Confusing animals/Taxonomy Misconceptions

I’m writing up a list of misconceptions that people (particularly high schoolers) have about classifying animals. I would love to hear what animals you think people often confuse or misplace (e.g., “A dolphin is a fish!”). Give me your best confusing organisms! (Plants are good too).

Here is my list so far. Please correct me if you see any mistakes, and I would love to hear any additions!


Jellyfish: this is a cnidarian. Most students think it is a fish because it contains the word “fish.” Remind students that fish are way more complex. Fish have a head, brain, bilateral symmetry, digestive system, blood, endoskeleton, and vertebra. A jellyfish has none of these things.

Starfish: this is an echinoderm. Most students think it is a fish.

Scorpion: this is an arachnid. Some students think it is a reptile, because it lives in the desert with lizards and snakes.

Harvestmen: this is an arachnid. Students often call it a “Daddy long legs,” but it is not to be confused with spiders, which are a different category of arachnids.


Seahorse: this is a fish, and most students understand this. A few students think that it is in a different category than “fish” because of it’s unusual appearance.

Shark: this is a fish, and most students understand this. A few think it is a mammal because it is similar to a dolphin. This is a good way to bring up convergent evolution and analogous structures.

Salamander and newts: these are amphibians. A newt is a type of salamander. Many people think there are separate categories, but a newt is a subcategory of a salamander. People often think salamanders and newts are reptiles because of their lizard-like appearance. However, they are amphibians because they lay soft-shelled eggs in the water, go through metamorphosis, are cold-blooded, and do not have claws.

Frogs vs toads: these are amphibians. Many people think they are separate taxonomical categories, but actually a toad is a subcategory of frog. Toads tend to have drier skin and shorter legs than other types of frogs.

Turtles and tortoises: this is an aquatic reptile. Many students classify it as an amphibian because it is sometimes green and it lives in the water. They also forget that turtles have scales, and they think it has smooth skin like a frog.

Students may also not know the difference between a tortoise and a turtle. Many people think they are separate categories, but a tortoise is actually a subcategory of turtle. “Turtles” are an order, while “tortoises” are a family belonging to that order.

The order of turtles have a defining characteristic of a shell, which forms from its ribs. Other reptiles do not have a shell.

A tortoise is a type of turtle that only lives on land. Typically, tortoise shells are rounder than other species of turtles. Other turtles typically have flatter shells that streamline it for swimming**.**

Ichthyosaurs: this is an unusual category of extinct marine reptile. When students see it, they often think it is a fish (like a shark) or a mammal (like a dolphin). It is confusing since they gave live birth (like a mammal) and they have flippers (like a fish). It is not a fish because it did not have gills—instead, it came up to the surface to breathe, like reptiles or mammals. It is not a mammal because there was no fur, hair, or mammary glands present.

Crocodile and alligators: this is a reptile (specifically, an archosaur with a gizzard and 4-chambered heart, which are traits that make it a little more complex than turtles and lizards). Some students would accidentally classify it as an amphibian because they see it both in the water and on land. Sometimes they classify it as a mammal because of its large size.

Pterodactyl: this is a flying reptile (specifically, an archosaur). Many students classify this as a bird because it flies.
Students sometimes think that birds evolved from pterodactyls, but birds would’ve evolved from theropods (which includes T-Rex, velociraptor, oviraptor, etc.) Wings start a good discussion on convergent evolution and analogous structures.

T-Rex: this is a reptile (specifically, an archosaur). Because dinosaurs are extinct, students often don’t put them in the same schema or mental category as living creatures. They might say, “Dinosaurs are extinct and in their own category, they don’t belong to reptiles.”

Because some students have heard that birds evolved from dinosaurs, some students would put T-Rex into a “bird” category. However, a bird would be a subcategory of dinosaur, but a dinosaur would not be a subcategory of bird.

Manatee: This is a mammal. Many students have never heard of a manatee, sea cow, or dugong. It’s a good idea to include a picture of a manatee when discussing it. Because it is aquatic, some students are tempted to classify it as a type of large fish.

Dolphin: this is a mammal, which most students understand. A few would classify this as a fish, similar to sharks.


Waterthrushes are Warblers not Thrushes. They even made this mistake in the movie The Big Year (I did actually like this movie).

I had someone who saw a Shrike eat a sparrow, and because it was a bird eating a bird they thought it was a hawk. Actually it’s a songbird.

I frequently meet people who sort birds by size. Common ones are saying Indigo Buntings are finches, they’re closer to cardinals. It really gets fun to tell them that Rose-breasted, Black-headed, and Blue Grosbeaks are Cardinalidae. While Evening and Pine Grosbeaks are Fringillidae (Finches).

People often think bees fall into two categories: Honey Bees/Bumble Bees, and Sweat Bees that apparently don’t pollinate anything. Everything else is a hornet or wasp which are jerks. Actually there are quite a few different kinds of bees, the vast majority are pollinators and wasps are important predators and pollinators.


I guess it depends how in-depth you want to go! The more you look at different types of organisms, the more you start finding out weird things about what is and isn’t related. And I guess it also depends how in-depth you want to go. Here are just a few examples that I can think of:

The slow worm, sometimes called a deaf adder or a blind worm, is neither a worm nor a snake, but a type of legless lizard. But snakes themselves are actually a type of legless lizard as well! The extinct mosasaurs were also a specialised type of lizard, but New Zealand’s tuatara is not a lizard at all despite looking very much like one.

The killer whale is a species of dolphin, but all dolphins are themselves a type of whale, so that one’s not really a big deal.

The sawshark is a type of shark, but the very similar sawfish is instead a ray despite looking very much like a shark.

Termites look very much like ants and are sometimes called ‘white ants’, but they are not closely related, and in fact termites are a type of cockroach, whereas ants (and bees as well) are a type of wasp! Similarly, aphids are sometimes called ‘greenflies’, but they are not a type of fly at all - and neither are dragonflies, butterflies, sawflies, or mayflies. And oddly enough, insects themselves are actually a type of crustacean! Within crustaceans there are many crazy things that don’t make sense - e.g. hermit crabs are not actually a type of true crab, and mantis shrimp are definitely not shrimp!

Caecilians look rather like large earthworms, or perhaps an odd snake, but they are actually amphibians. Blind snakes are also often mistaken for worms, but they are indeed snakes as the name suggests.

Some animals, like corals or sponges, may be mistaken for plants or for each other, but of course they are animals and they are not very closely-related to each other either.

Eels and sea snakes may easily be confused for each other, and there are many different types of fish that have taken on an eel-like body but are not closely related.

As well as harvestmen like you mentioned, there are also many different arachnid groups that might be mistaken for spiders and scorpions - vinegaroons, amblypygids, solifuges, schizomids, and even non-arachnids like sea spiders, bat flies, some crabs, and mimics like the spiny leaf insect.

Jellyfish, comb jellies, and salps look very similar to each other, but none of them are closely-related at all.

Eagles, hawks, and kites are all closely-related, but falcons are completely different, as are owls and their unrelated lookalikes, frogmouths.

Worms are probably the worst of them all! Earthworms, tapeworms, ribbon worms, peanut worms, nematode worms, acorn worms, ship worms, penis worms (yes really!), acoel worms, tongue worms, thorny-headed worms, horsehair worms, horseshoe worms, slow worms, jaw worms, arrow worms, and velvet worms are all in completely different phyla, so they are about as distantly-related as it is possible to get within the animal kingdom!


Many people still think that shrews are closely related to mice. They are more related to elephant instead.

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That bug - small and way too many legs! - may be a spider or … not an insect.
A bug has biting sucking mouthparts - if you are a bug person?

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A lot of students and regular people confuse true bugs (Heteroptera) with beetles (Coleoptera).


I’ve seen that confusion too, here on iNat. Interestingly it might be a language issue: I’ve never come across a confusion of ‘Käfer’ and ‘Wanzen’ in German.

Ajott, we are even worse off in Denmark: In Danish, the common name for true bugs is “tæge”, which comes from an archaic word for “attached by suction” in old Danish. BUT outside of naturalist circles, blood sucking ticks (Ixodidae) are also called “tæge” (their REAL common name is “flåt”).

So, we have an insect order and an arachnid order sharing the same common name, which is SO annoying!

I have to say, I also blame our shared Aristotle-bagage for the whole “invertebrate” lumping group. It breeds so many misconceptions, and lumping everything outside our own phylum into one muddled lump does no good what so ever. Worst, it maintains the misconception of directional evolution with our species at the pinnacle - which is also Aristotle, of course. What a nuisance that man was! :)


I don’t blame him so much. More the many, many generations after him who forbade themselves to think independently from or even critical about his writings.


A couple of minor clarifications (which might or might not matter depending on the situation):

Sharks are Chondricthyes, or cartilaginous fish, as opposed to the bony fish. Bony fish are actually more closely related to us than to the sharks, surprisingly enough.

The distinction between turtle and tortoise actually varies between the US and the UK. If I remember correctly, in the UK turtle refers specifically to sea turtles, and tortoise to all of the Testudines.

Then you are lucky. I am basing this judgement actually mainly on my experiences from Germany (university and lurking around in nature photographer groups and seeing this mistake being made over and over again) :-)

It´s not so much about the name, it´s honest confusion because they look so much alike, if you do not know what to look for.

The whole “same name, different organism” is another can of worms I rather not dare to open now… we of course also have lost of those in german language and the ylead to lots and lots of confusions :-)

Oh, I didn’t mean to say Germans can tell them apart. But I think they at least understand that ‘Wanzen’ and ‘Käfer’ are denominating different groups of organisms. I had the impression that in English some people use ‘bugs’ and ‘beetles’ as synonyms. But maybe that’s just me misinterpreting.

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A few common ones I’ve heard:

-Penguins are mammals
-Armadillos are reptiles
-Coral are plants
-Apes vs monkeys (they get mixed up all the time)


And all of them are buzzards.)

Here those are also two different words (жук/клоп), but people seem to use them just as they wish when refering to small insects or even arachnids, similar to how bug is used in English, not surprising when e.g. Galerucinae have official name of boogers.

Here there’s no distinction, apes are just a group of monkeys.


I think a lot of people assume that all the reptilian-looking things around at the time of the dinosaurs were dinosaurs.

Dimetrodon, ichthyosaurs, plesiosaurs, pterodactyls, etc. Many of them have names that end in -saur, are featured in dinosaur movies and cartoons, even look ‘dinosaurish’ (whatever that means). But none of these are dinosaurs.


In my experience, people generally know very little about non-human life. Animals are mammals or birds - beyond that, Life becomes generalised. Any invertebrate is a bug or a creepy thing, something to step on or be afraid of. All snakes are just snakes, that sort of thing. Common names really confuse things - Ladybugs, all the non Diptera with ‘fly’ in their names. Dragonflies, Mayflies.
I’m still learning things all the time. It wasn’t until last year that I found out that falcons are closer to parrots than the other raptors. But at least I knew enough taxonomy to ask the question. If something is not edible, a pest, or pretty, it’s just ignored. Mind you, people also don’t know much about other people, especially those from unfamiliar cultures.
And on that cheery note, I’ll go back to my moths.


No, apes are primates but not monkeys, they are a separate group.

Apes are in Catarrhini, which are monkeys, all monkeys are primates of course.

This depends on whether you’re using a cladistic approach to common names or a traditional one. Monkeys comprise two groups, one in Africa & Asia, the other in the Americas. Apes are indeed in their own family, but they’re more closely related to the Old World Monkey group than either are to the New World Monkeys. So, if monkey is a taxonomic term, then it has to include the apes in the Old World monkey group. Similarly, if ape is a taxonomic term, then we have to include humans in it.