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All animals have adaptations that help them survive in the wild...some just focus more on back-end development than others. Whether for offense, defense, or both, here are five creatures with butt-kicking behinds!
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[♪ INTRO].

If you’ve been around the internet long enough, you might have discovered that  wombat butts are pretty cool. I mean, they produce cube-shaped poop!

You may have also heard that  wombats can use their rear-ends to crush the skull of any predator  who wanders into their burrow. Unfortunately, the stories of wombat  combat seem to be unconfirmed. But the idea of a tactical  butt does have some merit.

It turns out, there are many critters with offensive and defensive  derrieres — including these five. First, dragonfly larvae. Dragonflies are master predators.

They’re sometimes called the most  successful hunters in the animal kingdom, because they can catch up to 95  percent of their intended prey. And their babies are no joke, either. Dragonfly larvae are also called nymphs.

They live underwater, and to  breathe, they don’t use their mouths. Instead, they draw in water  through their anus into a large, muscular hindgut chamber,  where they extract oxygen from it. So, this butt kind of does everything.  It breathes, it digests, it poops.

And it even acts like an engine. By suddenly squeezing water out of their  hindguts, dragonfly larvae can create powerful jets that rocket them around  underwater and help them avoid danger. They can even use their hindguts  to supercharge their mouths.

See, these little assassins have specialized  mouthparts that can shoot out in a fraction of a second and grab fast-moving  prey, kind of like a chameleon’s tongue. But the thing is, their mouths don’t  have a muscle large and powerful enough to shoot their jaws out like that. So, instead, the nymphs use hydraulic  pressure — from their rear ends.

First, the larvae pull back their  mouthparts like they’re cocking a gun. Then, they seal shut their anal  valve, and squeeze their hindgut. The water pressure builds  and builds inside of them.

And eventually, a special mechanism  in the mouthparts releases, discharging some of the internal pressure  and rocketing their mouth forward. This method allows the insects  to capture quick-moving prey even through the drag of water. Plus, they don’t have to load up  their mouths with giant muscles that would weigh them down.

So they  can keep their arsenal light and fast. Another critter with a  remarkable rear is the scorpion. Now, scorpions are famous for their  stingers, which inject venom into their prey.

But stingers are not butts. In fact, they’re  not even part of the digestive tract. Still, some scorpions do have a  legitimate rear-end-related skill.

And they use it for defense. Specifically, they have  disposable, sacrificial butts. Researchers have found that 14 species in  South America can break their tails off to avoid capture, a behavior called autotomy.

Some species of lizards can famously  do this with the tips of their tails. And some spiders can do it with their legs. Why?

Well, sacrificing part of  yourself can let you distract predators or escape from them. I mean, it’s a super costly  strategy, but it’s better than dying. So, when threatened, these South American  scorpions can drop their stingers and other segments of their  tails for a quick getaway.

But here’s the catch: They also drop the  part of their tail that contains their anus. When this happens, the wound heals  over, but the anus doesn’t regenerate. That means they can’t get rid of waste.

So the end result is that the scorpions  inevitably die from... fatal constipation. Now, if there’s a silver lining here,  it’s that scorpions don’t poop that much. In fact, in the lab, it took up to eight months  for constipation levels to become critical.

The researchers suggest this  may be more than enough time for the animals to mate and  carry on their genetic line — which might explain why this  trait hasn’t evolved away. After all, natural selection generally only cares whether you successfully have babies. And if the anus-less  scorpions can still reproduce… well, from an evolutionary perspective,  it doesn’t matter what happens after that.

Speaking of bum deals, sea cucumbers  have to put up with some problems that are literally a pain in the butt. In general, these odd critters  may seem pretty unassuming, but they have a number of tricks  up their posterior sleeve. Like, when in danger, sea cucumbers  may eviscerate themselves, throwing their intestines out  their anuses at predators.

This is a kind of autotomy,  like what scorpions do. And while intestine hurling may be a  distraction, it can also drive predators off, since sea cucumbers’ guts may contain  noxious chemicals or adhesive tubules. Luckily, sea cucumbers can regenerate those bits.

And that’s also not the weirdest  thing about their backsides. Some species also come equipped  with spines called anal teeth. You see, slender, wriggly animals  called pearlfish have a habit of swimming inside sea cucumber  butts to hide from predators.

Like, sometimes, several pearlfish  shelter in one sea cucumber’s caboose. In many cases, the sea cucumbers  aren’t really harmed by the fish. But sometimes, while the  pearlfish are hanging out there, they do pick out a nice snack for  themselves: the sea cucumber’s gonads.

Like we said, sea cucumbers  can regenerate their organs, but having your gonads eaten  probably isn’t pleasant. Now, you might think sea  cucumbers could just, like, clench up if suspicious fish are  hovering around their hindquarters. But here’s the thing: Like dragonfly nymphs, many species of sea cucumber  also breathe through their butts.

Which means they have to open up at some point, giving fish an opportunity to  wriggle where they’re not wanted. So, these spiky, anal teeth allow  sea cucumbers to breathe easy while preventing pearlfish from  swimming in their deep ends. Next up, rove beetles.

One of the most common ways butts are weaponized is through noxious secretions or sprays. These smelly or irritating chemicals may come from a creature’s digestive tract or nearby glands. Many species use them as deterrents.  Think skunks or bombardier beetles.

And if we went through each of them,  this List Show would be hours long. But rove beetles take backside  chemical bombs to the next level. These beetles can use their butts  for both attack and defense.

For example, one water-skimming  beetle group uses its butt to surf. These beetles live in aquatic  environments and are light enough to stand on the surface of the water.  But when a predator appears, they need to make a quick escape. You might expect them to just paddle  their little feet as fast as they can.

But instead, they secrete a  hydrophobic liquid from their butt and drop it onto the surface of the water. The secretion breaks up the water tension, which is the force that causes  water to naturally stick together. Normally, the tension would pull on all sides of the bug at the same  time, making it stand still.

But by disrupting the tension behind them, the only tension acting on the  beetle is toward the front. This unequal force causes  the bugs to rocket forward, like a surfer who makes their own  waves, and speed away from danger. Escaping danger is the typical reason  for producing nasty butt secretions.

But what’s special about rove beetles is  that there may be at least one species that uses secretions as a lure. Now, we should caveat that this part  seems to have come from a single report. That’s to say, one group described something without another group following up on it.

That doesn’t mean they’re wrong. When we  reached out to a scientist about this, they pointed out that these kinds of rare  observations can be hard to follow up on. But it is kind of a gap in the system.

So, you know, grad students, if  you’re looking for ideas for your PhD…. Anyway, in the tropical forests  of Central and South America lives a rove beetle that only eats flies. And flies can be hard to catch.

They  can, as their name implies, fly. So sometimes, the beetle hides  near the flies’ favorite foods, like rotting fruit, poop, and dead animals. Then, when the flies come to  feast, the beetles ambush them.

However, if no obvious fly lures are  around, the beetles seem to make their own. In the 1990s, a pair of scientists  reported that when these rove beetles couldn’t stake out any poop  or dead animals or whatnot, they perched on leaves or rocks  and lifted their butts in the air. Then, glands on those upturned  rears released a secretion that appeared to attract flies.

The flies seemed so enticed that  they didn’t even notice or care when the beetle started moving into a  striking position — until it was too late. If this is true, it’s a  remarkable evolutionary adaptation that makes getting food much  more reliable for the beetles. But the scientists don’t know what compound  the beetles use to attract the flies.

So the bottom line is: This  mystery needs a follow-up. Finally, we leave you with an honorable  mention in this rump-tastic roundup. Like the rove beetle lures, it’s based on  a single report that is yet to be repeated.

But it’s pretty remarkable if true. In the 1980s, there was a report  that the larvae of beaded lacewings could use their butts to attack and  paralyze prey... by farting on them. In that paper, researchers reported that  they saw termite-eating lacewing larvae approach termites, then lift up their butts  and wave them past the termite’s face.

After a few minutes, the  termites became paralyzed, whereupon the larvae began to feed. Investigating a bit more, the  researchers concluded that the weapon must be a gas...a truly toxic fart! And this could be a useful  tactic because the termites are actually much larger than the larvae.

So it’s kind of a David and Goliath situation,  and the larvae needed to get creative. This would represent the  only known case of a chemical being used to attack like this. But again,  researchers need to investigate this further.

Really, in the end, these examples show  that scientists need to do a lot more research into the remarkable,  versatile, and under-appreciated butt. Not because it makes a good joke, but  because rear ends can genuinely have some extremely clever, unexpected adaptations that teach us more about  life in the animal kingdom. And that is something we can all get behind.

If you liked this episode, well,  we’ve got a special treat for you. Every month on our Patreon, we release a… let’s just call it a “potentially  not safe for work” podcast. It’s called SciShow After Hours, and it’s where Hank and one of our  editors get together to talk about some fascinating science we just  couldn’t put on this channel.

If you want to learn more about it, you  can head over to [♪ OUTRO].