Remember all those internet  memes about how every animal, including humans, will  eventually turn into a crab?

They’re only mostly wrong. Evolution has indeed mutated multiple  crustacean species into a crab-like form.

It’s a process called carcinization, and scientists know it’s  happened a whopping…five times. Yeah, only five. Which is why I’m here today: to share that while it might be fun to  picture your descendants scuttling around, going pinchy with their claws, the  memes should really look like this.

Because even more than crabs, evolution  keeps turning things into ant-eaters. [♪ INTRO] We all know what a crab looks like. Ten legs; a wide, flat, rock-hard shell; an abdomen completely curled  underneath said shell; no visible tail. And of course, those snippy-snippy pincers.

But if you’ve ever drowned a  bit of king crab in butter… you weren’t actually eating a crab. And if you’ve ever had a pet hermit crab…sorry. Also not a crab.

Yes, I realize the word is in their name. And sure, they do have a  suspiciously similar body plan. But that’s just two examples  of carcinization in action.

See, true crabs fall under the  taxonomic suborder Brachyura, and they include species like fiddler  crabs, spider crabs, and blue crabs. Meanwhile, both king and hermit crabs are  classified under the suborder Anomura, a.k.a. the “false crabs”. Members of Anomura may look  like true crabs at a glance, but there are a few obvious  differences if you know your stuff.

For example, true crabs use  four pairs of legs to walk, while false crabs only use three. You can also distinguish the  placement of their antennae, whether their shell is fully fused or segmented, and whether their tucked-up tails  have a little fan on the end. The last common ancestor of both these groups probably lived around 250 million years ago.

It also may have looked more  like a lobster than a crab. Then eventually, we hit what scientists  call the “Cretaceous Crab Revolution.” If you’re thinking “hey that  sounds like a great band name”, you’re not alone. There’s already a band called that.

Between roughly 145 and 66 million  years ago, crab diversity exploded. And from that revolution onward,  basically any creature that evolved crab-like features, but didn’t  evolve from a Brachyura ancestor, counts as a false crab. All this carcinization is yet another  example of convergent evolution, where unrelated species evolve  similar characteristics.

Scientists don’t know exactly  why evolving to look like a crab is such an evolutionary go-to, but  there are certainly plenty of perks. For example, the general form  slots pretty easily into a bunch of different environmental niches, and  it’s quite a protective body shape. After all, if you don’t have  a big ol’ tail sticking out, that’s one less thing for a  predator to monch down on.

And all those appendages could provide you an evolutionary Swiss army knife of sorts. You could dig; you could swim; you  could scuttle; you could…climb trees. Yes, some crabs can climb trees.

I am only slightly terrified. Crabs and crab-like species have made  it work in a wide variety of habitats, from underwater caves to mountain streams. As I mentioned earlier, scientists  estimate that carcinization happened five separate times,  over the last 250 million years.

To which the ant-eaters throw  their heads back and laugh. Because in less than half that  time, they’ve managed to evolve twelve separate times…despite scientists  not having come up with a name for it. Now, I should clarify that when I say “anteater”, I’m not just talking about the long-haired, long nosed inspiration for the Pokémon Heatmor.

I’m talking about the  taxonomic suborder Vermilingua. I’m also talking about Arthur the  Aardvark, Knuckles the Echidna, and…uh…whatever fictional character  someone’s turned a pangolin into. So if on one hand you’ve got  true crabs and false crabs, I guess on the other you’ve got true anteaters and false anteaters which also eat ants.

Also they all eat termites, which isn’t  incorporated into the name at all. Because the technical term for  this behaviour is myrmecophagy, which is Greek for ant-eating. Animals that exhibit myrmecophagy  are called myrmecophages.

Myrmecophagy likely evolved so  animals could take advantage of a super abundant nutrient source. Ants and termites are chock  full of proteins and lipids. And they’ve also got some sugars, too.

Together, these two types of insect make up about 45% of the Earth’s total  terrestrial insect biomass. If you could find a massive enough scale… and passionate enough graduate  students to do your specimen wrangling… then put every living termite  on one side of that scale, and every living wild mammal on the other,  the scale wouldn’t be balanced at all. Because the termites would  weigh like 10 times more!

It’s, just, an unbelievable  amount of ants and termites. They also live in huge,  densely populated colonies. So even if each ant or termite is tiny,  a whole serving size is easy to slurp up.

Anteaters eat up to 35,000  ants and termites a day. Numbats, an adorable Australian marsupial,  can eat 15-20,000 termites a day. And aardwolves…which sound like  one of those animal mashups from

Avatar: The Last Airbender, but are  indeed a real animal related to hyenas… can eat up to 200,000 termites a day. Still, ants and termites are tiny. So some myrmecophages have evolved to  maintain a cooler body temperature, and slower metabolism, to handle  such a low-energy food source. Personally, I’ve never tried ants,  but I have heard they’re fine.

They taste a little bit  like salt and vinegar chips. And now that we’re all thinking about  snacks, it’s time for an ad break. Thanks for watching SciShow and  learning new science stuff with us!

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Thanks to convergent evolution, all these myrmecophage mammals have  developed similar characteristics. Perhaps most iconic is the sticky, worm-like tongue that pops in  and out of a tube-shaped mouth. That mouth usually doesn’t have teeth, though.

And most ant-eating species don’t chew their food. Even animals that eat other creepy  crawlies, in addition to ants and termites, tend to swallow their tiny, buggy meals whole. Chewing up every single one of your  thousands of ants would likely take up a lot of time and energy, so  that’s one reason to skip the step.

Plus, crushing the bugs completely could release a bunch of toxins inside their little bodies. Toxins they’d normally use to prevent  themselves from getting eaten, by making the animal go “ew gross  I’m never eating that thing, again”. But a quick swallow isn’t  the only way myrmecophages handle those nasty chemicals.

For example, according to a paper from 2022, pangolins have extra protein molecules  that hang out in their livers and break down the formic acid made by ants. They also make use of any formic acid  left in their stomachs for digestion, instead of making their own stomach acid. Which is pretty ingenious if I do say so myself.

Speaking of breaking down, myrmecophage  stomachs have adaptations to digest both the chitin in the insect exoskeletons, and the sugars in the insects’ version of blood. That same 2022 paper also found  that myrmecophage DNA is filled with the instructions for different  chitin-digesting enzymes, at least compared to other mammals. Also, their bodies might use those instructions to create enzymes more frequently  than other mammals do.

And that’s not all. Ant-eating mammals also  appear to have significantly more chitin-digesting bacteria in their stomachs. Wait, a crab’s shell is made of chitin.

Could an anteater digest a crab? Or any of those fake crabs being served  at your local seafood restaurant? Have I managed to truly unite these  two stories of convergent evolution?

Honestly, probably not. Look at their tiny little mouths! Most myrmecophages have a fused jaw,  not built for unhinging or chewing.

It might be able to digest the shell  if it were crushed up into tiny pieces, but even animals that naturally eat crabs  in the wild tend to leave the shells behind. No, sadly it looks like the only  victory anteaters have over crabs is in the battle of carcinization  vs. anteaterization. Or whatever scientists eventually come up with.

Maybe they’ll finally find a  way to give termites their due. Whatever you call it, there were twelve separate events throughout mammalian history. That’s more than twice as many  times as carcinization occurred, in like one-quarter the time.

As for why this anteaterization  happened so many times, a paper published in 2025  provides one possible reason. The researchers hypothesized  it had something to do with the evolution of their food source. And lacking any sort of time travel  technology…and in an even more ideal world, some kind of Speak With  Animals potion to interview some ancient aardvarks or whatever… they had to turn to more  typical experimental methods.

They collected dietary data  from nearly 4100 mammal species, and mapped those diets onto an evolutionary tree. They also looked at how ant and termite  colonies have evolved over time, and matched that data to the mammal diet stuff. Based on that, myrmecophagy does seem to be influenced by the availability of  ants and termites in the environment.

During the late Cretaceous, flowering  plants became much more abundant. This probably drove the explosion of  ant and termite colony populations, which then likely drove the evolution  of animals that can eat them. Maybe we should have called it the Cretaceous Anteater-ization Revolution, instead.

What do you mean “No”? In contrast, a lack of available  bugs probably pressured one myrmecophage lineage to  backtrack their ant-eating ways. Elephant shrews likely evolved  myrmecophagy about 55 million years ago, hence their super cute,  elongated snout and tongue.

This makes them one of the earliest  convergent evolvers of ant-eating. So it might sound a bit surprising  to hear they evolved out of it. Or at least a strict adherence  to that particular diet.

The scientists behind this paper  think that elephant shrews… who live mostly in the grasslands  and forests of southern Africa… evolved out of strict myrmecophagy in  response to the lack of bugs in the winter. Without the all-you-can-eat bug buffet, elephant shrews had to find something else to eat. Now, the little guys eat fruit as well as insects.

As far as this study could find,  they’re the only mammalian myrmecophages that reverted from their  previous anteater-ized fate. In comparison, crabs have unevolved  their crabby body plans enough times that scientists also have a name  for that: decarcinization. And it’s happened at least seven times.

I’d say that’s another point toward ant-eaters in this entirely pointless fight I’ve pitted. Okay, maybe not entirely  pointless, and not just because I really want to be served some  anteater memes alongside the crab ones. And for the record, they’ll stay memes, like this priceless piece of art we  asked our post-production team to create.

Your great-great-great-times-100  grandchild is almost definitely not going to end up looking like  the Vermilingua from Borderlands 3. Or a crab. We simply don’t have the genes for it.

Still, understanding how natural  selection creates hermit crabs and aardwolves can help scientists  apply those rules to other, perhaps more important matters. Like, say, antibiotic resistant bacteria. Or the next pandemic-causing virus.

Studying convergent evolution can help  scientists predict patterns of mutation, which is especially pertinent when researchers are trying to develop vaccines,  antibiotics, and so forth. Sounds pretty useful to me, even if we humans aren’t on track  to becoming anteaters ourselves. But if you’re suddenly feeling  hungry for a snack of ants on a log, I’m certainly not going to judge you. [♪ OUTRO]