abalone
Acarina (mites and ticks)
Acathocephala (spiny-headed worms)
acclimatization
acorn worm
Actinopterygii (ray-finned fish)
adder
Agnatha (jawless fish)
air sac
albino
alternation of generations
amoeba
amphibian
amphipod
anhydrobiosis
animal animal behavior
animal cell
animals' mathematical ability
Annelida (true worms)
ant
antenna
Anura (frogs and toads)
ape
aphid
Apoda (caecilians)
arachnid
arthropod
Artiodactyla
asexual reproduction
axolotl

baleen
barnacle
basking shark
bat
beak
bee
beetle
beluga whale
benthos
binocular vision
bioelectricity
biological clock
bioluminescence
bird
bird life and variety
birds, anatomy
birds, classification
birds, reproduction
bivalve
blowhole
blue whale
book lung
boa
bottlenose dolphin
bowhead whale
brachiopod
bryozoan
budding
butterflies and moths

camouflage
carapace
Carnivora
carnivore
caterpillar
cat (domestic) anatomy
centipede
cephalic index
Cephalochordata
cephalopod
cephalothorax
cerci
cetacean
Chaetognatha
chelicerae
Chelonia
Chiroptera
Chondrichthyes
chordate
chromatophore
chrysalis
cicada
ciliate
cnidarian
cobra
cocoon
cod, anatomy
coelacanth
Coleoptera
compound eye
copepod
coral
cow, anatomy
crab
cremaster
crinoid
Crocodilia
crustacean
cryobiology
cryptobiosis
Ctenophora (comb jellies)
cuticle
cuttlefish

decapod
diapause
dinoflagellate
diploblastic
Diplopoda
Diptera
discus fish
dormancy
drone
Drosophila
duck-billed platypus

ecdysone
echinoderm
Echiuroidea
edentate
elephant
endoskeleton
Eutheria
exoskeleton

feather
fish
fish, adaptations and forms
fish, unusual
flagellate
flatworm
flea
flight
foraminifer
fur

gastropod
gill
glow-worm
Gnathostomata
gorilla
growth

halteres
harvestman
hedgehog
hemichordata
Hemiptera hemocoel
hen
herbivore
hermaphrodite
hibernation
hippopotamus
homeotherm
hookworm
horn
horse family
horseshoe crab
host
humpback whales and their songs
Hydra
Hymenoptera
Hyracoidea

ice worm
imago
imprinting
insect
insect senses
Insectivora
insects that bite and sting
invertebrate
isopod

jellyfish
juvenile hormone

lactation
Lagomorpha
larva
lateral line
littoral zone
lizard
locomotion
lungfish

mammal
marsupial
mating ritual
medusa
mesoglea
metamorphosis
metazoan
migration
millipede
mimicry
mite
mole (animal)
mollusc
molting
monkey
Monotremata
mosquito
mother-of-pearl
myriapod

nautilus
nekton
nematocyst
nematode
Nemertea (ribbon worms)
Neopilina
nest
nictitating membrane
notochord
nymph

ocellus
octopus
octopus eye
odonatan
oligochaete
oogonium
Ophidia (snakes)
Ophuroidea (brittlestars)
orthopteran
osmoregulation
Osteichthyes
ostrich
oviparous animal
ovipore
owl

Paedocypris
parasite
parenchyma
parthenogenesis
pearl
pedicel
pedipalps
pentadactyl limb
Perissodactyla
Phoronida
Photocorynus spiniceps
pigeons and doves
piranha
photoperiodism
placental mammals
planarian
plankton
plumule
poikilotherm
Polyplacophora (chitons)
polyp
Polypterus
primate
Proboscidea
proboscis
pronotum
prosimian
protective coloration
prothorax
protozoan
pupa

radiolarian
radula
rattlesnake
red tide
regeneration
reproduction
reptile
reptiles and amphibians, unusual
rhynchocephalia
Rodentia
rorqual whale
rostrum
ruminant

sagittal crest
scales
Schindleria brevipinguis
scorpion
sea anemone
sea cucumber
sea fan
sea pen
sea snake
sea urchin
sei whale
sepia
sessile
shark
sheep
Siphonaptera
siphuncle
Sipuncula
Sirenia
slug
snail
snakes, lizards, and turtles
solifuga
sparrow
sperm whale
spermatheca
spermatophore
spicule
spider
spinneret
spiracle
sponge
Squamata
squid
starfish
Strepsiptera
sturgeons
sucker
swim bladder

tadpole
tapeworm
Teleostei
tentacles
termite
territoriality
tetrapod
threadworm
tick
tracheae
Trematoda
tripoblastic
tuatara
tube feet
tunicate
Turbellaria
tusk shell
tymbal organ

ungulate
Urodela (newts and salamaders)

vertebrate
vestigial

whale shark

zoology
zooplankton