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"Well, let's just say that I could write a hell of a paper on a grown man who dresses like a flying rodent."

"Bats aren't rodents, Dr. Meridian."
Dr. Chase Meridian and Batman, Batman Forever

Most writers are mammals, yet we still get some things wrong with mammals.

One of the most Egregious examples is mistaking cetaceans (whales, dolphins, and porpoises) for fish. There's also those who insist that orcas, or killer whales, are just whales and not dolphins as well. Orcas are dolphins, which are toothed whales, so people are right about them being whales, but wrong about them not being dolphins.

Another example is the fact that many people mistake kinkajous for primates. Kinkajous are not primates, but a member of the raccoon family within the order Carnivora. There are also a lot of mammals are mistaken for rodents, including weasels (in Carnivora), rabbits, hares, and pikas (order Lagomorpha), shrews and moles (order Soricomorpha), and hedgehogs and moonrats (order Erinaceomorpha).

People also draw male kangaroos with pouches. The only extant (still existing) marsupial with both sexes having a pouch is the yapok, a semi-aquatic opossum native to South America. The Thylacine, or Tasmanian Tiger, exhibited this trait too, but it is now extinct. Rabbits are often drawn with paw pads, which they don't have in Real Life. Also, rodents and lagomorphs do not have canine teeth. Another example includes elephants drinking with their trunks instead of sucking up the liquid with their trunks and then squirting it into their mouths, like real elephants.

Another example is to refer to saber toothed cats, mammoths, and other Pleistocene megafauna as dinosaurs just because they are fierce and extinct and/or portraying them as being around during the Mesozoic era. Saber toothed cats are prehistoric cats that lived during the Pleistocine.

And don't forget that humans are NOT descended from monkeys. We're descended from apes. And we still are apes. Great Apes, to be specific.

Nothing to do with breasts. Yes, all mammals have mammary glands for, well, obvious reasons, but it's not the focus here.

Subtrope of You Fail Biology Forever. Supertrope of Kangaroo Pouch Ride and Somewhere an Equestrian Is Crying.



  • In an H2OH commercial, the narrator voice comments how cool it is that nature gave spikes to the hedgehog, instead of you (human). In the video, though, the guy shoots spikes all around. It's said that porcupines can shoot their quills -- porcupines are not hedgehogs, however, and the popular belief is in fact false. Porcupines may have their spines dislodged while swinging their tails around because the spines are very loosely attached to the porcupine so that they'll come out once they've been lodged in another creature's skin; however, they don't deliberately shoot their quills at a target. They're much more likely to reverse into your leg and fill it with hooked barbs.
  • An ad for Napa auto parts features a hunter crouched in the marsh with his gun and, instead of a regular hunting dog, he has a fluffy white poodle with a pink bow in its hair. The tag line is, "Having the wrong auto part makes even less sense." This is absolutely hilarious to anyone who knows that poodles were bred to be wetland hunting dogs, and the dog doesn't care if it's white, fluffy, and wearing a ribbon: when there's a bird to be retrieved, it will be retrieved, no matter the amount of mud involved. Also, those ribbons and poofs and whatnot that look so fancy are all relics of their hunting days - the ribbons were color-coded to their owners, and those poofs were originally for the purpose of keeping the dog's hair out of its eyes.


  • Before The Fairman Rogers Four-in-Hand painted between 1879-80, the artists drew horses with highly unrealistic gaits.

Comic Books

  • In the manga "Saber Tiger," by Hoshino Yukinobu, the narrator says "despite its name, the saber-toothed tiger was actually the ancestor of the lion," and not tigers. Of course, even a superficial round of research would reveal that lions and tigers, and by extension, leopards, jaguars and house cats, are more closely related to each other than any of them are to saber-tooths.
    • Later, time travelers pontify about how the mammoths are/were doomed because there was an evolutionary trend for the tusk tips to overlap. Of course, nevermind that mammoths did not use the tips of their tusks for food gathering, nevermind that only the adult males had the massive tusks (females and subadult males having much more modest tusks), and nevermind that there were already two rather successful species of mammoths (the Columbian and Imperial) in North America with tusks that had overlapping tips. Also counts as a Dan Browned , given as how a review boasts how the manga was a great example of "hard science fiction."
  • Gorilla Grodd, a supervillian from the DC Universe who is a, shock, gorilla, is frequently shown eating people, especially when Grant Morrison is writing him. Gorillas are actually herbivores, and while super-intelligent telepathic gorillas mutated by aliens may be different, Grodd's certainly the sort of person to eat someone For the Evulz even if he'd have trouble digesting them.
  • Bats are not rodents, something that most Batman writers apparently don't know. It's Lampshaded sometimes.


  • Monstro from Disney's Pinocchio is a sperm whale with upper teeth and lines on his belly. Real sperm whales only have lower teeth and do not have lines on their belly, since belly lines only appear on baleen whales, and sperm whales are toothed wales.
  • There is a young anteater in Ice Age 2: The Meltdown, who has a mouth at the base of his/her elongated snout. Real anteaters have tiny mouths that are located at the tips of their snouts, not underneath them.
  • In Ratatouille, Remy, a rat, gags when he smells Linguini's soup. Rats are physically incapable of vomiting, so either the writers didn't know this, ignored it for the gag, or the soup is really that bad.
    • Possibly justified, as gagging is a different reflex from vomiting. Gagging is an anti-choking defense, while vomiting is mainly an anti-poisoning defense.
  • Its funny that they make fun of the "apes mistaken for monkeys" thing in the Planet of the Apes remake, but played straight in that to make them seem more attractive, the female apes were given eyebrows, something real apes do not have, and human-sized breasts, evident when the female ape is being "sexy" for the Senator Nado.
  • In The Legend Of The Titanic, dolphins can jump as high as Titanic decks and even fly for a short amount of time by flapping their fins. It should be obvious to anyone with any grasp of biology -- or hell, logic -- why this doesn't work.
  • In Ace Ventura: Pet Detective, Ace has a phobia of bats (one of the few animals he's not friendly with) and often calls them "rats with wings". However, this is more likely to be a derogatory term rather than an actual fact.
  • In Gremlins 2, one of the scientist twins who find Gizmo describes him as a rodent. Even though it's not clear what he is, any biologist examining him would assume he was some kind of lower primate, similar to a tarsier.
  • In Indiana Jones and the Temple of Doom, Indy identifies the large winged creatures flying overhead as "giant vampire bats". Vampire bats are indigenous to South America, not India; given their size and the fact they're flying in broad daylight, the animals in question are almost certainly harmless fruit-eaters. Possibly Indy was just yanking Willie's chain.
    • Giant vampire bats are real creatures, but they've been extinct for tens of millions of years.
  • Fern Gully has one. Batty's wings keep changing from one free claw with four fingers supporting the wings, to one free claw with one finger holding the wing, or the complete opposite of Ptero-Soarer: three or four free claws with one finger holding the wing. Most obvious in the rap.
  • The original Planet of the Apes films have gorillas as the violent, militaristic apes. But in reality, chimps are known to be much more violent than gorillas. Probably a case of Science Marches On, as gorillas were often depicted as violent in the past. Also probably why the 2001 version had a chimp as the main antagonist.


  • Mariel of Redwall, from Redwall series, mentions Gabool the Wild having gold "replacements" for his canine teeth. This fails biology because he is a rat, and all rodents do not have canine teeth to begin with.
  • In the books, movie, and PBS kids TV show, Curious George is referred to as a monkey even though he is really a chimpanzee.
  • In Prince Caspian, Reepicheep the talking mouse has lost his tail in battle, and he argues with Aslan over whether it needs to be regrown. Both of them seem to think a mouse's tail has no practical value, and is of use only as a badge of honor or vanity, but the tails of mice and rats are actually important thermoregulatory structures, without which he'd be quite vulnerable to heat stroke. This is more likely Science Marches On, rather than a failure on C. S. Lewis's part. Research on thermoregulation in rodents was not common knowledge in 1950-51, when the earliest reference to it was published in 1958. It makes even less sense in Reepicheep's case since wielding a sword would probably be much easier with a tail to balance with.
  • Kim Harrison persistently seems to think ferrets are rodents in a couple of her books about The Hollows.
  • Averted in the Discworld. Don't call the Librarian a monkey. It makes him displeased. Remember "Do not meddle in the affairs of wizards, especially simian ones. They aren't that subtle." Also played straight since all wizards are simians... unless they've turned themselves into something else, which the Librarian did, during The Lost Continent.
    • Granny Weatherwax once Bowdlerized a summary of Nanny Ogg's favorite song as being about "a rodent that can't be persuaded to be bothered by anything". The actual song title is "The Hedgehog Can Never Be Buggered At All", and hedgehogs are members of the insectivore order, not rodents.
  • According to his backstory from James and the Giant Peach, James Henry Trotter's parents were eaten alive by an escaped zoo rhinoceros. In real life, rhinos are supposed to be herbivores. Fortunately, the book lampshades this as being very strange behaviour for a rhino, and the film adaptation averts it by changing said rhino from an actual rhinoceros to a large rhinoceros-shaped demon made entirely out of thunderclouds.
  • In Domain, a horror novel about giant killer rats, one of these aggressive rodents gets stuck twice -- once by its shoulders, again by its hips -- while squeezing its body through a gnawed hole in a door. Any exterminator, or any rat-fancier who's ever tried in vain to put a collar on one, knows that real rats can fit their entire bodies through any opening large enough for their heads.
  • ETA Hoffmann describes dolphins as having scales in The Nutcracker and The Mouse King and has them blowing water through their nostrils. (Dolphins have a single blowhole on the top of their head, and they don't actually blow water out through it.)


  • As pointed out on QI, Dogs don't do it Doggy Style: Due to the coupling knot, they should be depicted tail-to-tail facing away from each other during climax.
  • Many Furry Fandom artists who draw cats draw them with torsos that taper toward the hind legs like dog torsos. Cheetahs may have torsos that look a bit like that, but other cats have more or less parallel torsos.
    • There is also a slight tendency for some (but by no means all) Furry artists to presume that all mammals go about... certain activates… in ways similar to either Humans or Dogs, or at least how some people presume dogs to go about them (see above). Then again, an Acceptable Break From Reality as when did Rule 34 care about anatomical correctness even when it was just humans involved?
  • Any Christmas movie or TV special that shows female reindeer without antlers, or male reindeer retaining their antlers into December, Fails Biology Forever. Females of the species need antlers to guard their young from predators, whereas males shed theirs after the rutting season, with one exception: males retain antlers in winter if they have a "special operation". Older Christmas specials tend to show extremely dainty brown deer that don't resemble reindeer at all.
  • Several works by Dingo Pictures primarily feature a raccoon character that for some reason moved like a kangaroo!
  • Many a work have depicted Ferrets as being wild animals; even a few places where Ferrets are illegal have made this mistake, much to Ferret owners dismay. Ferrets, the pet animal, are a domesticated series that can't live long in the wild, and have been domesticated at least since Ancient Egypt. As such a domesticated ferret will actually die extremely quickly in the wild, which some ferret owners unfortunately forget when they "release" them into the wild if they get tired of the ferret. It may be mix-up with the wild black-footed ferret which Ferrets resemble, because they look like wild weasels.
  • The urban legend of the "Mexican pet" loses any veneer of plausibility to anyone who has ever seen a rat up close, or knows anything about their behavior. Even an extremely near-sighted tourist would've surely caught on that an animal with grasping toes on all four feet, that climbs things, can't possibly be a dog.
  • Angel: In the episode "Through the Looking Glass", the gang is discussing the picture of a male red deer. Had Wesley simply used the term "hart" or "stag" in the layman fashion (to refer to any male red deer regardless of its age), it might not have been accurate but it wouldn't have been comment-worthy. Unfortunately, he goes into detail saying a hart is "a male red deer or staggard" indicating the script-writers may have attempted to research the proper naming convention that exists for male red deer (that or they thought a "stag" and "staggard" meant the same thing). A staggard is a male red deer in its fourth year of life. A stag is a male red deer in its fifth year of life. A hart is a male red deer over five years old (i.e., in its sixth year of life). The picture itself shows a 10-point deer (5 tines on each antler) which is a "great hart" (a stag over six years old, i.e., seven years old or older with 10-16 tines). By using generalised layman terms, it all could have been handwaved as an ordinary conversation or at least the "hart" being a contraction of "great hart" where the picture itself was concerned. The attempt to be clever by referring to "staggard" simply emphasised the writers had failed to do their research.

Tabletop Games

  • The Ravenloft darklord Urik von Kharkov, a panther-form shapeshifter, is described as acquiring slitted pupils like a cat's when he loses his temper. But Kharkov's feline form is a leopard, one of the big cats, and their pupils are oval rather than slitted.


  • A weasel-like Beanie Baby named Runner has mustelidae officially listed as its species. The poem suggests that it could be "a ferret, mongoose, weasel or mink." Although the other three species are legitimately mustelidae, mongoose are kind of on their own classification-wise, and are actually more closely related to felines and hyenas than anything else. This research lapse may have something to do with the "mean poem" that the toy was originally released with (itself a Crowning Moment of Funny for the franchise), which identified it as a mongoose.
    • Seaweed the Otter is depicted with seaweed in her paws, as if she were eating it. Sea otters eat largely eat marine invertebrates and fish.

Video Games

  • The wolf mounts in World of Warcraft have giant saber canines in their lower jaws, which real wolves do not have. Many (though not all) cats in the game have saber-teeth, which only a single group of cats every actually had. Certain skeletal horse mounts have horns, although it might just be an aesthetic addition.
    • The devs don't know how horses run (the game animates them the same way as a cheetah, with legs outstretched in the suspension phase instead of collected). In the current version, this has been changed.
    • Elekk (a pseudo elephant mount) freakin' gallop. Come to think of it, so do the mammoths. Knee joints of adamantium! This was also eventually corrected so they run like actual elephants.
    • The wolf mounts, and by extension all wolf mobs using the worg model run nothing like an actual wolf would run. Wolf mobs using the alternative wolf model run pretty much properly.
    • Orcas apparently produce humpback whale song. When fighting, no less.
  • Donkey Kong:
    • Diddy Kong is often called a chimpanzee (and, in some instances, referred to as Donkey Kong's nephew), even though he has a tail.
    • In fact, the Kongs themselves. Having the same last name implies they're more or less related, despite them being very different species of apes and monkeys. Cross-species adoption, maybe?
    • Worse, Cranky Kong is explicitly the original DK from the arcade game. He was a gorilla then. He's currently somewhere between Chimp and Baboon, with a demonstrably different bone structure, body shape, set of limb proportions, and cranial shape. Miniature Senior Citizens as applied to non-human primates?
    • For that matter, they're nearly all colored brown, one color nonhuman apes DON'T come in.
  • Ape Escape:
    • Pretty much okay as a title for the game, yet everyone seems to call the titular primates monkeys.
      • The original title was "saru getchu"; Saru meaning monkey.
  • Knuckles looks nothing like an echidna. Not even remotely. Few Sonic characters resemble the animals they are based on, with Tails being the closest to looking like an actual fox (barring the two tails, of course)
    • The Western cartoons also had Dr. Robotnik derisively call Sonic a "rodent", which hedgehogs are not.

Web Comics

  • In Off White, a conversation between Othala and Raigho suggests that a female wolf leading a pack is unusual. In reality, wolf packs has two leaders (called alphas), and the female alpha is more likely to be dominate over the male alpha than vice versa.
    • The pack is shown hunting a bull elk. This is (possible but) unlikely because wolves, like most predators, usually target the sick, the young, the weak and anything else less hard to catch then a healthy adult animal.
    • Iki and a raven has Blue Eyes, while another raven has Red Eyes, mostly [1] unnatural colors for those animals. This is intentional, it indicates the color of their spirits.
  • In The Black Blood Alliance, Most of the wolves have body proportions that look too thin for gray wolves, let alone dire wolves.
    • Also, a real Saber-toothed cat probably would of broken its sabers off if it tried to use them the way the ones in the comic do.
    • The Blackbloods being able to survive on bats in a oasis in the desert may qualify as this.

Web Original

  • The flash clip Dugong begins with words 'Dugong, dugong it's a cow of the se-e-e-a. Dugong, dugong, also known as the manatee'. The problem is that dugong (Dugong dugong) and manatees (genus Trichechus) are different animals. Furthermore, the song contains the phrase 'Compared to dolphin, its very close cousin...'. Dugong and dolphins are water mammals, but they belong to different orders (dugong to Sirenia, dolphins to Cetacea). Hardly 'very close cousins'. Manatees and dugongs (order Sirenia) are more closely related to elephants and aardvarks than to dolphins, while cetaceans are closer to hippopotami and swine.
  • The "Dramatic Chipmunk" is actually a prairie dog.
  • This customer from Not Always Right, who believes that chickens are mammals because they "have meat."

Western Animation

  • In one episode of Phineas and Ferb, someone pitches ideas for an "inaction figure" based on Perry the Platypus, one of which is "The Mad Marauding Marsupial of Death." Right continent, wrong order. The platypus is a monotreme, not a marsupial. Ferb also once stated that the platypus is the only mammal that lays eggs; this is inaccurate, as the Echidna also lays eggs.
    • In another, Candace calls Perry Phineas's stupid rodent pet. Rodents have teeth, while platypi do not. Granted, this one can probably be chalked up to merely being an insult.
  • Yin Yang Yo had at least one episode where Yin and/or Yang throw up. However, since Yin and Yang are rabbits, they shouldn't be able to barf.
  • In one King of the Hill episode, when Bobby gets a summer job for a guy who cleans poop off lawns, he and his employer gross out his folks by describing an incident at work: their discovery of deposits of gigantic turds, scattered all over an estate's grounds. Turns out it was alpaca poo, as a neighbor's damaged fence had let a whole herd go trespassing ... and it also turns out that the writers chose the worst possible animal to blame it on, as alpacas produce lots of tiny "beans" of dung, and herds of them do so all in one place. Obscure, but a single phone call to a petting zoo could've rectified this one.
  • Barnyard treats cows and bulls as entirely separate species -- the main character is a male cow with udders (in the video game adaptation he squirts what the devs probably wish you thought was milk), while udderless bulls have also appeared.
  • Somewhat averted, surprisingly enough, in My Little Pony Friendship Is Magic. While real ponies can't talk, aren't colored in pastel colors, and don't have magically appearing pictures on their flanks indicating what career they're going to have, the show is quite accurate in other respects. In particular, the ponies move in realistic ways for equines, with their joints and legs moving in the proper order (something many other forms of media get wrong). There's also small touches, like ponies putting their ears back when angry or afraid, accurate references to equine anatomy in the song The Art of the Dress, and so on.
  • The G1 cartoons is probably the most accurate of the generations so far. The horses acted like horses and moved like them, especially in the specials. The cartoon series and The Movie were more anthro but to the same degree as G4.


  1. young wolves have blue eyes, but they change color as they get older
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