whose larvae are flour moths
- genus Anarhichas
- type genus of the Anarhichadidae
- genus Anas
- type genus of the Anatidae: freshwater ducks
- genus Anasa
- squash bugs
- genus Anastomus
- openbills
- genus Anatotitan
- genus of large duck-billed dinosaurs; late Cretaceous
- genus Ancylus
- type genus of the family Ancylidae: river limpet
- genus Andrena
- a solitary burrowing short-tongued bee
- genus Andricus
- cynipid gall wasps, chiefly affecting oaks
- genus Aneides
- climbing salamanders
- genus Anguilla
- type genus of the Anguillidae: eels
- genus Anguillula
- a genus of Cephalobidae
- genus Anguis
- type genus of the Anguidae: blindworms
- genus Anhima
- type genus of the Anhimidae; horned screamers
- genus Anhinga
- type genus of the Anhingidae
- genus Anisotremus
- a genus of Haemulidae
- genus Ankylosaurus
- armored herbivorous dinosaurs of the Cretaceous
- genus Anoa
- a genus of mammals of the family Bovidae
- genus Anodonta
- thin-shelled freshwater mussels
- genus Anolis
- New World chameleons
- genus Anomala
- genus of beetles whose grubs feed mainly on roots of plants; includes several pests of cultivated grasses
- genus Anomalops
- type genus of the family Anomalopidae
- genus Anomalopteryx
- small moas
- genus Anomia
- type genus of the family Anomiidae: saddle oysters
- genus Anopheles
- malaria mosquitoes; distinguished by the adult's head-downward stance and absence of breathing tubes in the larvae
- genus Anser
- typical geese
- genus Antedon
- a genus of echinoderms of the family Antedonidae
- genus Antheraea
- large moths whose larvae produce silk of high quality
- genus Anthidium
- potter bees
- genus Anthonomus
- weevils destructive of cultivated plants
- genus Anthus
- pipits
- genus Antidorcas
- springboks
- genus Antigonia
- a genus of fish in the family Caproidae
- genus Antilocapra
- type and sole genus of the Antilocapridae comprising one species
- genus Antilope
- blackbucks
- genus Antrodemus
- carnivorous dinosaur of North America; late Jurassic
- genus Antrozous
- a genus of Vespertilionidae
- genus Aotus
- douroucoulis
- genus Apatura
- large Old World butterflies
- genus Aphis
- type genus of the Aphididae: injurious to fruit trees and vegetables
- genus Aphriza
- a genus of Scolopacidae
- genus Aphrophora
- a genus of Cercopidae
- genus Apis
- type genus of the Apidae: honeybees
- genus Aplodontia
- type genus of the Aplodontiidae: comprising the mountain beavers
- genus Aplysia
- type genus of the family Aplysiidae
- genus Apodemus
- Old World field mice
- genus Apogon
- type genus of the Apogonidae
- genus Appendicularia
- a genus of chordates in the class Larvacea
- genus Aptenodytes
- large penguins
- genus Apteryx
- type genus of the Apterygidae: kiwis
- genus Apus
- type genus
- genus Aquila
- a genus of Accipitridae
- genus Ara
- macaws
- genus Aramus
- genus of large brown long-billed wading birds found in warm swampy regions of the western hemisphere: courlan; limpkin
- genus Araneus
- a genus of orb-weaving spiders including common garden spiders and barn spiders
- genus Arca
- type genus of the family Arcidae: ark shells and blood clams
- genus Arcella
- type genus of the Arcellidae
- genus Archaeopteryx
- a genus of fossil birds
- genus Archaeornis
- a genus of fossil bird
- genus Archidiskidon
- a genus of Elephantidae
- genus Archilochus
- a genus of Trochilidae
- genus Architeuthis
- giant squid
- genus Archosargus
- a genus of Sparidae
- genus Arctictis
- binturongs
- genus Arctocebus
- a genus of Lorisidae
- genus Arctocephalus
- fur seals
- genus Arctonyx
- a genus of Mustelidae
- genus Ardea
- type genus of the Ardeidae: large New and Old World herons
- genus Arenaria
- turnstones
- genus Argentina
- type genus of the Argentinidae: argentines
- genus Argentinosaurus
- enormous dinosaur of the middle Cretaceous found in Argentina
- genus Argiope
- the type genus of Argiopidae; small genus of orb-weaving spiders
- genus Argonauta
- type genus of the family Argonautidae: paper nautilus
- genus Argusianus
- argus pheasants
- genus Argynnis
- fritillaries
- genus Argyrotaenia
- orange tortrix
- genus Arilus
- a genus of Reduviidae
- genus Ariomma
- a genus of Stromateidae
- genus Arius
- type genus of the Ariidae: sea catfishes
- genus Arizona
- glossy snake
- genus Armadillidium
- type genus of the Armadillidiidae
- genus Artamus
- type genus of the Artamidae
- genus Arvicola
- in some classifications considered synonymous with Microtus
- genus Ascaphus
- type genus of the Ascaphidae; in some classifications included in the family Leiopelmatidae
- genus Ascaridia
- roundworm having a preanal sucker
- genus Ascaris
- type genus of the family Ascaridae: roundworms with a three-lipped mouth
- genus Ascophyllum
- brown algae distinguished by compressed or inflated branchlets along the axis
- genus Asio
- a genus of European owls
- genus Aspidelaps
- African coral snakes
- genus Aspidiotus
- a genus of Diaspididae
- genus Aspidophoroides
- alligatorfishes
- genus Astacus
- type genus of the family Astacidae; Old World crayfish
- genus Astrophyton
- includes many of the basket stars
- genus Astropogon
- a genus of fish of the family Apogonidae
- genus Ateles
- spider monkeys
- genus Athene
- a genus of Strigidae
- genus Atherinopsis
- a genus of Atherinidae
- genus Atherurus
- a genus of Hystricidae
- genus Atrichornis
- type genus of the Atrichornithidae
- genus Atticus
- atlas moth
- genus Aulacorhyncus
- a genus of Ramphastidae
- genus Aulostomus
- type genus of the Aulostomidae
- genus Auriparus
- a genus of Paridae
- genus Australopithecus
- extinct genus of African hominid
- genus Automeris
- io moth
- genus Avahi
- a genus of Indriidae
- genus Aythya
- canvasback; redhead; pochard; etc.
- genus Babyrousa
- a genus of Suidae
- genus Bacillus
- type genus of the Bacillaceae; includes many saprophytes important in decay of organic matter and a number of parasites
- genus Bacteroides
- type genus of Bacteroidaceae; genus of Gram-negative rodlike anaerobic bacteria producing no endospores and no pigment and living in the gut of man and animals
- genus Baiomys
- pygmy mice
- genus Bairdiella
- drumfish
- genus Balaena
- type genus of the Balaenidae: Greenland whales
- genus Balaeniceps
- type genus of the Balaenicipitidae: shoebills
- genus Balaenoptera
- type genus of the Balaenopteridae
- genus Balanus
- type genus of the family Balanidae
- genus Balistes
- type genus of the Balistidae
- genus Bankia
- giant shipworms
- genus Barosaurus
- huge quadrupedal herbivorous dinosaur; late Jurassic
- genus Bartramia
- a genus of Scolopacidae
- genus Basiliscus
- a reptile genus of Iguanidae
- genus Bassariscus
- cacomistles
- genus Bathyergus
- mole rats
- genus Batrachoseps
- slender salamanders
- genus Bemisia
- sweet-potato whitefly
- genus Beroe
- coextensive with the class Nuda
- genus Bettongia
- jerboa kangaroo
- genus Bibos
- wild ox
- genus Bison
- sometimes considered a subgenus of genus Bos: American buffalo
- genus Bitis
- a genus of Viperidae
- genus Blaberus
- giant cockroaches
- genus Blarina
- shrews
- genus Blatta
- type genus of the Blattidae: cockroaches infesting buildings worldwide
- genus Blattella
- small cockroaches
- genus Blennius
- type genus of the Blenniidae
- genus Blissus
- chinch bugs
- genus Bombina
- fire-bellied toads
- genus Bombus
- bumblebees
- genus Bombyx
- type genus of the Bombycidae: Chinese silkworm moth
- genus Bonasa
- ruffed grouse
- genus Borrelia
- small flexible parasitic spirochetes having three to five wavy spirals
- genus Bos
- wild and domestic cattle; in some classifications placed in the subfamily Bovinae or tribe Bovini
- genus Boselaphus
- Indian antelopes: nilgais
- genus Botaurus
- bitterns
- genus Bothrops
- fer-de-lance
- genus Brachinus
- bombardier beetles
- genus Bradypus
- type genus of the Bradypodidae: three-toed sloths
- genus Brama
- type genus of the Bramidae
- genus Branchiobdella
- type genus of the Branchiobdellidae: a small worm that lives on the gills or surface of a crayfish attached by a sucker
- genus Branta
- wild geese
- genus Brevoortia
- menhaden
- genus Brontosaurus
- large quadrupedal herbivorous dinosaurs with very long neck and tail; late Jurassic
- genus Browmius
- cusk
- genus Bruchus
- type genus of the Bruchidae
- genus Bubalus
- in some classification systems included in genus Bos; water buffaloes
- genus Bubo
- a genus of Strigidae
- genus Bubulcus
- small white egrets
- genus Bucephala
- buffleheads and goldeneyes
- genus Buceros
- type genus of the family Bucerotidae
- genus Budorcas
- gnu goats
- genus Bufo
- type genus of the Bufonidae; common toads of New and Old Worlds
- genus Bungarus
- kraits
- genus Burhinus
- type genus of the Burhinidae: stone curlews
- genus Burmeisteria
- a genus of Dasypodidae
- genus Buteo
- broad-winged soaring hawks
- genus Cabassous
- solely the tatouay
- genus Cacajao
- uakaris
- genus Cacatua
- a genus of Psittacidae
- genus Cacicus
- a genus of tropical American orioles
- genus Cadra
- a genus of Pyralidae
- genus Caenolestes
- type genus of the family Caenolestidae
- genus Caiman
- caimans
- genus Cairina
- a genus of Anatidae
- genus Calamus
- a genus of Sparidae
- genus Calidris
- a genus of Scolopacidae
- genus Callicebus
- titis
- genus Callimorpha
- cinnabar moths
- genus Callinectes
- New World blue crabs
- genus Calliophis
- Asian coral snakes
- genus Calliphora
- type genus of the Calliphoridae: blowflies
- genus Callisaurus
- zebra-tailed lizard
- genus Callithrix
- type genus of the Callithricidae: true marmosets
- genus Callorhinus
- fur seals
- genus Calosoma
- genus of large predaceous ground beetles that feed on injurious caterpillars
- genus Calymmatobacterium
- a genus of bacterial rods containing only the one species that causes granuloma inguinale
- genus Cambarus
- a genus of Astacidae
- genus Camelus
- type genus of the Camelidae: camels
- genus Campephilus
- a genus of Picidae
- genus Camponotus
- carpenter ants
- genus Campylorhynchus
- alternative classifications for the cactus wrens
- genus Canachites
- spruce grouse
- genus Cancer
- type genus of the family Cancridae
- genus Canis
- type genus of the Canidae: domestic and wild dogs; wolves; jackals
- genus Capra
- goats
- genus Caprella
- skeleton shrimp
- genus Capreolus
- roe deer
- genus Capricornis
- serows
- genus Caprimulgus
- type genus of the Caprimulgidae
- genus Capros
- a genus of fish in the family Caproidae
- genus Caranx
- type genus of the Carangidae
- genus Carassius
- goldfish
- genus Carcharhinus
- type genus of the Carcharhinidae
- genus Carcharias
- type and sole genus of Carchariidae: sand sharks
- genus Carcharodon
- man-eating sharks
- genus Cardium
- type genus of the family Cardiidae: cockles
- genus Carduelis
- in some classifications considered the type genus of a subfamily Carduelinae of the family Fringillidae: goldfinches; siskins; redpolls; linnets
- genus Caretta
- loggerhead turtles
- genus Cariama
- the type genus of the Cariamidae comprising only the crested cariama
- genus Carphophis
- thunder snake
- genus Carpocapsa
- codling moths
- genus Carpodacus
- house finches and purple finches
- genus Casmerodius
- a white egrets
- genus Castor
- type genus of the Castoridae: beavers
- genus Castoroides
- extinct beavers of the Pleistocene; of eastern and southern United States
- genus Casuarius
- type and sole genus of the Casuaridae: cassowaries
- genus Catacala
- moths whose larvae are cutworms: underwings
- genus Catharacta
- skuas
- genus Cathartes
- type genus of the Cathartidae: turkey vultures
- genus Catoptrophorus
- willet
- genus Catostomus
- type genus of the family Catostomidae
- genus Cavia
- type genus of the Caviidae: guinea pigs
- genus Cebuella
- pygmy marmosets
- genus Cebus
- type genus of the Cebidae
- genus Centrocercus
- sage grouse
- genus Centropomus
- type genus of the Centropomidae: snooks
- genus Centropristis
- sea basses
- genus Centropus
- a genus of Cuculidae
- genus Cephalopterus
- a genus of Cotingidae
- genus Cepphus
- a genus of birds including: guillemots
- genus Cerapteryx
- antler moths
- genus Cerastes
- horned vipers
- genus Ceratitis
- Mediterranean fruit flies
- genus Ceratodus
- type genus of the Ceratodontidae: extinct genus of lungfishes
- genus Ceratopogon
- type genus of the Ceratopogonidae
- genus Ceratosaurus
- primitive saurischian carnivorous dinosaurs
- genus Ceratotherium
- African genus
- genus Cercocebus
- mangabeys
- genus Cercopithecus
- type genus of the Cercopithecidae: guenons
- genus Certhia
- type genus of the Certhiidae
- genus Cervus
- the type genus of the Cervidae
- genus Ceryle
- a genus of birds of the family Alcedinidae
- genus Cestum
- Venus's girdle
- genus Cetonia
- a genus of Cetoniidae
- genus Cetorhinus
- comprising only the basking sharks; in some classifications considered the type genus of a separate family Cetorhinidae
- genus Chaenopsis
- a genus of fish of the family Clinidae including pikeblennies
- genus Chaetodipterus
- a genus of Ephippidae
- genus Chaetodon
- type genus of the Chaetodontidae
- genus Chalcis
- type genus of the Chalcididae
- genus Chalcostigma
- thornbills
- genus Chamaea
- a genus of Paridae
- genus Chamaeleon
- type genus of the Chamaeleontidae
- genus Chara
- green algae common in freshwater lakes of limestone districts
- genus Charadrius
- type genus of the Charadriidae: plovers
- genus Charina
- boas of western North America
- genus Charronia
- a genus of Mustelidae
- genus Chateura
- a genus of Apodidae
- genus Chauna
- crested screamers
- genus Chelifer
- a genus of Chelonethida
- genus Chelonia
- green turtles
- genus Chelydra
- snapping turtles
- genus Chilomastix
- flagellates parasitic in intestines of vertebrates including humans
- genus Chilomeniscus
- sand snakes
- genus Chilomycterus
- burrfishes
- genus Chimaera
- type genus of the Chimaeridae
- genus Chinchilla
- type genus of the Chinchillidae
- genus Chirocephalus
- fairy shrimp; brine shrimp
- genus Chironomus
- type genus of the Chironomidae
- genus Chiton
- a genus of Polyplacophora
- genus Chlamydera
- a genus of Ptilonorhynchidae
- genus Chlamydia
- type genus of the family Chlamydiaceae: disease-causing parasites
- genus Chlamydomonas
- type genus of the Chlamydomonadaceae; solitary doubly-flagellated plant-like algae common in fresh water and damp soil; multiply freely; often a pest around filtration plants
- genus Chlamydosaurus
- frilled lizards
- genus Chlamyphorus
- pichiciago
- genus Chlorella
- nonmotile unicellular green algae potentially important as source of high-grade protein and B-complex vitamins
- genus Chlorococcum
- type genus of Chlorococcales; unicellular green algae occurring singly or in a layer on soil or damp rock
- genus Chlorophis
- African green snakes
- genus Chlorophoneus
- a genus of Malaconotinae
- genus Chlorura
- towhees
- genus Choeronycteris
- a genus of Phyllostomatidae
- genus Choloepus
- a genus of Megalonychidae consisting of the two-toed sloth
- genus Chondrus
- a genus of protoctist
- genus Chordeiles
- a genus of Caprimulgidae
- genus Choriotis
- Australian bustard
- genus Chorizagrotis
- moths whose larvae are army cutworms
- genus Chronoperates
- a reptile genus of Therapsida
- genus Chrysaora
- a genus of Scyphozoa
- genus Chrysemys
- painted turtles
- genus Chrysochloris
- type genus of the Chrysochloridae
- genus Chrysolophus
- golden pheasants
- genus Chrysophrys
- Australian snapper
- genus Chunga
- a genus of Cariamidae
- genus Cicada
- type genus of the Cicadidae: cicadas
- genus Ciconia
- type genus of the Ciconiidae: European storks
- genus Cimex
- type genus of the Cimicidae: bedbugs
- genus Cinclus
- type genus of the family Cinclidae
- genus Circaetus
- harrier eagles
- genus Circus
- a genus of haws comprising the harriers
- genus Cistothorus
- marsh wrens
- genus Citharichthys
- a genus of Bothidae
- genus Cladorhyncus
- one of two genera of stilts; similar to avocets but with straight bills
- genus Clangula
- a genus of ducks
- genus Clethrionomys
- a genus of Cricetidae
- genus Clostridium
- anaerobic or micro-aerophilic rod-shaped or spindle-shaped saprophytes; nearly cosmopolitan in soil, animal intestines, and dung
- genus Clupea
- type genus of the Clupeidae: typical herrings
- genus Cnemidophorus
- whiptails
- genus Coccothraustes
- large finches
- genus Coccus
- type genus of the Coccidae
- genus Coccyzus
- a genus of Cuculidae
- genus Cochlearius
- boatbills
- genus Coelophysis
- late Triassic carnivorous saurischian dinosaurs
- genus Coereba
- type genus of the Coerebidae
- genus Colaptes
- a genus of Picidae
- genus Coleonyx
- banded geckos
- genus Colinus
- New World quail: the bobwhites
- genus Collocalia
- a genus of Apodidae
- genus Colobus
- a genus of Cercopithecidae
- genus Coluber
- racers
- genus Columba
- type genus of the Columbidae: typical pigeons
- genus Comatula
- former usage synonymous with Antedon
- genus Compsognathus
- a reptile genus of Theropoda
- genus Condylura
- star-nosed moles
- genus Conepatus
- a genus of Mustelidae
- genus Conilurus
- jerboa rats
- genus Connochaetes
- African antelopes: gnus
- genus Contopus
- pewees
- genus Conuropsis
- a genus of Psittacidae
- genus Coracias
- type genus of the Coraciidae
- genus Coragyps
- a genus of Cathartidae
- genus Cordylus
- type genus of the Cordylidae; spiny lizards somewhat resembling tiny crocodiles
- genus Coregonus
- type genus of the Coregonidae: whitefishes
- genus Corixa
- type genus of the Corixidae: boat bugs
- genus Corvus
- type genus of the Corvidae: crows and ravens
- genus Corydalis
- type genus of the Corydalidae
- genus Corynebacterium
- the type genus of the family Corynebacteriaceae which is widely distributed in nature; the best known are parasites and pathogens of humans and domestic animals
- genus Corythosaurus
- genus of duck-billed dinosaurs of late Cretaceous
- genus Coscoroba
- a genus of Anatidae
- genus Cosmocampus
- a genus of fish in the family Syngnathidae
- genus Costia
- a genus of flagellate protoctist
- genus Cotinga
- type genus of the Cotingidae: cotingas
- genus Cottus
- type genus of the Cottidae: sculpins
- genus Coturnix
- Old World quail
- genus Cracticus
- type genus of the Cracticidae: Australian butcherbirds
- genus Crangon
- type genus of the family Crangonidae
- genus Crassostrea
- Virginia oysters
- genus Crax
- type genus of the Cracidae: curassows
- genus Crex
- corncrakes
- genus Cricetus
- type genus of the Cricetidae: Old World hamsters
- genus Crocethia
- a genus of Scolopacidae
- genus Crocodilus
- type genus of the Crocodylidae
- genus Crocuta
- a genus of Hyaenidae
- genus Crotalus
- large rattlesnakes; seldom bite unless startled or pursuing prey
- genus Crotaphytus
- collared lizards
- genus Crotophaga
- ani
- genus Cryptacanthodes
- a genus of Stichaeidae
- genus Cryptobranchus
- type genus of the Cryptobranchidae
- genus Cryptocercus
- cockroaches
- genus Cryptoprocta
- large primitive cat-like carnivores inhabiting forests of Madagascar
- genus Cryptotermes
- genus of dry wood termites; cosmopolitan in distribution; sometimes considered a subgenus of Kalotermes
- genus Cryptotis
- least shrews
- genus Ctenocephalides
- an arthropod genus of fleas
- genus Ctenocephalus
- a former usage synonymous with Ctenocephalides
- genus Cuculus
- type genus of the Cuculidae
- genus Culex
- type genus of the Culicidae: widespread genus of mosquitoes distinguished by holding the body parallel to the resting surface
- genus Cuniculus
- pacas
- genus Cuon
- Asiatic wild dog
- genus Cursorius
- coursers
- genus Cuterebra
- type genus of the Cuterebridae
- genus Cyamus
- whale lice
- genus Cyanocitta
- New World jays
- genus Cyclopes
- only the silky anteater
- genus Cyclops
- copepod water fleas
- genus Cyclopterus
- type genus of the Cyclopteridae: lumpfishes
- genus Cygnus
- a genus of Anatidae
- genus Cynips
- type genus of the Cynipidae: gall wasps
- genus Cynocephalus
- type genus of the family Cynocephalidae
- genus Cynomys
- prairie dogs
- genus Cynopterus
- a genus of Megachiroptera
- genus Cynoscion
- sea trout
- genus Cypraea
- type genus of the family Cypraeidae: the typical cowries
- genus Cyprinus
- type genus of the family Cyprinidae: carp
- genus Cystophora
- hooded seals
- genus Dacelo
- Australasian kingfishers
- genus Dactylopius
- type genus of the Dactylopiidae
- genus Dactylopterus
- a genus of Dactylopteridae
- genus Dama
- fallow deer
- genus Damaliscus
- African antelopes: sassabies
- genus Danaus
- type genus of the Danaidae: monarch butterflies
- genus Daphnia
- water fleas
- genus Dasyatis
- type genus of the Dasyatidae
- genus Dasyprocta
- type genus of the Dasyproctidae: agoutis
- genus Dasypus
- type genus of the Dasypodidae
- genus Dasyurus
- type genus of the family Dasyuridae: native cats
- genus Daubentonia
- type genus; coextensive with the family Daubentoniidae
- genus Decapterus
- scads especially mackerel scad; cosmopolitan in distribution
- genus Deinocheirus
- a reptile genus of Ornithomimida
- genus Deinonychus
- advanced bipedal carnivorous dinosaur
- genus Delichon
- a genus of Hirundinidae
- genus Delphinapterus
- white whale
- genus Delphinus
- type genus of the Delphinidae
- genus Dendroaspis
- mambas
- genus Dendrocolaptes
- type genus of the Dendrocolaptidae
- genus Dendroctonus
- genus of small bark beetles destructive especially to mature conifers
- genus Dendroica
- a genus of Parulidae
- genus Dendrolagus
- tree wallabies
- genus Denisonia
- copperheads
- genus Dermacentor
- vectors of important diseases of man and animals
- genus Dermatobia
- larvae live under the skin of domestic mammals and humans
- genus Dermochelys
- type genus of the Dermochelyidae: leatherback turtles
- genus Desmidium
- a genus of protoctist
- genus Desmodus
- type genus of the Desmodontidae: vampire bats
- genus Desmograthus
- an amphibian genus of Plethodontidae
- genus Diadophis
- a genus of reptiles of the family Colubridae including ringneck snakes
- genus Dialeurodes
- a genus of Aleyrodidae
- genus Diapheromera
- a genus of Phasmidae
- genus Dicamptodon
- type genus of the Dicamptodontidae
- genus Diceros
- most common species in Africa
- genus Dicrostonyx
- pied lemmings
- genus Didelphis
- type genus of the family Didelphidae
- genus Difflugia
- genus of protozoans related to ameba
- genus Dimetrodon
- a reptile genus of Pelycosauria
- genus Dinornis
- type genus of the Dinornithidae: large moas
- genus Diodon
- type genus of the Diodontidae
- genus Diomedea
- type of the Diomedeidae
- genus Diphylla
- vampire bats
- genus Diplococcus
- a genus of bacteria
- genus Diplodocus
- a reptile genus of the suborder Sauropoda
- genus Dipodomys
- kangaroo rats
- genus Dipsosaurus
- desert iguanas
- genus Dipus
- type genus of the Dipodidae; typical jerboas having three toes on each hind foot
- genus Dolichonyx
- bobolinks
- genus Dolichotis
- maras
- genus Doliolum
- type genus of the Doliolidae
- genus Draco
- a reptile genus known as flying dragons or flying lizards
- genus Dracunculus
- type genus of the family Dracunculidae
- genus Dreissena
- zebra mussels
- genus Drepanis
- a genus of Drepanididae
- genus Dromaius
- a genus of birds in the order Casuariiformes
- genus Drosophila
- a genus of Drosophilidae
- genus Drymarchon
- a genus of Colubridae
- genus Dryopithecus
- genus of Old World hominoids; Miocene and Pliocene
- genus Dugong
- type genus of the Dugongidae comprising only the dugongs
- genus Dumetella
- catbirds
- genus Dusicyon
- crab-eating dog
- genus Dysdercus
- a genus of slender long-legged bugs that feed on the developing seeds of cotton and stain it
- genus Eacles
- imperial moths
- genus Echeneis
- type genus of the Echeneididae: typical remoras
- genus Echidnophaga
- a genus of Siphonaptera
- genus Echinococcus
- tapeworms
- genus Ectopistes
- a genus of Columbidae
- genus Edaphosaurus
- type genus of the Edaphosauridae
- genus Edmontosaurus
- duck-billed dinosaurs of Canada
- genus Egretta
- small Old and New World herons
- genus Eimeria
- type genus of the family Eimeriidae; includes serious pathogens
- genus Eira
- a genus of Mustelidae
- genus Elagatis
- a genus of Carangidae
- genus Elanoides
- a genus of kites
- genus Elanus
- a genus of small kites of both Old and New Worlds
- genus Elaphe
- North American rat snakes
- genus Elaphurus
- a genus of Cervidae
- genus Electrophorus
- type genus of the family Electrophoridae; electric eels
- genus Elephas
- type genus of the family Elephantidae
- genus Eleutherodactylus
- completely terrestrial robber frogs
- genus Eliomys
- lerots
- genus Elops
- type genus of the Elopidae: tenpounder
- genus Emberiza
- Old World buntings
- genus Endamoeba
- the type genus of the family Endamoebidae
- genus Engraulis
- type genus of the family Engraulidae
- genus Enhydra
- sea otters
- genus Ensis
- razor clams
- genus Enterobius
- pinworms
- genus Eoraptor
- primitive theropod found in Argentina; early Triassic
- genus Ephestia
- small moths whose larvae spin silken tunnels and feed on stored food products
- genus Ephippiorhynchus
- saddlebills
- genus Epilachna
- genus of ladybugs native to Mexico and Central America; both larvae and adults feed on plants
- genus Epinephelus
- genus of groupers or sea bass
- genus Eptatretus
- a genus of fossil fish of the family Myxinidae
- genus Eptesicus
- a genus of Vespertilionidae
- genus Equetus
- drumfish
- genus Equus
- type genus of the Equidae: only surviving genus of the family Equidae
- genus Erethizon
- a genus of Erethizontidae
- genus Eretmochelys
- hawksbills
- genus Erignathus
- bearded seals
- genus Erinaceus
- type genus of the family Erinaceidae: hedgehogs
- genus Eriosoma
- woolly aphids
- genus Erithacus
- Old World thrushes
- genus Erolia
- a genus of Scolopacidae
- genus Erwinia
- a genus of bacteria
- genus Erythrocebus
- patas
- genus Escherichia
- a genus of bacteria
- genus Eschrichtius
- type and sole genus of the Eschrichtiidae
- genus Esox
- type and only genus of the family Esocidae
- genus Estrilda
- avadavats
- genus Etropus
- a genus of Bothidae
- genus Euarctos
- American black bears; in some classifications not a separate genus from Ursus
- genus Eucinostomus
- a genus of Gerreidae
- genus Euderma
- a genus of Vespertilionidae
- genus Eudyptes
- rock hoppers
- genus Euglena
- type genus of the family Euglenaceae: green algae with a single flagellum
- genus Eumeces
- New World skinks
- genus Eumenes
- mason wasps
- genus Eumetopias
- sea lions
- genus Eumops
- mastiff bats
- genus Eunectes
- anacondas
- genus Euphagus
- a genus of Icteridae
- genus Euphractus
- a genus of Dasypodidae
- genus Euplectella
- a genus of Hyalospongiae
- genus Euproctis
- a genus of Lymantriidae
- genus Euryale
- basket stars
- genus Eutamias
- chipmunks of western America and Asia
- genus Euthynnus
- a genus of Scombridae
- genus Exaeretodon
- a genus of reptiles of the division Cynodontia
- genus Falco
- a genus of Falconidae
- genus Fasciola
- a genus of Fasciolidae
- genus Fasciolopsis
- a genus of Fasciolidae
- genus Felis
- type genus of the Felidae: true cats and most wildcats
- genus Fissurella
- type genus of the family Fissurellidae: keyhole limpets
- genus Fistularia
- type genus of the family Fistulariidae
- genus Forficula
- type genus of Forficulidae
- genus Formica
- type genus of the Formicidae
- genus Formicarius
- type genus of the Formicariidae
- genus Fossa
- monotypic genus of Madagascar civets closely related to palm civets
- genus Francisella
- a genus of Gram-negative aerobic bacteria that occur as pathogens and parasite in many animals (including humans)
- genus Frankliniella
- tobacco thrips
- genus Fratercula
- puffins
- genus Fregata
- type genus of the Fregatidae
- genus Fringilla
- type genus of the Fringillidae: chaffinch, brambling
- genus Fucus
- type genus of the family Fucaceae: cartilaginous brown algae
- genus Fulica
- coots
- genus Fulmarus
- fulmars
- genus Fundulus
- killifish
- genus Fungia
- a genus comprising the usual mushroom corals
- genus Furnarius
- type genus of the family Furnariidae: ovenbirds
- genus Gadus
- type genus of the Gadidae: the typical codfishes
- genus Galago
- bush babies
- genus Galeocerdo
- tiger sharks
- genus Galeorhinus
- a genus of Carcharhinidae
- genus Galictis
- alternative name for the genus Grison
- genus Galleria
- a genus of Pyralidae
- genus Gallinago
- snipes
- genus Gallinula
- gallinules
- genus Gallirallus
- rails of New Zealand
- genus Gallus
- common domestic birds and related forms
- genus Gambelia
- leopard lizards
- genus Gambusia
- mosquitofish
- genus Garrulus
- type genus of the Garrulinae: Old World jays
- genus Gasterophilus
- type genus of the Gasterophilidae: horse botflies
- genus Gastrophryne
- primarily tropical narrow-mouthed toads
- genus Gavia
- type genus of the Gavidae: loons
- genus Gavialis
- type genus of the Gavialidae
- genus Gazella
- typical gazelles
- genus Gelechia
- type genus of the Gelechiidae: pink bollworms
- genus Gempylus
- type genus of the Gempylidae
- genus Genetta
- genets
- genus Genyonemus
- a genus of Sciaenidae
- genus Geochelone
- giant tortoises
- genus Geococcyx
- roadrunners
- genus Geomys
- type genus of the Geomyidae
- genus Geophilus
- type genus of the Geophilidae: a cosmopolitan genus of centipedes sometimes called earwigs
- genus Geothlypis
- yellowthroats
- genus Gerbillus
- type genus of the Gerbillinae: typical gerbils
- genus Gerres
- type genus of the Gerreidae
- genus Gerrhonotus
- alligator lizards
- genus Gerris
- type genus of the Gerrididae
- genus Giardia
- flagellates parasitic in intestines of vertebrates
- genus Ginglymostoma
- nurse sharks
- genus Giraffa
- type genus of the Giraffidae
- genus Glareola
- type genus of the Glareolidae: the pratincoles
- genus Glaucomys
- New World flying squirrels
- genus Glis
- type genus of the Gliridae
- genus Globicephala
- pilot whales
- genus Globigerina
- type genus of the family Globigerinidae
- genus Glossina
- type genus of the Glossinidae: tsetse flies
- genus Glossopsitta
- a genus of Loriinae
- genus Gobiesox
- type genus of the Gobiesocidae
- genus Gobio
- true gudgeons
- genus Gomphotherium
- type genus of the Gomphotheriidae
- genus Gonorhynchus
- slender cylindrical marine fishes lacking air bladders and teeth
- genus Gopherus
- gopher tortoises
- genus Gorgonocephalus
- basket stars
- genus Gorilla
- gorillas
- genus Gracula
- mynas
- genus Grampus
- grampus
- genus Grison
- a genus of Mustelidae
- genus Grus
- type genus of the Gruidae: typical cranes
- genus Gulo
- a genus of Mustelidae
- genus Gymnelis
- a genus of Zoarcidae
- genus Gymnogyps
- containing solely the California condor
- genus Gymnorhina
- in some classifications placed in the family Laniidae: Australian piping crows
- genus Gymnura
- butterfly rays
- genus Gypaetus
- in some classifications the type genus of the family Aegypiidae
- genus Gyps
- a genus of Accipitridae
- genus Haematobia
- European genus of bloodsucking flies
- genus Haematopus
- oystercatchers
- genus Haemopis
- leeches
- genus Haemoproteus
- type genus of the family Haemoproteidae
- genus Haemulon
- type genus of the Haemulidae
- genus Halcyon
- a large kingfisher widely distributed in warmer parts of the Old World
- genus Haldea
- ground snakes
- genus Haliaeetus
- a genus of Accipitridae
- genus Halicoeres
- a genus of Labridae
- genus Haliotis
- type genus of the family Haliotidae
- genus Haminoea
- common genus of marine bubble shells of the Pacific coast of North America
- genus Harpia
- a genus of Accipitridae
- genus Heliobacter
- a genus of helical or curved or straight aerobic bacteria with rounded ends and multiple flagella; found in the gastric mucosa of primates (including humans)
- genus Heliothis
- a genus of Noctuidae
- genus Helix
- type genus of the family Helicidae
- genus Heloderma
- type genus of the Helodermatidae; American venomous lizards
- genus Hemachatus
- ringhals
- genus Hemigalus
- banded palm civets
- genus Hemigrammus
- tetras
- genus Hemipteronatus
- razor fish
- genus Hemitripterus
- sea ravens
- genus Hermissenda
- genus of marine sea slugs
- genus Herpestes
- mongooses
- genus Herrerasaurus
- primitive theropod found in Argentina; early Triassic
- genus Hesperiphona
- evening grosbeak
- genus Heterocephalus
- sand rats
- genus Heterodon
- a genus of small colubrid snakes containing the North American hognose snakes
- genus Heteroscelus
- tattlers
- genus Hexagrammos
- type genus of the Hexagrammidae
- genus Hexamita
- flagellates free-living or parasitic in intestines of birds
- genus Hexanchus
- a genus of Hexanchidae
- genus Himantopus
- major one of two genera of stilts; similar to avocets but with straight bills
- genus Hippobosca
- type genus of the Hippoboscidae
- genus Hippocampus
- seahorses
- genus Hippodamia
- genus of ladybugs
- genus Hippoglossoides
- a genus of Pleuronectidae
- genus Hippoglossus
- halibuts
- genus Hippopotamus
- type genus of the Hippopotamidae
- genus Hipposideros
- horseshoe bats
- genus Hippotragus
- sable antelopes
- genus Hipsurus
- a genus of Embiotocidae
- genus Hirudo
- type genus of the family Hirudinidae
- genus Hirundo
- type genus of the Hirundinidae
- genus Holbrookia
- earless lizards
- genus Holocentrus
- type genus of the family Holocentridae; squirrelfishes
- genus Holothuria
- type genus of the Holothuridae
- genus Homarus
- type genus of the family Homaridae: common edible lobsters
- genus Homo
- type genus of the family Hominidae
- genus Homona
- tea tortrix
- genus Hyaena
- type genus of the Hyaenidae
- genus Hyalophora
- American silkworm moth
- genus Hydra
- hydras
- genus Hydrobates
- type genus of the Hydrobatidae
- genus Hydrochoerus
- a genus of Hydrochoeridae
- genus Hydrodamalis
- a genus of the family Dugongidae comprising only Steller's sea cow
- genus Hydromantes
- web-toed salamanders
- genus Hydromys
- water rats
- genus Hyemoschus
- water chevrotains
- genus Hyla
- the type genus of the Hylidae; tree toads
- genus Hylactophryne
- barking frogs
- genus Hylobates
- gibbons
- genus Hylocichla
- American thrush: wood thrush; hermit thrush; veery
- genus Hylophylax
- a genus of Formicariidae
- genus Hynerpeton
- earliest fossil amphibian ever found; of the Devonian; found in Pennsylvania
- genus Hypentelium
- a genus of fish in the family Catostomidae
- genus Hyperoglyphe
- a genus of Stromateidae
- genus Hyperoodon
- bottle-nosed whales
- genus Hyphantria
- fall webworms
- genus Hypoderma
- in some classifications considered the type genus of the family Hypodermatidae: warble flies
- genus Hypopachus
- sheep frogs
- genus Hypsiglena
- night snakes
- genus Hypsiprymnodon
- musk kangaroos
- genus Hyracotherium
- extinct horse genus; formerly called eohippus
- genus Ibero-mesornis
- a genus of fossil bird of the subclass Archaeornithes
- genus Ibis
- ibises
- genus Ichthyosaurus
- type genus of the Ichthyosauridae
- genus Ichthyostega
- second earliest fossil amphibian ever found; of the Devonian; found in Greenland
- genus Ictalurus
- channel catfishes
- genus Icteria
- New World chats
- genus Icterus
- type genus of the Icteridae
- genus Ictiobus
- buffalo fishes
- genus Ictonyx
- a genus of Mustelidae
- genus Iguana
- type genus of the Iguanidae
- genus Iguanodon
- type genus of the Iguanodontidae
- genus Inachis
- a genus of Nymphalidae
- genus Indri
- type genus of the Indriidae
- genus Irena
- type genus of the Irenidae: fairy bluebirds
- genus Iridoprocne
- a genus of Hirundinidae
- genus Ischigualastia
- early reptile found in Argentina
- genus Istiophorus
- type genus of the Istiophoridae
- genus Isurus
- mako sharks
- genus Ixobrychus
- bitterns
- genus Ixodes
- type genus of the family Ixodidae
- genus Jabiru
- jabirus
- genus Jaculus
- jerboas
- genus Javanthropus
- former genus of primitive man; now Homo soloensis: comprises Solo man
- genus Jordanella
- flagfishes
- genus Junco
- American finches
- genus Jynx
- wrynecks
- genus Kalotermes
- type genus of Kalotermitidae; termites destructive of wood and living trees
- genus Katsuwonus
- oceanic bonitos; in some classifications placed in its own family Katsuwonidae
- genus Kenyapithecus
- extinct primate having powerful chewing muscles along with large molars and small incisors; fossils found in Kenya
- genus Kinosternon
- type genus of the Kinosternidae
- genus Klebsiella
- a genus of bacteria
- genus Kobus
- African antelopes: waterbucks
- genus Kogia
- pygmy sperm whales
- genus Krypterophaneron
- a genus of fish in the family Anomalopidae
- genus Kyphosus
- type genus of the Kyphosidae
- genus Lacerta
- type genus of the Lacertidae
- genus Lachnolaimus
- a genus of Labridae
- genus Lactobacillus
- type genus of the family Lactobacillaceae
- genus Lactophrys
- a genus of Ostraciidae
- genus Lagidium
- a genus of Chinchillidae
- genus Lagodon
- a genus of Sparidae
- genus Lagopus
- ptarmigans
- genus Lagorchestes
- hare wallabies
- genus Lagostomus
- viscachas
- genus Lagothrix
- woolly monkeys
- genus Lama
- llamas
- genus Lambis
- scorpion shells of shallow tropical waters of the eastern hemisphere
- genus Laminaria
- type genus of the family Laminariaceae: perennial brown kelps
- genus Lamna
- a genus of Lamnidae
- genus Lampris
- type genus of the Lampridae
- genus Lampropeltis
- king snakes and milk snakes
- genus Lanius
- type genus of the Laniidae: typical shrikes
- genus Lanthanotus
- one species
- genus Larus
- type genus of the Laridae
- genus Lasiocampa
- type genus of the Lasiocampidae: eggars
- genus Lasiurus
- a genus of Vespertilionidae
- genus Lates
- a genus of large percoid fishes of fresh and brackish water
- genus Latimeria
- type genus of the Latimeridae: coelacanth
- genus Latrodectus
- venomous spiders
- genus Lebistes
- guppies
- genus Leiopelma
- type and sole genus of the family Leiopelmatidae
- genus Leipoa
- mallee fowl
- genus Leishmania
- flagellate protozoan that causes leishmaniasis
- genus Lemur
- type genus of the Lemuridae
- genus Leontocebus
- tamarins
- genus Lepas
- type genus of the family Lepadidae
- genus Lepidochelys
- ridleys
- genus Lepidocybium
- a genus of Gempylidae
- genus Lepisma
- type genus of the Lepismatidae: silverfish
- genus Lepisosteus
- type genus of the Lepisosteidae: freshwater gars
- genus Lepomis
- bream
- genus Leptinotarsa
- Colorado potato beetles
- genus Leptodactylus
- type genus of the Leptodactylidae; in some classifications placed in the family Bufonidae
- genus Leptoglossus
- leaf-footed bugs
- genus Leptoptilus
- adjutant birds and marabous
- genus Leptospira
- very slender aerobic spirochetes; free-living or parasitic in mammals
- genus Leptotyphlops
- blind snakes of Asia and Africa and Americas
- genus Lepus
- type genus of the Leporidae: hares
- genus Leuciscus
- a genus of fish including: dace, chub
- genus Leucocytozoon
- a genus of protoctist
- genus Lichanura
- boas of western North America
- genus Limanda
- a genus of Pleuronectidae; righteye flounders having a humped nose and small scales; the underside is often brightly colored
- genus Limax
- a genus of Limacidae
- genus Limenitis
- mainly dark northern butterflies with white wing bars
- genus Limnocryptes
- snipe
- genus Limnodromus
- dowitchers
- genus Limosa
- godwits
- genus Limulus
- type genus of the family Limulidae
- genus Liomys
- pocket mice
- genus Liparis
- type genus of the Liparididae: snailfishes
- genus Liposcelis
- a genus of Psocidae
- genus Listeria
- a genus of aerobic motile bacteria of the family Corynebacteriaceae containing small Gram-positive rods
- genus Litocranius
- antelopes of eastern Africa: gerenuks
- genus Littorina
- type genus of the family Littorinidae: periwinkles
- genus Lobipes
- a genus of Phalaropidae
- genus Lobotes
- type genus of the Lobotidae
- genus Locusta
- a genus of Acrididae
- genus Lofortyx
- California quail
- genus Loligo
- squids
- genus Lophius
- type genus of family Lophiidae
- genus Lophodytes
- a genus of Merginae
- genus Lopholatilus
- large brightly colored food fish of deep Atlantic waters
- genus Lophophorus
- monals
- genus Loris
- type genus of the Lorisidae
- genus Lota
- burbot
- genus Loxia
- crossbill
- genus Loxodonta
- a genus of Elephantidae
- genus Loxostege
- garden webworms
- genus Lucilia
- greenbottle flies
- genus Lufengpithecus
- a genus of Hominidae
- genus Lumpenus
- a genus of Stichaeidae
- genus Lunda
- puffins
- genus Luscinia
- nightingales
- genus Lutjanus
- type genus of the Lutjanidae: snappers
- genus Lutra
- in some classifications considered a genus of the subfamily Lutrinae
- genus Luvarus
- type genus of the Luvaridae
- genus Lycaena
- type genus of the Lycaenidae; small slender butterflies with upper surface of wings usually metallic blue or green or copper
- genus Lycaeon
- African hunting dog
- genus Lycosa
- type genus of the family Lycosidae
- genus Lygus
- plant-sucking bugs
- genus Lymantria
- type genus of the Lymantriidae; a pest (Lymantria means `destroyer')
- genus Lynx
- lynxes
- genus Lyrurus
- black grouse
- genus Macaca
- macaques; rhesus monkeys
- genus Macrocephalon
- maleos
- genus Macrocheira
- giant crabs of Japan
- genus Macroclemys
- includes the alligator snapping turtle
- genus Macrodactylus
- a genus of Melolonthidae
- genus Macronectes
- giant petrels
- genus Macropus
- type genus of the family Macropodidae: typical kangaroos and wallabies
- genus Macrotis
- a genus of Peramelidae
- genus Macrotus
- leafnose bats
- genus Macrozoarces
- a genus of Zoarcidae
- genus Madoqua
- genus comprising some small antelopes of eastern and northeastern Africa
- genus Maeandra
- brain corals
- genus Magicicada
- seventeen-year locust
- genus Maja
- type genus of the Majidae; nearly cosmopolitan in distribution
- genus Makaira
- marlins
- genus Malaclemys
- American terrapins
- genus Malacosoma
- tent caterpillars
- genus Mallotus
- capelins
- genus Malopterurus
- electric catfish
- genus Mammuthus
- extinct genus: mammoths
- genus Mandrillus
- baboons
- genus Manduca
- moths whose larvae are tobacco hornworms or tomato hornworms
- genus Manis
- type genus of the Manidae
- genus Manta
- a genus of Mobulidae
- genus Mantis
- type genus of the Mantidae: mantises
- genus Marmota
- marmots
- genus Martes
- martens
- genus Masticophis
- whip snakes
- genus Mastigoproctus
- giant whip scorpions
- genus Mastodon
- extinct type genus of the Mammutidae: mastodons
- genus Mastotermes
- primitive genus of termites; mostly extinct; sometimes considered the most primitive Isoptera
- genus Maxostoma
- a genus of fish in the family Catostomidae
- genus Mayetiola
- a genus of Cecidomyidae
- genus Mazama
- brockets
- genus Megachile
- type genus of the Megachilidae: leaf-cutting bees
- genus Megaderma
- type genus of the Megadermatidae
- genus Megalobatrachus
- giant salamanders; in some classifications included in the genus Cryptobranchus
- genus Megalosaurus
- type genus of the Megalosauridae
- genus Megaptera
- humpback whales
- genus Megatherium
- type genus of the Megatheriidae
- genus Melanerpes
- a genus of Picidae
- genus Melanitta
- scoters
- genus Melanogrammus
- haddock
- genus Melanoplus
- New World migratory locusts and common American grasshoppers
- genus Melanotis
- a genus of Mimidae
- genus Meleagris
- type genus of the Meleagrididae: wild and domestic turkeys
- genus Meles
- in some classifications: type genus of the subfamily Melinae
- genus Mellivora
- ratels
- genus Melogale
- a genus of Mustelidae
- genus Melolontha
- a genus of Melolonthidae
- genus Melophagus
- an arthropod genus of wingless flies including the sheep ked
- genus Melopsittacus
- a genus of Psittacidae
- genus Melospiza
- American song sparrow and swamp sparrow
- genus Melursus
- sloth bears; in some classifications not a separate genus from Ursus
- genus Menippe
- stone crabs
- genus Menopon
- chicken lice
- genus Menticirrhus
- kingfishes; whiting
- genus Menura
- type and sole genus of the family Menuridae
- genus Mephitis
- in some classifications: type genus of the subfamily Mephitinae
- genus Mercenaria
- a genus of Veneridae
- genus Mergus
- mergansers
- genus Meriones
- a genus of Cricetidae
- genus Merlangus
- whitings
- genus Merluccius
- hakes
- genus Merops
- type genus of the Meropidae
- genus Mesocricetus
- golden hamsters
- genus Mesohippus
- a genus of Equidae
- genus Microcentrum
- katydids
- genus Micrococcus
- type genus of the family Micrococcaceae
- genus Microdipodops
- kangaroo mice
- genus Micromyx
- Old World harvest mice
- genus Micropogonias
- croakers
- genus Micropterus
- American freshwater black basses
- genus Microstomus
- a genus of Pleuronectidae
- genus Microtus
- voles of the northern hemisphere
- genus Micruroides
- coral snakes
- genus Micrurus
- coral snakes
- genus Mimus
- type genus of the family Mimidae: mockingbirds
- genus Mirounga
- elephant seals
- genus Mobula
- type genus of the Mobulidae
- genus Mola
- type genus of the Molidae
- genus Mollienesia
- mollies
- genus Moloch
- genus of Australian desert lizard
- genus Molothrus
- cowbirds
- genus Molva
- ling
- genus Momotus
- type genus of the Momotidae
- genus Monocanthus
- type genus of the Monocanthidae
- genus Monochamus
- sawyer beetles
- genus Monodon
- type genus of the Monodontidae
- genus Monomorium
- a genus of Formicidae
- genus Mononychus
- authorities disagree over whether to classify the genus as bird or dinosaur
- genus Morone
- carnivorous fresh and salt water fishes
- genus Moschus
- musk deer
- genus Motacilla
- type genus of the Motacillidae: wagtails
- genus Mugil
- type genus of the Mugilidae: mullets
- genus Mulloidichthys
- a genus of Mullidae
- genus Mullus
- type genus of the Mullidae: goatfishes
- genus Muntiacus
- muntjacs
- genus Mus
- type genus of the Muridae: common house mice; the tips of the upper incisors have a square notch
- genus Musca
- type genus of the Muscidae: houseflies
- genus Muscardinus
- a genus of Gliridae
- genus Muscicapa
- type genus of the Muscicapidae
- genus Muscivora
- a genus of Tyrannidae
- genus Musophaga
- type genus of the Musophagidae
- genus Mustela
- type genus of the family Mustelidae: minks and weasels
- genus Mustelus
- smooth dogfishes
- genus Mya
- type genus of the family Myacidae
- genus Myadestes
- solitaires
- genus Mycobacterium
- nonmotile Gram-positive aerobic bacteria
- genus Mycoplasma
- type and sole genus of the family Mycoplasmataceae
- genus Mycteria
- a genus of storks of the family Ciconiidae now including only the American wood ibis
- genus Mycteroperca
- groupers
- genus Mylodon
- type genus of the Mylodontidae; sometimes included in family Megatheriidae
- genus Myocastor
- a genus of Capromyidae
- genus Myopus
- a genus of Cricetidae
- genus Myotis
- largest and most widely distributed genus of bats
- genus Myrmecia
- bulldog ants
- genus Myrmecobius
- banded anteater
- genus Myrmecophaga
- type genus of the Myrmecophagidae; South American ant bear
- genus Myrmeleon
- type genus of the Myrmeleontidae: antlions
- genus Mysis
- type genus of the family Mysidae
- genus Mytilus
- type genus of the family Mytilidae: smooth-shelled marine mussels
- genus Myxine
- type genus of the Myxinidae (typical hagfishes)
- genus Myxinikela
- fossil hagfishes
- genus Myxocephalus
- grubby
- genus Naemorhedus
- gorals
- genus Naja
- cobras
- genus Nanomia
- a genus of Siphonophora
- genus Nasalis
- proboscis monkeys
- genus Nasua
- coatis
- genus Natrix
- water snakes; a cosmopolitan genus
- genus Naucrates
- a genus of Carangidae
- genus Nautilus
- type genus and sole recent representative of the family Nautilidae
- genus Necturus
- a genus of Proteidae
- genus Negaprion
- lemon sharks
- genus Neoceratodus
- extant Australian lungfishes
- genus Neofiber
- round-tailed muskrat
- genus Neomys
- a genus of Soricidae
- genus Neophron
- a genus of Accipitridae
- genus Neotoma
- packrats
- genus Nepa
- type genus of the Nepidae: typical elongate-oval water scorpions
- genus Nephrops
- a genus of Nephropsidae
- genus Nerita
- type genus of the Neritidae
- genus Neritina
- a genus of Neritidae
- genus Nerodia
- North American water snakes
- genus Nesokia
- bandicoot rats
- genus Nestor
- a genus of Psittacidae
- genus Neurotrichus
- shrew moles
- genus Nimravus
- false sabertoothed tigers
- genus Nitella
- fragile branching stoneworts
- genus Nitrobacter
- rod-shaped soil bacteria
- genus Nitrosomonas
- ellipsoidal soil bacteria
- genus Noctiluca
- a genus of protoctist
- genus Noctua
- type genus of the Noctuidae: moths whose larvae are cutworms
- genus Nomia
- a genus of bee; some are important pollinators of legumes
- genus Nostoc
- type genus of the family Nostocaceae: freshwater blue-green algae
- genus Notechis
- tiger snakes
- genus Notemigonus
- golden shiners
- genus Nothosaurus
- a genus of Nothosauria
- genus Notomys
- jerboa rats
- genus Notonecta
- type genus of the Notonectidae: backswimmers
- genus Notophthalmus
- newts
- genus Notornis
- a genus of Rallidae
- genus Notoryctus
- type genus of the family Notoryctidae: comprising solely the marsupial mole
- genus Notropis
- shiners
- genus Nucifraga
- nutcrackers
- genus Numenius
- curlews
- genus Numida
- guinea fowl
- genus Nyctanassa
- American night herons
- genus Nyctereutes
- raccoon dogs
- genus Nycticebus
- a genus of Lorisidae
- genus Nycticorax
- Old World night herons
- genus Nyctimene
- East Indian fruit bats
- genus Nymphalis
- type genus of the Nymphalidae: mourning cloak butterflies
- genus Nymphicus
- a genus of Psittacidae
- genus Oceanites
- a genus of Hydrobatidae
- genus Ochotona
- type genus of the Ochotonidae
- genus Octopus
- type genus of the family Octopodidae
- genus Ocyurus
- snappers
- genus Odobenus
- type genus of the Odobenidae: walruses
- genus Odocoileus
- North American deer
- genus Odontophorus
- genus of Central and South American crested partridges resembling quails; sometimes placed in a distinct subfamily or isolated in a distinct family
- genus Oecanthus
- tree crickets
- genus Oedogonium
- type genus of Oedogoniaceae; freshwater green algae having long unbranched filaments; usually free-floating when mature
- genus Oenanthe
- wheatears
- genus Oestrus
- type genus of the Oestridae: sheep botflies
- genus Okapia
- okapis
- genus Oligoplites
- leatherjackets
- genus Ommastrephes
- a genus of Decapoda
- genus Oncorhynchus
- Pacific salmon including sockeye salmon; chinook salmon; chum salmon; coho salmon
- genus Ondatra
- muskrats
- genus Oniscus
- type genus of the Oniscidae; woodlice that cannot roll into a ball
- genus Onychogalea
- a genus of Macropodidae
- genus Onychomys
- grasshopper mice
- genus Opheodrys
- North American green snakes
- genus Ophiodon
- a genus of Ophiodontidae
- genus Ophiophagus
- king cobra
- genus Ophisaurus
- glass lizards
- genus Opisthocomus
- type genus of the Opisthocomidae: hoatzins
- genus Orchestia
- type genus of the family Orchestiidae
- genus Orcinus
- killer whales
- genus Oreamnos
- mountain goats
- genus Orectolobus
- carpet sharks
- genus Oreortyx
- mountain quail of western United States
- genus Oriolus
- type genus of the Oriolidae
- genus Ornithorhynchus
- type genus of the family Ornithorhynchidae
- genus Ortalis
- chachalacas
- genus Orthopristis
- a genus of Haemulidae
- genus Orthotomus
- tailorbirds
- genus Orycteropus
- coextensive with the family Orycteropodidae
- genus Oryctolagus
- Old World rabbits
- genus Oryx
- African antelopes: oryxes
- genus Oryzomys
- rice rats
- genus Osmerus
- type genus of the Osmeridae
- genus Ostrea
- type genus of the family Ostreidae
- genus Otaria
- type genus of the Otariidae
- genus Otis
- type genus of the Otididae: European bustard
- genus Otus
- a genus of Strigidae
- genus Ouranopithecus
- a genus of Hominidae
- genus Ovalipes
- a genus of Portunidae
- genus Ovibos
- consisting of the musk-ox
- genus Ovis
- sheep
- genus Oxybelis
- vine snakes
- genus Oxylebius
- a genus of Hexagrammidae
- genus Oxyura
- ruddy duck
- genus Oxyuranus
- taipans
- genus Pachycephala
- arboreal insectivorous birds
- genus Padda
- a genus of Ploceidae
- genus Pagellus
- sea breams
- genus Pagophila
- a genus of Laridae
- genus Pagophilus
- harp seals
- genus Pagrus
- a genus of Sparidae
- genus Pagurus
- type genus of the family Paguridae
- genus Palaemon
- type genus of the family Palaemonidae; widely distributed genus
- genus Paleacrita
- geometrid moths
- genus Palinurus
- type genus of the family Palinuridae
- genus Palometa
- a genus of Stromateidae
- genus Pan
- chimpanzees; more closely related to Australopithecus than to other pongids
- genus Pandion
- type genus of the Pandionidae
- genus Panonychus
- a genus of Tetranychidae
- genus Panthera
- lions; leopards; snow leopards; jaguars; tigers; cheetahs; saber-toothed tigers
- genus Papio
- baboons
- genus Paprilus
- a genus of Stromateidae
- genus Paracheirodon
- a genus of Characidae
- genus Paradoxurus
- palm civets
- genus Paralichthys
- a genus of Bothidae
- genus Paralithodes
- a genus of Lithodidae
- genus Paramecium
- freshwater ciliate with an oval body and long deep oral groove
- genus Paranthias
- a genus of Serranidae
- genus Paranthropus
- former classification for Australopithecus robustus
- genus Parascalops
- brewer's moles
- genus Parophrys
- a genus of Soleidae
- genus Parula
- type genus of the Parulidae: wood warblers
- genus Parus
- type genus of the family Paridae
- genus Passer
- type genus of the Passeridae
- genus Passerina
- a genus of small North American finches including the New World buntings
- genus Patella
- type genus of the family Patellidae: common European limpets
- genus Pavo
- peafowl
- genus Pecten
- type genus of the family Pectinidae: sea and bay scallops
- genus Pediculus
- type genus of Pediculidae: true lice infecting humans
- genus Pedioecetes
- sharp-tailed grouse
- genus Pedionomus
- plain wanderer
- genus Pelecanus
- type genus of the Pelecanidae
- genus Penelope
- a genus of guans (turkey-like arboreal birds valued as game and food birds)
- genus Peneus
- type genus of the family Peneidae
- genus Pennatula
- type genus of the family Pennatulidae: sea pens
- genus Perca
- type genus of the Percidae
- genus Percina
- a genus of Percidae
- genus Perdix
- a genus of Perdicinae
- genus Peridinium
- type genus of the family Peridiniidae
- genus Periophthalmus
- a genus of Gobiidae
- genus Peripatopsis
- type genus of Peripatopsidae; onychophorans of chiefly Asiatic and African tropical regions
- genus Peripatus
- type genus of Peripatidae; onychophorans of chiefly New World tropical regions
- genus Periplaneta
- cosmopolitan genus of large cockroaches
- genus Perisoreus
- Canada jays
- genus Peristedion
- in some classifications the type genus of the subfamily Peristediinae: armored sea robins
- genus Pernis
- a common European bird of prey; dull brown with white-streaked underparts
- genus Perodicticus
- a genus of Lorisidae
- genus Perognathus
- pocket mice
- genus Peromyscus
- New World wood mice
- genus Petaurista
- very large Asiatic flying squirrels
- genus Petaurus
- a genus of Phalangeridae
- genus Petrogale
- rock wallabies
- genus Petromyzon
- typical lampreys
- genus Pezophaps
- constituted by the extinct solitaire
- genus Phacochoerus
- warthogs
- genus Phaethon
- type genus of the Phaethontidae
- genus Phalacrocorax
- type genus: coextensive with the family Phalacrocoracidae
- genus Phalaenoptilus
- a genus of Caprimulgidae
- genus Phalanger
- type genus of the family Phalangeridae: cuscuses
- genus Phalangium
- type genus of the family Phalangiidae
- genus Phalaropus
- type genus of the Phalaropidae: phalaropes
- genus Pharomacrus
- a genus of Trogonidae
- genus Phascogale
- pouched mice
- genus Phascolarctos
- koalas
- genus Phasianus
- type genus of the Phasianidae: the typical pheasants
- genus Phenacomys
- North American voles
- genus Philaenus
- a genus of Cercopidae
- genus Philohela
- American woodcocks
- genus Philomachus
- ruffs
- genus Philophylla
- leaf miners
- genus Phlebotomus
- small bloodsucking sand flies that resemble moths
- genus Phoca
- type genus of the Phocidae: earless seals
- genus Phocoena
- porpoises
- genus Phoeniculus
- type and only genus of the family Phoeniculidae
- genus Phoenicurus
- Old World thrushes
- genus Pholas
- type genus of the family Pholadidae: piddocks
- genus Pholis
- type genus of the Pholidae: gunnels
- genus Photoblepharon
- a genus of fish in the family Anomalopidae
- genus Phoxinus
- minnows
- genus Phrynosoma
- horned lizards
- genus Phthirius
- true lice: crab lice
- genus Phthorimaea
- potato moths
- genus Phyllium
- type genus of the Phyllidae
- genus Phyllorhynchus
- leaf-nosed snakes
- genus Phylloscopus
- warblers
- genus Phyllostomus
- type genus of the family Phyllostomatidae
- genus Phylloxera
- type genus of the Phylloxeridae: plant lice
- genus Physa
- type genus of the Physidae; freshwater air-breathing snails
- genus Physalia
- Portuguese man-of-war
- genus Physeter
- type genus of the Physeteridae
- genus Pica
- magpies
- genus Picoides
- a genus of Picidae
- genus Picumnus
- a genus of Picidae
- genus Picus
- type genus of Picidae
- genus Pieris
- type genus of the Pieridae
- genus Pinctada
- pearl oysters
- genus Pineus
- a genus of Adelgidae
- genus Pinguinus
- great auk
- genus Pinicola
- a genus of Fringillidae
- genus Pinnotheres
- type genus of the family Pinnotheridae: pea crabs
- genus Pipa
- type genus of the Pipidae
- genus Pipile
- genus of large crested guans (the piping guans)
- genus Pipilo
- towhees
- genus Pipistrellus
- nearly cosmopolitan genus of very small bats
- genus Pipra
- type genus of the Pipridae containing the typical manakins
- genus Piranga
- a genus of Thraupidae
- genus Piroplasma
- type genus of the family Babesiidae
- genus Pisanosaurus
- primitive ornithischian dinosaur found in Argentina; early Triassic
- genus Pithecia
- sakis
- genus Pitta
- type genus of the Pittidae; a large genus of birds of southern Asia and Australia and adjacent islands
- genus Pituophis
- bull snakes
- genus Pitymys
- pine mice
- genus Placuna
- windowpane oysters
- genus Planococcus
- a genus of Pseudococcidae
- genus Plasmodium
- type genus of the family Plasmodiidae
- genus Platalea
- type genus of the Plataleidae
- genus Platichthys
- a genus of Pleuronectidae
- genus Platypoecilus
- platys
- genus Plautus
- a genus of Alcidae
- genus Plecotus
- a genus of Vespertilionidae
- genus Plectrophenax
- snow bunting
- genus Plesianthropus
- former name for the genus Australopithecus
- genus Plesiosaurus
- a reptile genus of suborder Plesiosauria
- genus Plethodon
- type genus of the Plethodontidae
- genus Pleurobrachia
- sea gooseberries
- genus Pleuronectes
- type genus of the Pleuronectidae
- genus Plicatoperipatus
- a genus of Peripatidae
- genus Ploceus
- type genus of the Ploceidae
- genus Pluvialis
- golden plovers
- genus Pluvianus
- coursers
- genus Podargus
- type genus of the Podargidae
- genus Podiceps
- type genus of the Podicipedidae: grebes
- genus Podilymbus
- a genus of Podicipedidae
- genus Poecilocapsus
- a genus of Miridae
- genus Poecilogale
- muishonds
- genus Poephila
- grassfinches
- genus Polioptila
- New World gnatcatchers
- genus Polistes
- a genus of Vespidae
- genus Pollachius
- pollack
- genus Polyangium
- type genus of the family Polyangiaceae: myxobacteria with rounded fruiting bodies enclosed in a membrane
- genus Polyborus
- a genus of Falconidae
- genus Polycirrus
- genus of soft-bodied polychete marine worms
- genus Polydactylus
- a genus of Polynemidae
- genus Polyergus
- Amazon ants
- genus Polygonia
- comma butterflies
- genus Polyodon
- type genus of the Polyodontidae
- genus Polypedates
- type genus of the Polypedatidae
- genus Polyprion
- wreckfish
- genus Pomacanthus
- angelfishes
- genus Pomacentrus
- type genus of the Pomacentridae: damselfishes
- genus Pomatomus
- type genus of the Pomatomidae
- genus Pomolobus
- genus to which the alewife is sometimes assigned
- genus Pomoxis
- crappies
- genus Pongo
- type genus of the family Pongidae: orangutans
- genus Pooecetes
- a genus of Fringillidae
- genus Popillia
- a genus of Scarabaeidae
- genus Porcellio
- Old World genus of isopod crustaceans
- genus Poronotus
- a genus of Stromateidae
- genus Porphyra
- a genus of protoctist
- genus Porphyrio
- Old World purple gallinules
- genus Porphyrula
- American purple gallinules
- genus Portunus
- type genus of the family Portunidae
- genus Porzana
- spotted crakes
- genus Potamogale
- type genus of the family Potamogalidae: otter shrews
- genus Potamophis
- ground snakes
- genus Potorous
- potoroos
- genus Potos
- a genus of Procyonidae
- genus Praunus
- a genus of Mysidae
- genus Priacanthus
- type genus of the Priacanthidae
- genus Prinia
- a genus of Sylviidae
- genus Priodontes
- solely the giant armadillo
- genus Prionace
- blue sharks
- genus Prionotus
- a genus of Triglidae
- genus Pristis
- type genus of the Pristidae
- genus Procavia
- type genus of the Procaviidae
- genus Procellaria
- type genus of the Procellariidae
- genus Prociphilus
- a genus of Aphididae
- genus Procnias
- bellbirds
- genus Proconsul
- genus of extinct primitive African primates of the Miocene epoch; sometimes considered a subgenus of Dryopithecus
- genus Procyon
- the type genus of the family Procyonidae: raccoons
- genus Progne
- a genus of Hirundinidae
- genus Prosopium
- whitefishes
- genus Proteles
- aardwolf
- genus Proterochampsa
- early archosaurian carnivore
- genus Proteus
- type genus of the Proteidae
- genus Protoavis
- extinct primitive birds of the Triassic period; 70 million years before archaeopteryx
- genus Protoceratops
- small horned dinosaurs
- genus Protohippus
- a genus of Equidae
- genus Prunella
- type genus of the Prunellidae
- genus Psaltriparus
- a genus of Paridae
- genus Psenes
- a genus of Stromateidae
- genus Psephurus
- a genus of Polyodontidae
- genus Psetta
- a genus of Bothidae
- genus Psettichthys
- a genus of Soleidae
- genus Pseudacris
- chorus frogs
- genus Pseudaletia
- moths whose larvae are armyworms
- genus Pseudechis
- venomous Australian blacksnakes
- genus Pseudemys
- sliders; red-bellied terrapin
- genus Pseudococcus
- type genus of the Pseudococcidae
- genus Pseudomonas
- type genus of the family Pseudomonodaceae
- genus Pseudopleuronectes
- a genus of Pleuronectidae
- genus Pseudoryx
- species of large cow-like mammals of Vietnam discovered by scientists in 1992
- genus Psithyrus
- a large bee that resembles the bumblebee but lacks pollen-collecting apparatus and a worker caste
- genus Psittacosaurus
- most primitive genus of horned dinosaurs; early Cretaceous
- genus Psittacula
- a genus of Psittacidae
- genus Psittacus
- type genus of the Psittacidae: usually restricted to the African grey
- genus Psophia
- type genus of the Psophiidae: trumpeters
- genus Pternohyla
- burrowing tree frogs
- genus Pterocles
- type genus of the Pteroclididae
- genus Pterocnemia
- a genus of birds of the family Rheidae
- genus Pterodactylus
- a reptile genus of Pterodactylidae
- genus Pterois
- lionfishes
- genus Pteropus
- a genus of Megachiroptera
- genus Ptilocercus
- pentails
- genus Ptilocrinus
- sea lilies
- genus Ptilonorhynchus
- type genus of the Ptilonorhynchidae
- genus Ptloris
- a genus of Paradisaeidae
- genus Ptyas
- Asian rat snakes
- genus Ptychozoon
- flying geckos
- genus Puffinus
- shearwaters
- genus Pulex
- type genus of the Pulicidae
- genus Pygopus
- type genus of the Pygopodidae; snake-shaped pleurodont lizard with no forelimbs and only rudimentary hind limbs
- genus Pygoscelis
- a genus of Spheniscidae
- genus Pylodictus
- flathead catfishes
- genus Pyralis
- type genus of the Pyralidae
- genus Pyrausta
- moths whose larvae are corn borers
- genus Pyrocephalus
- a genus of Tyrannidae
- genus Pyrophorus
- tropical click beetles
- genus Pyrrhula
- bullfinches
- genus Pyrrhuloxia
- large showy finches related to cardinals
- genus Python
- Old World boas
- genus Quiscalus
- grackles
- genus Rachycentron
- genus and family are coextensive and comprise only the cobia
- genus Raja
- type genus of the family Rajidae
- genus Ramphomicron
- thornbills
- genus Rana
- type genus of the Ranidae
- genus Ranatra
- elongate very slender water scorpions
- genus Rangifer
- reindeer or caribou
- genus Raphicerus
- African antelopes: steenboks
- genus Raphus
- type genus of the Raphidae: dodos
- genus Rattus
- common house rats; upper incisors have a beveled edge
- genus Recurvirostra
- type genus of the Recurvirostridae: avocets
- genus Regalecus
- type genus of the Regalecidae
- genus Regulus
- a genus of birds of the family Sylviidae including kinglets
- genus Reithrodontomys
- New World harvest mice
- genus Remilegia
- a genus of Echeneididae
- genus Reticulitermes
- includes species highly destructive to structures and living trees
- genus Rhagoletis
- a genus of Trypetidae
- genus Rhea
- type genus of the Rheidae; large tall flightless South American birds similar to but smaller than ostriches
- genus Rhincodon
- whale sharks
- genus Rhinoceros
- type genus of the Rhinocerotidae
- genus Rhinonicteris
- orange horseshoe bats
- genus Rhinoptera
- a genus of Myliobatidae
- genus Rhizobium
- the type genus of Rhizobiaceae; usually occur in the root nodules of legumes; can fix atmospheric oxygen
- genus Rhodymenia
- type genus of the family Rhodymeniaceae
- genus Rhyacotriton
- olympic salamanders
- genus Rhynchoelaps
- Australian coral snakes
- genus Richmondena
- cardinals
- genus Rickettsia
- can cause typhus and Rocky Mountain spotted fever in humans
- genus Riparia
- a genus of Hirundinidae
- genus Rissa
- a genus of Laridae
- genus Rivulus
- killifish
- genus Roccus
- a genus of Serranidae
- genus Rupicapra
- chamois
- genus Rupicola
- cock of the rocks
- genus Rutilus
- roaches
- genus Rynchops
- type genus of the Rynchopidae: skimmers
- genus Rypticus
- a genus of fish of the family Serranidae, including soapfishes
- genus Sagitta
- chief genus of Chaetognatha including the largest arrowworms
- genus Sagittarius
- type genus of the Sagittariidae
- genus Saiga
- Eurasian antelopes: saigas
- genus Saimiri
- squirrel monkeys
- genus Salamandra
- type genus of the Salamandridae
- genus Salmo
- type genus of the Salmonidae: salmon and trout
- genus Salmonella
- a genus of bacteria
- genus Salpa
- type (perhaps sole) genus of the Salpidae
- genus Salpinctes
- a genus of Troglodytidae
- genus Salvelinus
- brook trout
- genus Samia
- silkworm moths
- genus Sarcocystis
- chief genus of the order Sarcosporidia
- genus Sarcophaga
- flesh flies
- genus Sarcophilus
- Tasmanian devil
- genus Sarcoptes
- type genus of the family Sarcoptidae: itch mites
- genus Sarcorhamphus
- usually containing only the king vulture
- genus Sarda
- bonitos
- genus Sardinia
- pilchards
- genus Sardinops
- pilchards
- genus Sargassum
- a genus of protoctist
- genus Saturnia
- type genus of the Saturniidae: emperor moth
- genus Sauromalus
- chuckwallas
- genus Saurosuchus
- early archosaurian carnivore
- genus Saxicola
- Old World chats
- genus Sayornis
- phoebes
- genus Scaphiopus
- New World spadefoot toads
- genus Scarabaeus
- type genus of the Scarabaeidae
- genus Scardinius
- rudds
- genus Scartella
- a genus of Blenniidae
- genus Sceliphron
- mud daubers
- genus Sceloglaux
- a genus of Strigidae
- genus Sceloporus
- spiny lizards
- genus Schistosoma
- type genus of the family Schistosomatidae: blood flukes
- genus Sciaena
- type genus of the Sciaenidae: croakers
- genus Sciaenops
- a genus of Sciaenidae
- genus Sciara
- type genus of the Sciaridae: fungus gnat
- genus Scincella
- a reptile genus of Scincidae
- genus Scincus
- type genus of Scincidae
- genus Sciurus
- type genus of the Sciuridae; typical moderate-sized arboreal squirrels
- genus Scleropages
- a genus of large freshwater fishes of Australia and Borneo
- genus Scolopax
- type of the Scolopacidae: Old World woodcocks
- genus Scolytus
- type genus of the Scolytidae comprising numerous small bark beetles
- genus Scomber
- type genus of the Scombridae
- genus Scomberesox
- a genus of Scomberesocidae
- genus Scomberomorus
- Spanish mackerels
- genus Scophthalmus
- a genus of Bothidae
- genus Scorpaena
- type genus of the Scorpaenidae: scorpionfishes
- genus Scutigera
- a genus of Scutigeridae
- genus Scutigerella
- garden centipedes
- genus Sebastodes
- rockfishes
- genus Seismosaurus
- genus of large herbivorous dinosaurs of Cretaceous found in western North America
- genus Seiurus
- ovenbirds and water thrushes
- genus Selar
- big-eyed scad
- genus Selenarctos
- Asiatic black bears; in some classifications not a separate genus from Ursus
- genus Selene
- a genus of Carangidae
- genus Sepia
- type genus of the Sepiidae
- genus Serinus
- Old World finches; e.g. canaries and serins
- genus Seriola
- a genus of Carangidae
- genus Seriphus
- a genus of Sciaenidae
- genus Serranus
- type genus of the Serranidae: mostly small Pacific sea basses
- genus Serrasalmus
- piranhas
- genus Serratia
- a genus of motile peritrichous bacteria that contain small Gram-negative rod
- genus Sertularia
- sessile hydroid that forms feathery colonies
- genus Setophaga
- a genus of Parulidae
- genus Shigella
- a genus of bacteria
- genus Sialia
- North American bluebirds
- genus Sialis
- type genus of the Sialidae
- genus Sigmodon
- American cotton rats
- genus Sillago
- type genus of the Sillaginidae
- genus Silurus
- type genus of the Siluridae: catfishes
- genus Silvia
- type genus of the Sylviidae: warblers
- genus Simulium
- type genus of the Simuliidae: blackflies
- genus Sinanthropus
- genus to which Peking man was formerly assigned
- genus Sinornis
- a genus of fossil birds
- genus Siren
- a genus of Sirenidae
- genus Sistrurus
- pygmy rattlesnakes
- genus Sitophylus
- a genus of Bruchidae
- genus Sitotroga
- grain moths
- genus Sitta
- type genus of the Sittidae
- genus Sivapithecus
- extinct primates; lower Pliocene
- genus Smiledon
- saber-toothed tigers
- genus Solea
- type genus of the Soleidae
- genus Solenopsis
- fire ants
- genus Somateria
- eider ducks
- genus Sonora
- ground snakes
- genus Sorex
- type genus of the family Soricidae: shrews
- genus Spadella
- marine worms resembling the sagittas but with a broader body and only one pair of lateral fins
- genus Spalax
- type genus of the Spalacidae
- genus Spermophilus
- typical ground squirrels
- genus Sphecius
- large solitary wasps: cicada killer
- genus Sphecotheres
- a genus of Old World orioles
- genus Spheniscus
- type genus of the Spheniscidae: jackass penguins
- genus Sphenodon
- coextensive with the order Rhynchocephalia: tuataras
- genus Sphyraena
- type and sole genus of the Sphyraenidae: barracuda
- genus Sphyrapicus
- a genus of Picidae
- genus Sphyrna
- type genus of the Sphyrnidae
- genus Spilogale
- a genus of Mustelidae
- genus Spinus
- in some classifications considered a subgenus of Carduelis: siskins and New World goldfinches
- genus Spirillum
- a genus of bacteria
- genus Spirochaeta
- the type genus of the family Spirochaetaceae; a bacterium that is flexible, undulating, and chiefly aquatic
- genus Spirogyra
- a genus of protoctist
- genus Spirula
- genus of small cephalopods with many-chambered spiral shells resembling those of the extinct belemnites
- genus Spizella
- chipping sparrow; field sparrow; tree sparrow
- genus Spodoptera
- moths whose larvae are armyworms
- genus Spyeria
- fritillaries
- genus Squalus
- spiny dogfishes
- genus Squatina
- type genus of the Squatinidae: angel sharks
- genus Squilla
- type genus of the family Squillidae
- genus Staphylococcus
- includes many pathogenic species
- genus Staurikosaurus
- primitive ornithischian dinosaur found in Brazil
- genus Steatornis
- type and sole genus of the family Steatornithidae
- genus Steganopus
- a genus of Phalaropidae
- genus Stegosaurus
- quadrupedal armored herbivore of the Jurassic and Cretaceous
- genus Stenopelmatus
- sand crickets
- genus Stenopterygius
- a reptile genus of Ichthyosauridae
- genus Stenotomus
- scups
- genus Stentor
- trumpet-shaped protozoa with a ciliated spiral feeding funnel
- genus Stercorarius
- type genus of the Stercorariidae: jaegers
- genus Sterna
- a genus of Sterninae
- genus Sternotherus
- musk turtles
- genus Stictomys
- mountain pacas
- genus Stictopelia
- a genus of Columbidae
- genus Stizostedion
- pike-perches
- genus Storeria
- a genus of Colubridae
- genus Strepera
- bell magpies
- genus Strepsiceros
- African antelopes: kudus; bongos; nyalas; bushbucks
- genus Streptococcus
- a genus of bacteria
- genus Streptomyces
- type genus of the family Streptomycetaceae
- genus Streptopelia
- turtledoves
- genus Strix
- owls lacking ear tufts
- genus Strombus
- type genus of the family Strombidae
- genus Struthio
- type genus of the Struthionidae: African ostriches
- genus Struthiomimus
- small toothless saurischian dinosaurs; later Cretaceous period in Canada
- genus Strymon
- large and widely distributed genus of hairstreak butterflies
- genus Sturnella
- a genus of passerine birds including the meadowlarks
- genus Sturnus
- type genus of the Sturnidae: common starlings
- genus Styracosaurus
- genus of horned dinosaurs
- genus Sula
- type genus of the Sulidae
- genus Suricata
- meerkats
- genus Surnia
- a genus of hawk-like owls
- genus Sus
- type genus of the Suidae
- genus Sylvilagus
- North American rabbits
- genus Symphalangus
- used in some classifications for the siamangs
- genus Synagrops
- a genus of Serranidae
- genus Synanceja
- stonefishes
- genus Synaptomys
- bog lemmings
- genus Synercus
- Cape buffalo
- genus Syngnathus
- type genus of the family Syngnathidae
- genus Syrrhaptes
- a genus of Pteroclididae
- genus Tachyglossus
- type genus of the family Tachyglossidae
- genus Tachypleus
- a genus of Limulidae
- genus Tadarida
- freetail bats
- genus Tadorna
- sheldrakes
- genus Taenia
- type genus of the family Taeniidae: tapeworms
- genus Tamandua
- lesser anteater
- genus Tamias
- chipmunks of eastern North America
- genus Tamiasciurus
- American red squirrels
- genus Tantilla
- black-headed snakes
- genus Tapirus
- type genus of the Tapiridae
- genus Taricha
- Pacific newts
- genus Tarpon
- tarpons
- genus Tarsius
- type and sole genus of the family Tarsiidae
- genus Taurotragus
- African antelopes: elands
- genus Tautoga
- tautogs
- genus Tautogolabrus
- a genus of Labridae
- genus Taxidea
- in some classifications considered a genus of subfamily Melinae
- genus Tayassu
- type genus of the Tayassuidae
- genus Tenrec
- type genus of the family Tenrecidae: tenrecs
- genus Terebella
- type genus of Terebellidae; tube-forming marine polychete worms with many filamentous tentacles
- genus Teredo
- type genus of the family Teredinidae
- genus Termes
- type genus of the Termitidae
- genus Terrapene
- box turtles
- genus Testudo
- type genus of the Testudinidae
- genus Tetragonurus
- a genus of Stromateidae
- genus Tetrahymena
- protozoa having four membranous ciliary organelles
- genus Tetrao
- type genus of the Tetraonidae: capercaillies
- genus Tetrapturus
- a genus of Istiophoridae
- genus Thalarctos
- polar bears; in some classifications not a separate genus from Ursus
- genus Thalassoma
- a genus of Labridae
- genus Thamnophilus
- a genus of Formicariidae
- genus Thamnophis
- garter snakes
- genus Thermobia
- a genus of Lepismatidae
- genus Thiobacillus
- a genus of bacteria
- genus Thomomys
- western pocket gophers
- genus Threskiornis
- type genus of the Threskiornithidae
- genus Thrips
- type genus of the Thripidae
- genus Thryothorus
- Carolina wrens
- genus Thunnus
- tunas: warm-blooded fishes
- genus Thylacinus
- Tasmanian wolf
- genus Thylogale
- pademelons
- genus Tibicen
- harvest flies
- genus Tichodroma
- wall creepers; in some classifications placed in family Sittidae
- genus Tilapia
- a genus of Cichlidae
- genus Timalia
- type genus of the Timaliidae
- genus Tinca
- tench
- genus Tinea
- type genus of the Tineidae: clothes moths
- genus Tineola
- webbing clothes moths
- genus Titanosaurus
- genus of herbivorous dinosaurs flourishing during the Cretaceous in South America
- genus Todus
- type genus of the Todidae
- genus Tolypeutes
- a genus of Dasypodidae
- genus Tomistoma
- a genus of Malayan crocodiles
- genus Tortrix
- type genus of the Tortricidae
- genus Toxostoma
- thrashers
- genus Toxotes
- type genus of the Toxotidae
- genus Trachinotus
- a genus of Carangidae
- genus Trachipterus
- type genus of the Trachipteridae
- genus Trachodon
- a reptile genus of the suborder Euronithopoda
- genus Trachurus
- the scads (particularly horse mackerels)
- genus Tragopan
- a genus of Phasianidae
- genus Tragulus
- type genus of the Tragulidae
- genus Treponema
- type genus of Treponemataceae: anaerobic spirochetes with an undulating rigid body; parasitic in warm-blooded animals
- genus Triaenodon
- a genus of Triakidae
- genus Trialeurodes
- a genus of Aleyrodidae
- genus Triatoma
- conenoses
- genus Tribolium
- flour beetles
- genus Tribonema
- type genus of Tribonemaceae
- genus Triceratops
- genus of herbivorous horned dinosaurs
- genus Trichecus
- type and sole genus of the Trichechidae
- genus Trichodesmium
- a genus of blue-green algae
- genus Trichoglossus
- a genus of Loriinae
- genus Trichomonas
- flagellates parasitic in alimentary or genitourinary tracts of vertebrates and invertebrates including humans
- genus Trichophaga
- carpet moths
- genus Trichosurus
- a genus of Phalangeridae
- genus Trichys
- a genus of Hystricidae
- genus Tridacna
- type genus of the family Tridacnidae: giant clams
- genus Triga
- type genus of the Triglidae
- genus Trimorphodon
- lyre snakes
- genus Trinectes
- a genus of Soleidae
- genus Tringa
- a genus of Scolopacidae
- genus Trionyx
- type genus of the Trionychidae
- genus Triops
- type genus of the family Triopidae: small crustaceans with a small third median eye
- genus Triturus
- chiefly aquatic salamanders
- genus Trogium
- a genus of Psocidae
- genus Troglodytes
- type genus of the Troglodytidae
- genus Trogon
- type genus of the Trogonidae
- genus Trombicula
- type genus of the family Trombiculidae
- genus Tropidoclonion
- lined snakes
- genus Tunga
- a genus of Siphonaptera
- genus Tupaia
- the type genus of the Tupaia: chief genus of tree shrews
- genus Tupinambis
- tejus
- genus Turdus
- type genus of the Turdidae
- genus Turnix
- type genus of the Turnicidae: button quail
- genus Tursiops
- a genus of Delphinidae
- genus Tylenchus
- type genus of the family Tylenchidae
- genus Tympanuchus
- prairie chickens
- genus Tyrannosaurus
- includes a single species
- genus Tyrannus
- type genus of the Tyrannidae: tyrant flycatchers
- genus Tyto
- type and only genus of the family Tytonidae
- genus Uca
- fiddler crabs
- genus Uintatherium
- type genus of the Uintatheriidae; extinct large herbivorous ungulates somewhat resembling elephants; from the Eocene in Wyoming
- genus Ulva
- type genus of the family Ulvaceae; green seaweed having a thallus two cells thick: sea lettuce
- genus Uma
- fringe-toed lizard
- genus Umbrina
- croakers
- genus Unio
- type genus of the family Unionidae
- genus Upupa
- type genus of the Upupidae
- genus Uria
- murres
- genus Urocyon
- grey foxes
- genus Urophycis
- hakes
- genus Uropsilus
- shrew moles
- genus Urosaurus
- a reptile genus of Iguanidae
- genus Ursus
- type genus of Ursidae: brown bears; in some classifications genus Ursus includes all bears
- genus Uta
- a reptile genus of Iguanidae
- genus Utahraptor
- advanced bipedal carnivorous dinosaur
- genus Vanellus
- Eurasian lapwings
- genus Vanessa
- painted beauty and red admiral
- genus Varanus
- type and sole extant genus of the Varanidae
- genus Vedalia
- genus of Australian ladybugs
- genus Velociraptor
- advanced carnivorous theropod
- genus Venus
- type genus of the family Veneridae: genus of edible clams with thick oval shells
- genus Vespa
- type genus of the Vespidae: various hornets and yellow jackets
- genus Vespertilio
- a genus of Vespertilionidae
- genus Vespula
- sometimes considered a subgenus of Vespa: social wasps
- genus Vibrio
- a genus of bacteria
- genus Vicugna
- a genus of Camelidae
- genus Vidua
- whydahs
- genus Vipera
- type genus of the Viperidae
- genus Vireo
- type genus of the Vireonidae
- genus Viverra
- type genus of the family Viverridae
- genus Viverricula
- a genus of Viverridae
- genus Volvox
- type genus of the Volvocaceae; minute pale green flagellates occurring in tiny spherical colonies; minute flagella rotate the colony about an axis
- genus Vorticella
- ciliated protozoans that have a goblet-shaped body with a retractile stalk
- genus Vulpes
- foxes
- genus Vultur
- a bird that is usually restricted to the Andean condor
- genus Xanthomonas
- a genus of bacteria similar to Pseudomonas but producing a yellow pigment that is not soluble in water
- genus Xenicus
- type genus for the Xenicidae
- genus Xenopus
- an African clawed frog; in some classifications made the type genus of a separate family Xenopodidae
- genus Xenorhyncus
- East Indian and Australian storks
- genus Xenosaurus
- type and sole genus of Xenosauridae: slender-bodied Mexican lizards having the upper surface covered with tiny granules and tubercles
- genus Xerobates
- possible new genus for desert and Texas tortoises based on recent research
- genus Xiphias
- type genus of the Xiphiidae
- genus Xylocopa
- carpenter bees
- genus Xyphophorus
- swordtails
- genus Zaglossus
- a genus of Tachyglossidae
- genus Zalophus
- sea lions
- genus Zapus
- type genus of the Zapodidae
- genus Zenaidura
- mourning doves
- genus Zeus
- type genus of the family Zeidae
- genus Zinjanthropus
- genus to which Australopithecus boisei was formerly assigned
- genus Zoarces
- type genus of the Zoarcidae
- genus Zonotrichia
- large New World sparrows
- genus Zygnema
- type genus of the family Zygnemataceae
- genus-Fenusa
- birch leaf miner
- genus-Megapodius
- type genus of the Megapodiidae
- genus-Milvus
- a genus including the common European kits
- Genyonemus lineatus
- small silvery marine food fish found off California
- Geococcyx californianus
- speedy largely terrestrial bird found from California and Mexico to Texas
- geoduck
- a large edible clam found burrowing deeply in sandy mud along the Pacific coast of North America; weighs up to six pounds; has siphons that can extend to several feet and cannot be withdrawn into the shell
- geometrid
- slender-bodied broad-winged moth whose larvae are called measuring worms
- Geomys bursarius
- gopher of chiefly grasslands of central North America
- Geomys pinetis
- gopher of Alabama and Georgia and Florida
- gerbil
- small Old World burrowing desert rodent with long soft pale fur and hind legs adapted for leaping
- germ layer
- (embryology) any of the 3 layers of cells differentiated in embryos following gastrulation
- German bee
- dark-colored ill-tempered honeybee supposedly of German origin
- German shepherd dog
- breed of large shepherd dogs used in police work and as a guide for the blind
- German short-haired pointer
- liver or liver-and-white hunting dog developed in Germany; 3/4 pointer and 1/4 bloodhound
- Gerres cinereus
- popular panfish from Bermuda and Gulf of Mexico to Brazil
- Gerris lacustris
- a variety of water strider
- giant
- any creature of exceptional size
- giant cockroach
- large tropical American cockroaches
- giant schnauzer
- a large schnauzer
- giant silkworm moth
- any silkworm moth of the family Saturniidae
- giant silkworm
- larva of a saturniid moth; spins a large amount of strong silk in constructing its cocoon
- giant tortoise
- very large tortoises of the Galapagos and Seychelles islands
- giant water bug
- large water bug with piercing and sucking mouthparts; feeds on young fishes
- giardia
- a suspected cause of diarrhea in humans
- gib
- a castrated tomcat
- Ginglymostoma cirratum
- small bottom-dwelling shark of warm shallow waters on both coasts of North America and South America and from southeast Asia to Australia
- Giraffa camelopardalis
- tallest living quadruped; having a spotted coat and small horns and very long neck and legs; of savannahs of tropical Africa
- glareole
- Old World shorebird with long pointed wings and short legs; closely related to the coursers
- glass lizard
- snakelike lizard of Europe and Asia and North America with vestigial hind limbs and the ability to regenerate its long fragile tail
- glass sponge
- a siliceous sponge (with glassy spicules) of the class Hyalospongiae
- Glaucomys sabrinus
- large flying squirrel; chiefly of Canada
- Glaucomys volans
- small large-eyed nocturnal flying squirrel of eastern United States
- gliding bacteria
- bacteria that form colonies in self-produced slime; inhabit moist soils or decaying plant matter or animal waste
- Glis glis
- large European dormouse
- Globicephala melaena
- small dark-colored whale of the Atlantic coast of the United States; the largest male acts as pilot or leader for the school
- globigerina
- marine protozoan having a rounded shell with spiny processes
- glossina
- bloodsucking African fly; transmits sleeping sickness etc.
- Glossopsitta versicolor
- lorikeet with a colorful coat
- glowworm
- the luminous larva or wingless grub-like female of a firefly
- gnat
- (British usage) mosquito
- gnat
- any of various small biting flies: midges; biting midges; black flies; sand flies
- gnatcatcher
- very small North American and South American warblers
- gnathostome
- a vertebrate animal possessing true jaws
- gnawer
- relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing
- gnawing mammal
- relative large gnawing animals; distinguished from rodents by having two pairs of upper incisors specialized for gnawing
- gnu
- large African antelope having a head with horns like an ox and a long tufted tail
- goat antelope
- bovid related to goats but having antelope-like features: mountain goats; gorals; serows; chamois; gnu goats
- gobbler
- male turkey
- Gobiesox strumosus
- clingfish with typical skillet shape
- Gobio gobio
- small slender European freshwater fish often used as bait by anglers
- goby
- small spiny-finned fish of coastal or brackish waters having a large head and elongated tapering body having the ventral fins modified as a sucker
- godwit
- large wading bird that resembles a curlew; has a long slightly upturned bill
- golden algae
- algae having the pigments chlorophyll and carotene and xanthophyll
- golden mole
- mole of southern Africa having iridescent guard hairs mixed with the underfur
- golden plover
- plovers of Europe and America having the backs marked with golden-yellow spots
- golden retriever
- an English breed having a long silky golden coat
- goldeneye
- a variety of green lacewing
- gomphothere
- extinct elephants of Central American and South America; of the Miocene and Pleistocene
- Gonorhynchus gonorhynchus
- fish of sandy areas of western Pacific and Indian oceans having an angular snout for burrowing into sand
- goose
- web-footed long-necked typically gregarious migratory aquatic birds usually larger and less aquatic than ducks
- goose down
- down of the goose
- gopher
- any of various terrestrial burrowing rodents of Old and New Worlds; often destroy crops
- gopher
- burrowing rodent of the family Geomyidae having large external cheek pouches; of Central America and southwestern North America
- Gopherus agassizii
- burrowing tortoise of the arid western United States and northern Mexico; may be reclassified as a member of genus Xerobates
- Gopherus polypemus
- burrowing edible land tortoise of southeastern North America
- Gordon setter
- a Scottish breed with a black-and-tan coat
- gorgonian
- corals having a horny or calcareous branching skeleton
- Gorilla gorilla
- largest anthropoid ape; terrestrial and vegetarian; of forests of central west Africa
- Gorilla gorilla beringei
- gorilla of Kivu highlands
- Gorilla gorilla gorilla
- a kind of gorilla
- Gorilla gorilla grauri
- a kind of gorilla
- gosling
- young goose
- gracilariid
- small dull or metallic-colored tineoid moths whose larvae mine in plant leaves
- Gracula religiosa
- glossy black Asiatic starling often taught to mimic speech
- grade
- a variety of cattle produced by crossbreeding with a superior breed
- grain moth
- moth whose larvae feed on grain
- Grampus griseus
- slaty-grey blunt-nosed dolphin common in northern seas
- grass finch
- usually brightly-colored Australian weaverbirds; often kept as cage birds
- grass snake
- either of two North American chiefly insectivorous snakes that are green in color
- grasshopper mouse
- insectivorous mouse of western North America
- grasshopper
- terrestrial plant-eating insect with hind legs adapted for leaping
- gray hen
- female black grouse
- gray lemming
- Old World lemming
- gray mullet
- freshwater or coastal food fishes a spindle-shaped body; found worldwide
- gray
- horse of a light gray or whitish color
- great ape
- any of the large anthropoid apes of the family Pongidae
- Great Dane
- very large powerful smooth-coated breed of dog
- Great Pyrenees
- bred of large heavy-coated white dogs resembling the Newfoundland
- Greater Swiss Mountain dog
- the largest of the four Swiss breeds
- grebe
- small compact-bodied almost completely aquatic bird that builds floating nests; similar to loons but smaller and with lobate rather than webbed feet
- green gland
- one of a pair of glands (believed to have excretory functions) in some crustaceans near the base of the large antennae
- green June beetle
- large greenish June beetle of southern United States
- green mamba
- green phase of the black mamba
- green peach aphid
- yellowish green aphid that is especially destructive to peaches
- green plover
- large crested Old World plover having wattles and spurs
- green snake
- any of numerous African colubrid snakes
- greenbottle
- blowfly with brilliant coppery green body
- greeneye
- bottom-dwellers having large eyes with metallic green luster
- greenfly
- greenish aphid; pest on garden and crop plants
- greenling
- food fish of the northern Pacific
- gregarine
- vermiform protozoans parasitic in insects and other invertebrates
- grenadier
- deep-sea fish with a large head and body and long tapering tail
- greyhound
- a tall slender dog of an ancient breed noted for swiftness and keen sight; used as a racing dog
- griffon
- breed of medium-sized long-headed dogs with downy undercoat and harsh wiry outer coat; originated in Holland but largely developed in France
- groenendael
- black-coated sheepdog with a heavily plumed tail
- grosbeak
- any of various finches of Europe or America having a massive and powerful bill
- ground roller
- Madagascan roller with terrestrial and crepuscular habits that feeds on e.g. insects and worms
- ground sloth
- gigantic extinct terrestrial sloth-like mammal of the Pliocene and Pleistocene in America
- ground-shaker
- huge herbivorous dinosaur of the Cretaceous found in western North America
- grouper
- usually solitary bottom sea basses of warm seas
- grouse
- popular game bird having a plump body and feathered legs and feet
- grub
- a soft thick wormlike larva of certain beetles and other insects
- grunt
- medium-sized tropical marine food fishes that utter grunting sounds when caught
- Grus americana
- rare North American crane having black-and-white plumage and a trumpeting call
- guan
- any of several large turkey-like game birds of the family Cracidae; native to jungles of tropical America; resembling the curassows and valued as food
- guard dog
- a dog trained to guard property
- guard hair
- coarse hairs that form the outer fur and protect the underfur of certain mammals
- guenon
- small slender African monkey having long hind limbs and tail and long hair around the face
- Guernsey
- breed of dairy cattle from the island of Guernsey
- guide dog
- a dog trained to guide the blind
- guillemot
- small black or brown speckled auks of northern seas
- guinea hen
- female guinea fowl
- guitarfish
- primitive tropical bottom-dwelling ray with a guitar-shaped body
- gull
- mostly white aquatic bird having long pointed wings and short legs
- Gulo gulo
- musteline mammal of northern Eurasia
- Gulo luscus
- stocky shaggy-coated North American carnivorous mammal
- gun dog
- a dog trained to work with sportsmen when they hunt with guns
- gurnard
- bottom-dwelling coastal fishes with spiny armored heads and fingerlike pectoral fins used for crawling along the sea bottom
- Gymnelis viridis
- brightly colored scaleless Arctic eelpout
- Gymnogyps californianus
- North American condor; chiefly dull black; almost extinct
- Gymnorhina tibicen
- crow-sized black-and-white bird; a good mimic often caged
- Gypaetus barbatus
- the largest Eurasian bird of prey; having black feathers hanging around the bill
- Gyps fulvus
- large vulture of southern Europe and northern Africa having pale plumage with black wings
- hack
- a saddle horse used for transportation rather than sport etc.
- hack
- a horse kept for hire
- hack
- an old or over-worked horse
- hackle
- long slender feather on the necks of e.g. turkeys and pheasants
- hackney
- a compact breed of harness horse
- Haematobia irritans
- small black European fly introduced into North America; sucks blood from cattle especially at the base of the horn
- haemoproteid
- related to malaria parasite and having a phase in the viscera of various birds
- haemosporidian
- minute protozoans parasitic at some stage of the life cycle in blood cells of vertebrates including many pathogens
- Haemulon album
- a grunt with a red mouth that is found from Florida to Brazil
- Haemulon aurolineatum
- found off the West Indies and Florida
- Haemulon macrostomum
- a kind of grunt
- Haemulon malanurum
- of warm Atlantic waters
- Haemulon parra
- a grunt found from Florida to Brazil and Gulf of Mexico
- hag
- eellike cyclostome having a tongue with horny teeth in a round mouth surrounded by eight tentacles; feeds on dead or trapped fishes by boring into their bodies
- hair
- a filamentous projection or process on an organism
- hairstreak
- small butterflies having striped markings under the wings
- hake
- any of several marine food fishes related to cod
- halcyon
- a mythical bird said to breed at the time of the winter solstice in a nest floating on the sea and to have the power of calming the winds and waves
- halfbeak
- tropical and subtropical marine and freshwater fishes having an elongated body and long protruding lower jaw
- Haliaeetus leucocephalus
- a large eagle of North America that has a white head and dark wings and body
- Haliaeetus leucorhyphus
- of southeast Europe and central Asia
- Haliatus albicilla
- bulky greyish-brown eagle with a short wedge-shaped white tail; of Europe and Greenland
- halibut
- marine food fish of the northern Atlantic or northern Pacific; the largest flatfish and one of the largest teleost fishes
- Halicoeres bivittatus
- small wrasse of tropical Atlantic
- Halicoeres radiatus
- bluish and bronze wrasse; found from Florida keys to Brazil
- Haliotis tuberculata
- an abalone found near the Channel Islands
- halobacter
- halophiles in saline environments such as the Dead Sea or salt flats
- halophil
- archaebacteria requiring a salt-rich environment for growth and survival
- hammerhead
- medium-sized live-bearing shark with eyes at either end of a flattened hammer-shaped head; worldwide in warm waters; can be dangerous
- Hampshire down
- British breed of hornless dark-faced domestic sheep
- hamster
- short-tailed Old World burrowing rodent with large cheek pouches
- hand
- terminal part of the forelimb in certain vertebrates (e.g. apes or kangaroos)
- handsaw fish
- a soft-finned fish of the genus Alepisaurus
- hanging fly
- any of various mecopterous insects of the family Bittacidae
- haploid
- (genetics) an organism or cell having only one complete set of chromosomes
- haplosporidian
- parasite in invertebrates and lower vertebrates of no known economic importance
- hard tick
- ticks having a hard shield on the back and mouth parts that project from the head
- hard-shell crab
- edible crab that has not recently molted and so has a hard shell
- hare
- swift timid long-eared mammal larger than a rabbit having a divided upper lip and long hind legs; young born furred and with open eyes
- hare wallaby
- small Australian wallaby that resembles a hare and has persistent teeth
- harness horse
- horse used for pulling vehicles
- harnessed antelope
- any of several antelopes of the genus Tragelaphus having striped markings resembling a harness
- Harpia harpyja
- large black-and-white crested eagle of tropical America
- harpy
- any of various fruit bats of the genus Nyctimene distinguished by nostrils drawn out into diverging tubes