Taxonomic Term Confusion

Taxonomy, the classification of living things, is really complicated. For example, anyone who's worked in a record store and had to fit every band into one neat little category or other has an idea as to why: Many organisms defy traditional or obvious categories in the absence of genetic studies. This is why there is such a wide variety of terms for organizing living things (and theoreticians regularly come up with new ones).

Writers of fiction tend to tidy things up a bit. They regularly come up with creative ways of employing normal classification terms in ways that are incredibly inappropriate. Primarily, what seems to be at fault is a failure to recognize that the terms for taxonomic categories have specific meanings, and are not just interchangeable synonyms for "a big group of similar things". Sometimes they do know better; it's just that they couldn't resist the Beast Fable pun of having an Animal Kingdom. You know, where the lion is the King.

For the record, any group of related organisms, regardless of the degree of relatedness, is called a taxon. The major recognized taxonomic ranks are:
 * Domain
 * Kingdom
 * Phylum/Division
 * Class
 * Order
 * Family
 * Genus
 * Species

(If you're having trouble remembering, remember this simple mnemonic: "Danny Kaye, Please Come Over For Good Strawberries" or, if you prefer, "Dear King Phillip Came Over For Good Soup". A commonly-used one is "Dumb kids playing catch on freeways get squashed". Before "Domain" was added to the top of the list, mnemonics were "Kings Play Cards Only For Gold and Silver" and "Kings Play Chess on Fine Glass Surfaces.")

Compound variations on these terms such as "subspecies" and "superfamily" are in common use. Some taxonomists also make use of the term "tribe" for a rank intermediate between subfamily and genus. This is not just limited to fiction; in a strictly factual sense birds are technically reptiles, and the whole animal, plant, fungus distinction is being rewritten of late so more often than not, it's hard to know the correct terminology because it always is changing. It doesn't help matters that the current system was invented before evolution was understood, and that the ranks are pretty arbitrary. One "genus" might be older and more diverse than another "family." Some scientists even want to abolish taxonomic ranks, though that's not likely to happen soon.

The scientific Latin name for a species consists of the genus name (capitalized), followed by the species name (in all lower case), both italicised. Tyrannosaurus rex is genus Tyrannosaurus, species rex; Homo sapiens is genus Homo, species sapiens. If the species is well known, or has already been mentioned earlier in the same work, the genus name will frequently be abbreviated to a single letter, e.g. T. rex or H. sapiens. If more hairsplitting is needed, the subspecies or variety name can be appended as a third word, e.g. Homo sapiens sapiens.

Frankly, it's not surprising that writers are sometimes ignorant or confused. Though this can also turn into a case of Fan Wank as many of these words also have different less precise meanings in regular English as in family and class are both used to refer to groups of similar things, a class of ships, the t-series family of trucks so a lot of these errors are just people using the words with their regular meanings. But there's really no excuse for the examples under "General", especially by scientists.

Of course, things are also more complicated than even this. Cladistics, Dendrograms, Phylogenetics... We'll just leave it at this lest Your Head Asplode.

General

 * Most common is using the word "race" where "species" would be more appropriate. Science-fiction series with multiple sapient alien peoples are a big offender here.
 * Fantasy settings do the same thing, but whether it's as bad in such a case is more debatable since there are often No Biochemical Barriers either. (If humans and elves can interbreed, producing fertile offspring, who's to say that they're not different races within a single species?)
 * It should be pointed out that the definition of species is not absolute. In rare cases seemingly very different creatures can interbreed and produce fertile offspring. A good example is the case of a false killer whale and bottle-nosed dolphin (both dolphins but very different in shape and structure) which produced a fertile calf in captivity. Animals in the same genus such as tigers and lions are even more likely to interbreed.
 * The consensus usually is that No Biochemical Barriers means they're the same species. It's also sort of determined on how often this occurs. One or two exceptions doesn't break the rule.
 * In a fantasy setting, it's sometimes stated explicitly that a given "race" was created from scratch by divine agents. In that case, it's not technically related to any other species at all in real-world terms. But since it's also likely to be very similar to them, the whole set-up just can't be understood in the same terms.
 * Usage of the word "race" to mean "species" in Speculative Fiction is probably an archaism, which stayed as a sort of genre convention.
 * Indeed, "race" was used to mean "species" in common and scientific speech until relatively recently. It was extremely common in the nineteenth century. It can be an easy way to create an old-timey mood in a fantasy story.
 * Referring to a group of related species (a genus) as a single species.
 * There are two known species of Velociraptor, three of Stegosaurus, and two of Triceratops.
 * There is only one species of Orca now - there are several well-defined types which may need to be promoted to species though.
 * In many cases the number of species is debated by different scientists. It is also often debated about which species go into which genus, since genus itself is even less concretely defined than 'species' (i.e. to some extent species are a biological reality while all higher classifications exist only as a rather subjective human system of classification).
 * Referring to a species by the proper name of its family/order/etc. instead of the anglicized form. A human is not a Hominidae. A human is a hominid, a member of the family Hominidae. Doing this wrong is like referring to an animal as "an Animalia" or a plant as "a Plantae".
 * Use of family when order ("the owl family") or genus ("the horse family") would be more accurate.
 * Describing a newly discovered and radically unusual life form as "a completely new order of life": Kingdom or phylum or even domain would probably be more accurate. New orders are created all the time, sometimes on the whims of the researchers. (It's not just Tropers who have to deal with Lumper vs. Splitter arguments!)
 * Using the word "phylum" interchangeably with "taxon" because it sounds all science-y and no one knows what "taxon" means. (And no, "giant wormlike alien with an insatiable hunger" is spelled with a Double X.) The reason for this odd usage may be historical: phylum was a synonym of "taxon" until Ernst Haeckel (who abolished polyphyletic groups from scientific classification) decided that a new rank was needed between kingdom and class.
 * Pretty much every instance where lifeforms evolved independent of Earth are referred to as mammals, birds, etc. Bonus points if the author just can't seem to understand that it's not a rule of the universe that lactation and fur go together (or feathers and eggs, etc.).
 * It's even proven here on earth that nature sometimes bends its own rules with the echidna and platypus, both species of mammal that fall into the monotreme order, meaning that they lay eggs.
 * Calling apes "monkeys". Ignoring that the order of primates includes humans.
 * This guy disagrees.
 * Don't do this one near The Librarian: It's his Berserk Button.
 * Heck, far too many apes are too quick to forget that humans are one of the great apes—not merely related. Blame the early 20th century biologists who made damn sure that hominids get far more special treatment than the genetic variation warrants.
 * It depends on your definition of 'monkey'. Monkeys as a group are useless in taxonomy if humans (and other apes) are excluded. "Tail-less simians" are do not share a single common ancestor that apes don't.
 * In French, the word singe, translated in "monkey" en anglais, mean "more or less all primates that are not humans"... Singe (and probably "monkey") means something more cultural than biological.
 * Lampshaded in the Planet of the Apes remake. When one of the humans called the apes "talking monkeys", one of them pinned him down and reminded him that monkeys were lower on the evolutionary ladder.
 * Although "lower on the evolutionary ladder" is itself a biology fail.
 * On an episode of Sale of the Century someone got points for saying that a Baboon was an ape. They're actually Old World monkeys.
 * The use of "ape" as "simian", as in Dutch or German, may be rare in English, but it is not extinct.
 * All in all, one should remember that, in biology, something never stops being what it once was. Apes descend from monkeys (but not from living monkeys), and, therefore, ARE monkeys themselves. Just like humans are apes, monkeys are primates, and primates are mammals. The dichotomy between ape and monkey to the extreme seen here is mostly a case in English speaking circles.
 * Calling dolphins "fish."
 * Any reference to "the fish class" as if there were only one, probably refers to ray-finned fish, you'd hope. There are actually three: cartilaginous fish (sharks and rays), lobe-finned fish (very obscure, mostly coelacanths and lungfish) and ray-finned fish (everything else).
 * It's not all that long since actual taxonomists put all fish in a single class, and school biology textbooks probably still do. Being a bit behind the cutting edge of classification is a very minor sin - there are piles and mounds and mountains of more substantial errors to complain about in Hollywood Biology.
 * There is a dolphin fish. There's also a dolphin mammal. For some reason, the dolphin mammal gets accused of being a fish frequently but the dolphin fish is rarely accused of being a mammal. The latter is often referred to by other names to avoid unfortunate misunderstandings; fishing magazines (and Animal Crossing) often refer to the Dolphin (fish) by its Spanish name, Dorado, while most restaurants call it mahi-mahi.
 * An example can be seen in this Comic book PSA
 * Under "strict cladism", dolphins are fish — along with birds and humans. Strict cladism holds that no species ever "loses" any of the categories it is descended from, so, eg, all birds are dinosaurs, because they arose from a group of theropods. Since all mammals are descended from synapsids, synapsids from amphibians, and amphibians from fish, well, there ya go.
 * A "lizard" and "reptile" are not interchangeable words, the latter includes snakes, crocodilians, turtles, and possibly birds. "Lizard," on the other hand, contains creatures as diverse as geckos, iguanas, chameleons, and monitor lizards (a category that includes the Komodo Dragon).
 * You're going to get very odd looks calling birds "reptiles" around any but the most hardcore phylogeneticist.
 * Tyrannosaurus Rex is always spelled T-Rex in most media, despite the proper way to abbreviate it is T. rex.
 * Heck, messing up the format of genus and species is so common, it deserves a trope of its own. For the record, the genus (Tyrannosaurus) is capitalized, the specific name (rex) is not, and you always underline/italicize it.
 * For the record, dinosaurs are NOT lizards. They are both reptiles, if one grants that reptile is actually a valid classification, but they are not the same thing. To put things in perspective, it would be like calling a human a "mouse" since both are mammals. Also, recent overwhelming long-overlooked evidence indicates that dinosaurs are more closely related to birds than lizards; in fact, as any paleontologist will do their best to get into your head, BIRDS ARE DINOSAURS., but those that disagree are not to be believed.}} Therefore, it would be more accurate to call a Tyrannosaurus an "overgrown chicken" rather than a "big lizard'.
 * This, and the gorilla=monkey thing, is often more of a case of Did Not Do the Research than of trying and failing to get the genus/family/whatever correct. It's easier to call something a monkey than it is to call it the Super Magnificent Hominid Ultra Gorilla Of Doom.
 * Of course, a gorilla is a monkey, as detailed in the link above.
 * On the other hand, -saurus is the latinized form of the Greek word for lizard, and thus calling it lizard is justified on linguistic, rather than taxonomic, grounds, and that would even go for Basilosaurus.
 * Speaking of what is and what isn't a reptile, Dimetrodon and other so-called mammal-like reptiles (synapsids) are NOT reptiles, despite looking like lizards. That, until you check the bones, or the skin, seeing they kept the fish-like scales of their ancestors (which are pretty different for those of reptiles), and their glandular skin. Y'know, the kind of skin that oozes liquids. As when you sweat.
 * Just as a reminder: While many turtles are amphibious, none of them are amphibians. Conversely, despite having a similar body shape to lizards, newts and other salamanders are not lizards or reptiles at all, but amphibians.
 * Using "evergreen" and "conifer" as synonyms. Some conifers are deciduous trees; for instance, No. 1: the larch. The larch. The LARCH. In warmer climates, many broad-leafed trees are evergreen.
 * Using "rodent" to refer to any small mammal. Forgivable when applied to rabbits, which are in order Lagomorpha, closely related to Rodentia (together they form the clade Glires ), and have gnawing teeth of their own...not as forgivable when applied to, say, weasels (which are Carnivorans) or bats (Chiroptera). Despite that in many European languages the word for bat is a compound of the word for mouse, bats aren't rodents, as Batman says in Batman Forever. (Of course, bats aren't bugs either.)
 * In the same vein, trying to go technical and call every small non-rodent mammal an "insectivore" is also equally wrong. Genetic tests have proven said order was made up of vastly different animals: while hedgehogs, moles and true shrews are a real group, tenrecs, for example, are relatives of ELEPHANTS.
 * So...the elephants were scared of tenrecs because they might get that small?
 * The word "bug" is commonly applied to any arthropod and in some cases to any invertebrate at all, but it's actually a specific term for a single group of insects, just like the word "beetle" or "moth". Bugs are only insects of the order Hemiptera.
 * Having said that, good luck getting people to start calling them "arthropods." It just doesn't roll off the tongue the way "bug" does.
 * A very common "mistake" is calling everything in media that one can ride a horse. This gets especially glaring when people use it on creatures that look nothing like horses, for example Yoshi is often called one.
 * Even further anything that flies is often called a bird and any bird is referred to as a chicken.

Comic Books

 * X-Men has many examples of You Fail Biology Forever, but two things are worth noting: The mutants are referred to as a new species, but they can breed with non-mutants; so no, the term mutant, or at least subspecies, is far more accurate. (Though the deciding factor would be if the offspring of mutants and non-mutants breed; else lions and tigers could be the same species.)
 * Subspecies have to have some factor that prevents them from breeding most of the time, like geographic separation or something, which doesn't happen in X-Men. The fact that mutants differ only from baseline humans by the "x-gene" means that mutants just have a different phenotype and are thus more closely related to baseline humans then gingers are related to blonds.
 * With a few exceptions, none of them can have the same mutation, despite what they all claim. Then again, at least one of them has a mutation that allows Time Travel, to say nothing of the couple of dozen Reality Warpers, so...
 * Third, it's usually Magneto who claims that mutants are a new species, and he is, for all intents and purposes, a mutant-Nazi, not particularly intent on letting reality get in the way of his delusions.
 * Nazi Science sneers at your version of taxonomy!
 * The classic definition of species that textbooks push so hard, that is, a group of individuals who can breed together to create viable offspring, is bull. Tigers and lions can breed to create fertile hybrids. It can happen in the wild as well, there have been accounts of hybrid baboons born from Anubis and Hamadryas parents. Ring species outright make the definition useless. Red wolves are most likely a cross-breed between grey wolves and coyotes, traditionally considered separate species. Defining species entirely on reproductive capability is, in a word, incorrect.
 * But whatever a species is, it must involve a common ancestor for all members of that species. Marvel mutants commonly arise from purely normal human parents, i.e. there's no common ancestor involved. Therefore Magneto is full of it. Biologists in the Marvel universe would probably have a ton of arguments on the subject of classification.
 * Especially since there is at least one case of two mutants producing non-mutant offspring: Mystique and Sabertooth's son, Gordon Creed, aka Victor Creed, Jr. I also heard...somewhere that mutants tend to be closer genetically to a random human than they are to random mutants due to the wildly different forms of mutations around.
 * In fact, there are several "species" of lizards - several whiptails, for instance, and several types of frog - that are actually hybrids, and need their parent species to breed, or breed asexually on their own, and which have existed for millions of years. Our current definition of species has so many problems with it that it's really only taught at the high school level for ease of convenience, and one of the first things university will do to you is tell you it's far too simplistic.
 * Of course, every human, nay, every individual of any species born is almost certainly a mutant, several times over, by the actual definition of the term. A typical human may have dozens of alleles (that is, genetic variations) not present in either of its parents. These are all mutations.
 * Subverted in a Star Wars comic in which Jaxxon, a rabbit character, says "I ain't no rodent!"
 * Of course he's a alien Petting Zoo Petting person so he's hardly a rabbit either.

Film

 * In The Horror of Party Beach, a doctor explains that the monster is actually a dead human whose organs were invaded by aquatic plants before they had the chance to decompose, and calls the result "a giant protozoa." Protozoa are single-celled lifeforms, being neither plants nor animals. "Protozoan" is the word for describing one in the singular.
 * The Faculty contains this line: "We discovered a new phylum in biology class today; maybe even a new species." This makes no sense, because something in a new phylum would have to be in a new species. Probably the actor accidentally switched "species" and "phylum" around from the scripted line, and nobody caught the mistake.
 * The ikran in Avatar apparently have the scientific name Pterodactylus giganteus. No. This is wrong. Being members of the genus Pterodactylus would mean that they're small pterosaurs from Earth's Late Jurassic period. For those not in the know, it's actually a four-winged dragon-like beast from a moon in the Alpha Centauri system. So yeah...
 * The Na'vi themselves are classified as Homo pandora, which would mean that they are closely related to humans. As we know they evolved from some sort of alien lemur creature, and not hominids transported from Earth, this is wrong.
 * Maybe they switched to a classification system based solely on homology to help classify alien life?
 * Or they've built an entirely separate phylogenetic tree for Pandoran life, and designated the Na'vi genus as "Homo" solely as an analogy rather than as a statement of literal relatedness, much like how many Real Life dinosaurs' names contain references to lizards or birds that aren't close kin to them.
 * No biologist would ever do something like that. While it's quite common to give a new species a name that contains a reference to another species or genus, to actually put a completely alien species into an existing taxonomic group which they know it's not related to is a mistake on the same level as someone trying to stick the marsupial koala into the Ursus genus.
 * It is actually perfectly normal to have species in two different kingdoms have the same genus. Example: Helopus, which is both the genus name for a bird and a kind of grass. Biologists probably placed Pandoran wildlife in a new kingdom, heck, maybe even a new domain, because it didn't live on Earth! It'd be perfectly fine for Pterodactylus to be the ikran and the pterosaur, because if Pterodactylus was also a kind of tree, it'd be perfectly fine!
 * In Jurassic Park, Alan Grant says that humans and dinosaurs are "two species separated by 65 million years." Granted, that line probably sounded great in the trailers, but you'd think a paleontologist would know better than to call dinosaurs a species.
 * "Let's name the species of the open seaaaaaaaaaaaaaa!!!" The "species" mentioned in Mr. Ray's song are actually phyla.
 * In Disney's The Sword in the Stone, for Merlin and Mad Madame Mim's Wizard Duel, the two spellcasters are only allowed to turn into animals, and not vegetables, minerals, or "nonexistant creatures like pink dragons and such." However, when the duel is over, Mim breaks one of her own rules by turning into a dragon, and Merlin defeats her by turning into a germ, which is not even an animal at all!

Literature

 * The Childcraft book About Animals identifies arthropods as a "class" of animals, when it really is a phylum. It could be argued that phylum is too advanced a word for a book aimed at 6-year-olds, but that could also be argued of arthropod, and that didn't stop the publishers. (Probably they figured that anything was better than risking spiders getting classed as "insects".)
 * Even more Egregious as there are more arthropods in existence than every other phylum of animals combined.
 * The Book of College Pranks: In relating a story about how a cow was elected Homecoming Queen because all the human entrants were disqualified, it says that the cow "was in the wrong phylum, but at least had not cheated." In fact, cows and humans are in the same phylum (Chordata), and even the same class (Mammalia), and, inside mammals, they are remarkably quite close, even in distinct orders.
 * In Cachalot, a marine biologist refers to a newly-discovered undersea race as "the first intelligent invertebrates we've ever encountered". Granted, this wouldn't be an issue in some scifi series ... but Cachalot is one of the Humanx Commonwealth novels, where humans and thranx have been virtually joined at the hip for centuries. Did Alan Dean Foster forget that his insect-based thranx also lack an internal skeleton?
 * Perhaps they meant the first such species encountered in an aquatic environment?
 * He also repeatedly refers to shrews as "rodents" in his Spellsinger series.
 * In The World Of Kong: A Natural History Of Skull Island, Venatosaurus—the raptor-style therapod dinosaur from the 2005 King Kong—is described as a dromaeosaurid. But the species for which that taxonomic group is named, Dromaeosaurus, was extremely obscure, only known from one damaged skull and a few foot bones, and assigned to a different family entirely, at the time Carl Denham's group first discovered Skull Island. It wasn't until the 1960s that Ostrom's work on Deinonychus elevated Dromaeosaurus to the Trope Namer for an entire Real Life family of dinosaurs. If a creature as spectacular as Venatosaurus had been discovered before Deinonychus, then Ostrom would've surely compared his Deinonychus fossil to that species rather than to Dromaeosaurus, and the raptor taxon would've been named venatosaurids, not dromaeosaurids.
 * Bored of the Rings has an appearance by "six different phyla of giant insects". Insects, whatever their size, are a single CLASS of phylum Arthropoda.
 * Melville spends an entire chapter of Moby Dick committing an extended crime against taxonomy. He starts by classifying whales as "spouting fish" and proceeds from there.
 * Of course, Moby Dick was written in first person perspective from the POV of a not especially well educated man in the early 19th century, when it's likely that someone actually would think that a whale was a fish.

Live Action TV

 * The female scientist near the beginning of the series Surface described the creature she'd seen as "An entirely new phylum of mammal!" This is especially mind-boggling when we later learn that the creatures are created from the DNA of liopleurodons(a prehistoric sea reptile)... which she describes as "A type of prehistoric eel"... You know, just stop trying.
 * Anyone else want to punch the screen when Doctor Who gave the (reptilian) Silurians the name "Homo reptilia"?
 * Occasionally a host of a Food Network show will try to emulate Alton Brown's use of scientific terminology, and wind up sounding like a Know-Nothing Know-It-All. The host of Food Feuds, for one, has openly referred to clams as crustaceans, apparently on the assumption that all seafood without fins is in the same taxon.
 * The main character in Prey claims in the pilot to have discovered a new species after analyzing a DNA sample with a 1.2% difference from a regular human. They later proceed to name the new "species" Homo dominants, apparently unaware that you're supposed to use Latin for this.
 * Actually, a 1.2% difference might actually enough difference to classify as a new species- if that group consisted of a reproductively isolated population. The "new species" from Prey, of course, freely intermingled with the rest of humanity.
 * An episode of Fringe features what looks like a cucumber-sized slug that crawls out of its victim's mouth, which the cast later identifies as an enlarged single-cell cold virus. I repeat, a single-cell virus.
 * The narrator on Monsterquest seems to have confused "species" with individuals, inverting the usual pattern where higher-than-species clades are mixed up. The voiceover claims that "millions of species" of fishes are found off the coast of Florida, which is a couple of orders of magnitude more than the actual number of fish species on the planet (~32 thousand).

Tabletop Games

 * In an aversion, Shadowrun seems to get the race/species thing right. The book mentions that Metahumanity (Humans, Dwarves, Elves, Orks, and Trolls) are all different races within the same species. They can even interbreed (at least, they can this early on in the Sixth World), though they don't create Half Human Hybrids when they do. If, for example, an elf and a human mate, the child will most likely be either an elf or a human. Or maybe a dwarf. Things are weird in the Sixth World.

Video Games

 * Subverted in Mass Effect, in which the names of the various alien species are very carefully non-capitalised, thus avoiding the common assumption that an alien planet is just another country but a bit further away.
 * Also recently subverted in Star Craft 2. Whereas the previous game (and early Expanded Universe materials) capitalized species name as is often done in science fiction (erroneously), Star Craft 2 promotional materials and the new books all spell "protoss" and "zerg" with non-capitals. The fandom hasn't quite caught on yet.
 * Hidden object casual games regularly invoke this trope, as when clicking on a "seahorse" isn't registered as finding a "fish".
 * Averted in the Warcraft franchise, where across all media species names are almost always left uncapitalized. However, many, many fans do so anyway.

Western Animation

 * Elmer Fudd calling Bugs Bunny a rodent.
 * An episode of The Angry Beavers does this, as well. Rabbits are lagomorphs, not rodents, though Rodentia and Lagomorpha are sister orders in the clade Glires. However, in the Elmer Fudd case at least, the mistake is perhaps forgivable. Indeed, taxon Lagomorpha was placed within Rodentia until at least early 1900's, making then-Rodentia equivalent to now-Glires, and Fudd was already depicted as a middle-aged man in 1940.
 * Family Guy's Meg Griffin calling a raccoon a rodent. They're actually members of the order Carnivora, close relatives of BEARS. Rodents and carnivores are both boreoeutherian placental mammals, but that's almost literally about as far as their taxonomic relationship extends. It's like saying we humans (which are primates) are related to horses (which are perissodactyls).
 * Life After People: The Series did the same thing.
 * On Futurama, Fry came into possession of the last remaining can of anchovies on Earth, the species having gone extinct centuries ago. There is no such species as "anchovy", this being a catch-all term for some 140 species of small fishes.
 * Jackie Chan Adventures had a weird one in which jackie and a crime boss refer to an octopus as a fish and respectively are corrected by Captain Black and a random mook by saying it is a multipod. What makes this a headscratcher is that the correction is more incorrect then the original statement because there is no taxon called multipod nor has one ever existed.