Stock Animal Facts

I know two things about the horse
And one of them is rather coarse.
Naomi Royde-Smith

Whenever certain animals are mentioned, works (especially educational ones) will feel the urge to say a certain fact about them. Oftentimes it's intended to sound like something surprising or fascinating, which in general it would be if you didn't hear it every time that animal was mentioned in every work. With many Seldom-Seen Species, their stock facts may be the only thing anyone (barring specialists) can ever say about them. See Somewhere This Index Is Crying if the stock "fact" about an animal is false. Can overlap with Artistic License - Biology if it is clearly false. Occasionally a victim of Science Marches On.

Can overlap with Stock Animal Diet and Stock Animal Behavior.

Note: As this trope is based on its ubiquity, the only works that should be listed are aversions, subversions, lampshaded examples, in-universe examples, and other variants.

    open/close all folders 

General Examples:

  • The giant squid has eyes the size of dinner plates. No one has seen one alive. (Until 2004.)
  • Snails leave behind a trail of slime that hardens and turns silver.
  • If a bit of sand or a stone gets inside an oyster's shell, it'll produce nacre around it and produce a pearl.

  • Earthworms can regenerate (many other invertebrates can, but earthworms are perhaps most well known for it).
    • However, the common idea that cutting an earthworm in half will result in two earthworms is basically false; it's next to impossible for the half without a brain to grow a new one.



  • Insects have six legs and are divided into three body segments.
  • There are more insects (and arthropods in general) than any other type of animal on Earth.
  • Caterpillars become butterflies through metamorphosis. (Most other insects also go through metamorphosis, but it's always butterflies.)
  • Insects can see colors that humans can't.
  • Mayflies live only a few hours after attaining their adult form (the form in which they breathe and fly in the air). Their lifespan isn't that impressively short if you count their larval stage, where they swim around a lake much like mosquito larvae. Don't expect every source that talks about the matter to be clear on this qualification.
  • Honeybees die after stinging. Somewhere, an Entomologist Is Crying if the same is said about bumblebees or wasps. Also, the death is because it can't extract itself from a sufficiently thick-skinned animal; they can still sting other bees without a problem.
  • Most bees in a hive are sterile females.
  • Bees communicate with each other with dance-like moves.
  • A queen bee starts out as a regular larva but is fed royal jelly.
  • Male bees or drones are stung to death after mating with the queen.
  • Mosquitoes are the most dangerous animals on Earth by number of deaths caused.
  • Some prehistoric dragonflies were the size of hawks.
  • Cockroaches have been around "longer than dinosaurs". If you cut a cockroach's head off it can still survive for a few days. Cockroaches are the only animal capable of surviving all-out nuclear war.
  • Ants are really strong and are some of strongest animals for their size.
  • Ant, bee, and wasp colonies have a collective mind.
  • Red ant colonies will sometimes invade black ant colonies.
  • Army ants can reduce a corpse to bones in a few hours.
  • The rhinoceros beetle is the strongest animal of its size.
  • Fleas can jump really really high for their size.
  • If this kind of insect was the size of a human, it'd be able to jump this high/lift this much/run this fast.
  • Only female mosquitos bite.
  • Female praying mantids actually bite off the male's head after mating.
  • Contrary to popular belief, a wild beehive does not resemble a hornet nest.


  • Spiders are not insects, they're arachnids because they have EIGHT LEGS (well, there's more to it than that, but very simplistic differences are often pointed out).
  • Spiderwebs are incredibly strong.
  • Spiders don't eat their prey but suck its bodily fluids.
  • Spiders die shortly after laying their eggs.
  • Tarantulas are not actually all that dangerous.
  • Scorpions glow in the dark under a blacklight.
  • Black widow spiders are so-called because the more venomous female kills the male after mating.


  • Fish are vertebrates with gills.

Cartilaginous fish

  • You're more likely to be killed by lightning/bees/cars/coconuts than to be killed by a shark.
  • Sharks have been around "longer than dinosaurs". Technically true, but they haven't "remained unchanged" as many would have you think.
    • Cladoselache was the first shark.
  • The whale shark is the largest living fish, but eats only plankton.
    • The basking shark is the second largest.
  • No one knows what the oddly shaped head of hammerhead sharks is used for (which is actually not true).
  • Tiger sharks can eat ANYTHING.
  • Sharks frequently lose their teeth, which are always replaced by new ones growing in.
  • Sharks must keep moving or they'll die (not true for wobbegongs, nurse sharks, whitetip reef sharks, etc).
  • Unborn sand tiger sharks will sometimes eat their weaker siblings while still in the womb.
  • Bull sharks can survive in freshwater.
  • The megamouth shark was discovered in 1976 and has only been seen a few times since.

Bony fish

  • Coelacanths are "living fossils". (They were thought long extinct until a live one was caught in 1938.)
  • Salmon hatch, swim to the sea, return to their birthplace by leaping up some waterfalls while trying to avoid bears, spawn, then die.
  • Flounders are so good at changing color they can blend into a chessboard.
  • A number of people die from eating fugu every year.
  • Electric eels are not really eels, but instead a species of knifefish.
  • Male clownfish actually turn female if the dominant female dies. They live in sea anemones.
  • Male seahorses incubate fertilized eggs in a special pouch and give birth. (They do not care for the young afterwards, however).
  • A Siamese fighting fish will attack its own reflection.
  • The growth of a goldfish is determined by the size of its environment.
  • Male anglerfish are much smaller than the females. Their adult life consists of finding a female, latching on to her like a parasite, and essentially merging with her, becoming nothing more than a handy source of sperm.

  • Amphibians have slimy skin and can "live on both land and water". (Not strictly true in the case of wholly aquatic amphibian species.)

Salamanders and kin

  • Axolotls never grow up. They do get bigger, but they retain a juvenile form (just picture an adult-sized baby).

Frogs and toads

  • Tadpoles become frogs through metamorphosis. (Other amphibians also go through metamorphosis, but it's always frogs.) The only exception is the coqui and its relatives.
  • Frogs have slimy skin and leap. Toads have bumpy skin and hop. (Not always true, and technically it's more a matter of toads vs. other frogs, as toads are just a specialized clade of frogs.)
  • Poison-dart frogs have really deadly poison. Their bright colors warn predators to stay away. South American native tribes use their poison for hunting.
  • The cane toad is causing lots of problems in Australia.
  • The Pacific tree frog is the only frog species that actually says "ribbit."
  • The pipa toad incubates its young in its back.

  • Reptiles have dry scaly skin, are "cold blooded" (more technically, ectothermic), and lay eggs on land. (Unless you're using cladistics, in which case birds are also a specialized clade of reptiles. Not to mention that many extinct animals traditionally thought to be "reptiles" were almost certainly to some degree warm blooded.) Despite what the description of herpetology might tell you, amphibians are not reptiles, and vice versa. Reptiles are amniotes, along with mammals and birds.

Turtles, tortoises, and kin

  • You can't take a turtle out of its shell (unless you intend to rip out its ribcage and a big chunk of its backbone).
  • The leatherback turtle is the largest of all sea turtles.
    • The Galapagos tortoise is the second-largest turtle, and the largest on land.
  • Most baby sea turtles (hatched on the beach) are eaten by birds before they can reach the sea.
  • A turtle flipped on its back cannot right itself and will eventually die. (Although this happens occasionally, most turtles are actually quite capable of righting themselves.)
  • Tortoises can live well over one hundred years.

Snakes, lizards, and kin

  • Various strange lizard defenses get a lot of attention (often the only attention these lizards will get):
    • Basilisk lizards can run on water.
    • Horned lizards spray blood from their eyes.
    • Many lizards can drop their tails as a distraction and regrow it later.
    • Blue-tongued skinks scare off predators using their blue tongues.
    • The frilled lizard spreads its frill to scare predators.
  • Constrictor snakes and pythons aren't venomous, they suffocate their prey.
    • The reticulated python and the anaconda are the longest and largest snake, respectively.
  • Various legless lizards aren't actually snakes.
  • The king cobra is the largest venomous snake.
  • Chameleons change color and can see in two different directions at once. They will turn white if they get startled.
  • Geckos can climb vertical surfaces.
  • This much venom from some kind of venomous snake is deadly enough to kill a huge number of people/mice.
  • The Komodo dragon is the largest living lizard. It has deadly bacteria in its mouth it can use to kill prey. (It is now known that it relies more on shock and blood loss. Also, it has actual venom in its saliva, not just bacteria.)
    • The Gila monster and beaded lizard are the only venomous lizards. Again, Science Marches On.
  • Non-venomous milk snakes and king snakes mimic venomous coral snakes.
    • Red on yellow kills a fellow, red on black won't hurt Jack.
  • Tuataras look like lizards, but they're not. They have three eyes. They're only found in New Zealand.
  • Mosasaurs were not dinosaurs.
  • Whiptail lizards are all female.
  • The marine iguana is the only marine lizard (as long as you don't count snakes).


  • Crocodiles have long narrow snouts, alligators have broader ones.
  • Most crocodilians are able to take down HUGE prey with ease in the water. (The gharial is more or less stuck with fish.)
  • A human can hold a crocodile's jaws shut without much effort, because the jaw muscles that open crocodile jaws are much weaker than those that close them.
  • Crocodilians have four-chambered hearts like mammals and birds, and some of their ancestors were likely warm-blooded (or endothermic, if you prefer)
  • Birds are their closest living relatives, as the two are the last remaining archosaur clades. It may sound strange, but they share more in common than with any other living reptile or mammal.
  • The Florida Everglades is the only place where crocodiles and alligators coexist in the wild (untrue if you count caimans as alligators).


  • Dinosaurs are reptiles with an erect stance and "couldn't swim or fly". (The latter is clearly false now that we know birds are dinosaurs, and even some traditionally non-bird dinosaurs are now known to have been capable of flying or swimming. The swimming thing is particularly ridiculous considering that most land animals can still swim, even if they aren't specialized for it or dislike getting wet.) "Dinosaur" means "terrible lizard" (though the intended meaning was actually "fearfully great lizard").
  • We can't know what colors (prehistoric) dinosaurs were. This is no longer the case, at least for some well-preserved specimens.
  • No one knows exactly how (non-bird) dinosaurs became extinct. (In fact the K-Pg extinction is really one of the better understood mass extinctions.) They were probably killed by an asteroid impact.
  • There is a big debate about whether Tyrannosaurus is a scavenger or predator. This is actually an exaggeration as well as a false dichotomy, as only one recent researcher has endorsed the idea that Tyrannosaurus was an obligate scavenger and has now appeared to have abandoned this viewnote , while everyone else pretty much agrees that Tyrannosaurus would have been both a scavenger and a predator as the vast majority of land carnivores are today.
    • Tyrannosaurus was the biggest carnivorous dinosaur. Now a victim of Science Marches On—the South American Giganotosaurus and North African Carcharodontosaurus and Spinosaurus were bigger in both length and mass.
  • Oviraptor was thought to have been a specialist egg eater until it was found that the nest it was preserved on was its own, and that it was actually brooding its own nest.
    • This discovery led to the popularity of the stock factoid that these dinosaurs were "good mothers", until the brooding specimens of Oviraptor were discovered to lack female-only medullary bone, indicating that they were in fact good fathers.
  • Deinonychus may have hunted in packs.
  • Sauropods/Stegosaurus had brains the size of a golf ball/walnut. They had a "second brain" in their hip region. (The second one isn't true.)
  • Ankylosaurids could break the ankles of predators with their tail clubs.
  • Sauropods were really really big. They were the largest dinosaurs, and the largest land animals ever.
  • Giganotosaurus was larger than T. rex (debatable).
  • "Brontosaurus" is a junior synonym of Apatosaurus. As of 2015, this is no longer true.
  • Megalosaurus & Iguanodon were the first (non-bird) dinosaurs named.
  • Spinosaurus, whose holotype was lost in World War II, had a huge sail on its back.
  • Dilophosaurus (originally considered a species of Megalosaurus) had two crests but not a frill or venom.
  • Stegosaurus used its plates for display or controlling its body temperature.
  • Troodon was the smartest (non-bird) dinosaur. If it survived to the present, it would develop a humanoid form (ludicrously improbable).
  • Microraptor had four wings.
  • Allosaurus was an early relative of Tyrannosaurus (untrue beyond them both being avetheropods).
  • Maiasaura cared for its young.
  • Ceratosaurus had a horn on its nose and a row of scutes on its back.
  • Micropachycephalosaurus had the longest name of any dinosaur.
  • Cryolophosaurus, the first Mesozoic dinosaur named from Antarctica, was originally called "Elvisaurus" after the crest on its head.
  • Deinocheirus is known only from a pair of giant arms. No one knows what the whole animal looked like (as of 2014, this is no longer true).

Other reptiles

  • Pterosaurs, plesiosaurs, and ichthyosaurs were not dinosaurs. Nor was Dimetrodon, which is more closely related to mammals.
  • When it was first described, Elasmosaurus' skull was placed at the end of its tail, starting the famous Bone Wars.
  • The largest pterosaurs (like Quetzalcoatlus) were as large as a small airplane.
  • Pteranodon had a large crest on its head. It was thought to have been a rudder to help steer in flight, but it is now believed to have been part of a mating display.
  • Pterosaurs were the only reptiles capable of true flight (probably untrue depending on how many non-avian dinosaurs were capable of true flight).

  • Birds have feathers, wings, and beaks, and most can fly. (In reality this applies more to modern birds, as many extinct birds lacked beaks. Also, many dinosaurs traditionally considered non-avian also had feathers and wings, and some may have even been able to fly.)
  • Male birds often have brighter plumage than females, the better to attract a mate. The females' drabber coloring allows her to blend in more with her environment, allowing her to better protect her young.
  • The peregrine falcon is the fastest animal on Earth (in a dive).
    • The spine-tailed swift is the fastest flying bird in level flight.
  • The ostrich is the largest living bird and lays the largest eggs of any living animal. No, it doesn't stick its head in the sand to avoid danger, instead it crouches close to the ground or runs. It can run really fast, and can kill a lion with a kick. Its eyes are actually larger than its brain and are the largest of any land animal.
  • Cassowaries can kill you with a kick.
  • Honeyguides guide honey badgers to honey. Which is not actually true (or at least, has not actually been recorded).
  • Owls have really good hearing and can fly silently.
    • They can turn their heads very far around.
    • They regurgitate the fur, bones and other indigestible parts of their prey as "furballs" (often implied to be unique to owls, but this is false).
    • They fly at night, whereas other birds of prey (traditionally called "falconiforms") hunt during the day (it's not that simple).
  • Hummingbirds can fly backwards and hover in midair.
  • The bee hummingbird is the smallest bird.
  • Galapagos finches inspired Darwin's theory of evolution. (Actually, Galapagos mockingbirds had a bigger influence.)
  • Vultures have bald heads because they eat messy food. This might not be entirely true.
    • Vultures will circle a dying animal, biding their time before the banquet.
    • American vultures are more closely related to storks than to other raptors (very likely false).
  • The emu is the SECOND largest bird in the world (questionable).
  • Elephant birds laid the biggest eggs ever.
  • The harpy eagle eats monkeys and sloths. Its feet are the size of a man's hand.
  • The young hoatzin can use its wing claws to climb trees. The fact it retains wing claws is also often said to be unusual for modern birds, but this is erroneous.
  • Flamingos get their pink color from the microscopic crustaceans they eat. (This is actually the case for many brightly colored birds, though usually it's fruit or insects they eat instead.)
    • Flamingos resemble both storks and geese, resulting in confusion surrounding their relationships (Science Marches On, as molecular analyses unanimously unite them with grebes).
  • Parrots and crows are the smartest birds. They can mimic sounds (particularly human speech).
  • Parrots are the longest-living bird.
  • Archaeopteryx was the "first bird"... though this depends on its phylogenetic position and exactly what you call a bird.
  • Pigeons mate for life, and males help females raise their young.
    • Baby pigeons eat "pigeon milk" regurgitated by their parents.
    • Prior to its extinction in 1914, the passenger pigeon was the most common bird in North America.
  • Mandarin ducks will stop loving each other once their nest is built.
  • A canary will never find a mate if it cannot sing.
    • Only male canaries sing.
  • Male penguins court females by offering them pebbles.
  • If frightened, a peacock will shed its distinctive tail feathers. (True, although the phenomenon of fright molt or schreckmauser is by no means unique to peacocks.)
  • Shrikes impale their prey on thorns.
  • The Egyptian plover feeds on scraps found in crocodilian mouths (very likely untrue).
  • The pitohui is the only poisonous bird. A few other birds have since been discovered to be poisonous, and several more can sequester toxins in their flesh.

  • Mammals have hair or fur and nurse their young with milk. Most don't lay eggs. (Not so with Mesozoic mammals, most of which were probably egg layers.)
  • In many species males will fight one another for the privilege of mating with a particular female.
  • Male mammals tend to be more aggressive than female mammals unless her young are threatened.
  • The extinction of (non-bird) dinosaurs paved the way for mammals to "dominate".


  • There are only one/two/three/five living egg-laying mammals. (In terms of species, five is the correct number, but many works will lump all the echidnas into the same category, or at most make a distinction between long-beaked echidnas and the short-beaked echidna.)
    • The duck-billed platypus is one of the few living mammals that lay eggs. It also looks like a Mix-and-Match Critter. Males are venomous. They were originally thought to be a hoax.
    • Echidnas are the only other living mammals that lay eggs.


  • Marsupials are mammals with pouches (though some species have lost their pouches).
  • Most modern maruspials are found only in Australia. (The fact that South America actually has a lot of other marsupials as well is almost never mentioned. Some works even claim that the Virginia opossum is the only non-Australian marsupial.)
  • Marsupials are slower-moving, less intelligent and more "primitive" than placental mammals, which is why they eventually went extinct in most parts of the world.
  • Opossums play dead. (Technically untrue if it's implied to be a deliberate action, as it's more of a reflex.) More specifically, it's the Virginia opossum that does this, but many works don't specify that. They are the only marsupials that live in America.
    • Opossums have prehensile tails. They're also idiots, as they have a small, simpler brain.
  • Koalas are not bears. And they eat eucalyptus leaves to get moisture. Also, they only eat eucalyptus leaves. If they eat enough eucapyptus they will get stoned and fall out of trees. Their appendixes are twice as long as their bodies.
    • Parodied/subverted in an Olde English sketch, a Nature Mockumentary called "I Hate Nature". "Everyone knows that koalas eat eucalyptus leaves, but few people know why. The reason is that koalas are boring and they suck. No imagination."
  • Wombats have backward-facing pouches so they don't get soiled while burrowing.
  • The yapok is the only semi-aquatic marsupial. It can close its pouch to stop water from entering.

Non-cetacean ungulates

  • The pronghorn is the second fastest land animal, and has more endurance than the cheetah.
  • The hippo is the most dangerous mammal in Africa. It secretes a fluid from its skin that looks like blood.
  • No one knows what zebra stripes are for, but likely to be camouflage. No two zebras have the exact same stripes.
  • A camel can survive for days without drinking
    • A camel's hump is filled with fat, not water. The metabolism of fatty acids produces a large quantity of water, which is what allows a camel to survive for so long without dying from dehydration.
  • The giraffe is the tallest living animal.
  • Pigs aren't actually dirty animals, and are really quite intelligent.
  • Rhinos have bad eyesight.
    • The white rhinoceros was named because the Dutch word for "wide" (referring to its broad lips) was confused with "white" (probably not true).


  • Whales are mammals, not fish.
  • The blue whale is the largest animal ever, bigger than even the largest dinosaurs.
    • The fin whale is the second largest animal ever.
  • Whale vomit or ambergris is used to make perfume.
  • Whales live in groups called pods.
  • Whales will push a sick member of its pod to the surface so it can breathe.
  • Whales communicate by "singing."
  • Whales eat plankton (true only of baleen whales).
  • Dolphins have been known to save drowning humans.
  • Dolphins can kill sharks by butting them in the abdomen.
  • The orca is the largest dolphin.


  • The cheetah is the fastest land animal. It can go as fast as a car on a highway.
  • The honey badger is badass.
    • The wolverine is badass and can chase off much larger predators.
  • The tiger is the largest big cat, and one of the few which like water. It doesn't live in Africa.
    • The jaguar is the other big cat that likes water. It also doesn't live in Africa.
  • Mongooses can fight and kill venomous snakes (usually cobras). Some savvier works will also point out that snakes aren't that much of a mongoose's diet though.
  • Hyenas aren't dogs, or pure scavengers. Their jaws can break bone. The females are dominant and have masculinized genitalia.
  • Older books will claim that the giant panda is not a bear, but closer to raccoons. We now know it is indeed a bear. It only eats bamboo. (Technically, it'll sometimes eat meat as well.) It is also one of the few non-primate mammals that has opposable thumbs, or at least close enough to that.
  • If you see a cougar, back away slowly and don't try to run. The cougar is known by many names (such as mountain lion and puma).
  • The polar bear is the largest bear and non-pinniped carnivoran, and is also the most predatory bear. It actually has black skin and transparent fur.
  • Next to polar bears, grizzlies are the most dangerous.
  • Bears are unlikely to attack humans unless they are mother bears accompanied by cubs.
  • Bears hiberate during the winter months (although it's debated if this is true hibernation or not).
    • Bears are apt to be irritable and dangerous if you run into in the spring right after they have woken up, without having eaten in months.
  • Bears hate loud noises and can be scared off by shouting or a clanging bell.
  • Lions are the only social felid. Males kill the cubs when they take over a pride.
  • Female lions do most of the hunting.
  • Domestic cats will tease and torment their prey before killing it. (This is probably just an instinctive response to movement).
  • Raccoons are highly intelligent and will figure out any lock you put on your garbage bins. This has allowed them to thrive in urban environments
  • Crabeater seals don't actually eat crabs.
  • Binturongs, also known as bearcats, smell like fresh-buttered popcorn.
  • Leopards drag kills up trees.

Rodents and Rabbits

  • If rodents and rabbits don't have something to gnaw on, their teeth will grow indefinitely.
  • Flying squirrels don't fly, they glide.
  • Squirrels bury nuts throughout the fall so they will survive the winter. They often forget where the nuts are, however, and many trees get their start this way.
  • Porcupines don't shoot their quills. They aren't closely related to hedgehogs.
  • Kangaroo rats don't need to drink water, they get it all from their food.
  • Rats are highly intelligent and can learn to avoid virtually any trap.
  • Rats have toxic urine. (Not true if the rat has no diseases.)
  • Rabbits are not really rodents.
  • Hares are bigger than rabbits.
  • Rabbits wrecked havoc on the Australian environment because they have no natural predators.


  • Galagoes, lemurs and lorises are the "earliest" and most "primitive" primates.
  • Lemurs are found only in Madagascar.
  • Bush babies' enormous eyes allow them to see at night.
  • Monkeys have tails, apes don't.
  • Chimpanzees are the closest living relatives to humans. They know how to use tools.
    • Chimpanzees are very aggressive as adults. Male chimps will slaughter their rivals' babies.
  • Gorillas aren't actually all that aggressive.
  • Howler monkeys are really, really loud.
  • Orangutans are the largest arboreal animals
  • Bonobos are the hippies of the primate world. They are cooperative, non-combative and very highly sexed.
  • Apes can learn sign language (heavily debated).
  • Man is a mammal (and a primate).

Other mammals

  • Bats are the only flying mammals. And they aren't blind, but most species do rely mostly on echolocation to find their way in the dark. Only a few species drink blood. They also don't fly into your hair. (In actuality, almost NO megabats aka fruit bats rely on echolocation, mostly because they are active during the day or mornings and evenings and use their well-developed eyesight instead of relying on sound.)
  • Hyraxes are closely related to elephants.
  • Elephants (specifically, the African elephant) are the largest land mammals. They are also the only quadrupeds that cannot jump.
    • They are the only quadruped that cannot jump, excluding rhinos, hippos, sloths, tortoises...and in Nairobi there is an elephant jumping festival that implies that African elephants at least can jump.
  • Pangolins are the only mammals with scales.

Exceptions, Subversions, Aversions, and Notable Examples in Media:

Web Original

Western Animation

Real Life
  • That black widow fact is only half true. She will eat him if he sticks around to mooch off her web. Or, well, if they've been locked in a box for science.

Alternative Title(s):

Stock Animal Fact