00:00:03 – Sea cucumbers have a really strange relationship with their buttholes.
00:00:06 – I’m Anna Rothschild, and this is Gross Science.
00:00:12 – To begin, let me just clarify that sea cucumbers don’t exactly have a b*** in the human sense.
00:00:18 – They have something called a “cloaca” which is kind of an all-purpose opening.
00:00:23 – Lots of animals, including many birds, have a cloaca, which they use to pee, p***, and
00:00:29 – in some cases, mate.
00:00:30 – But the sea cucumber takes this whole “all-purpose” thing a little further.
00:00:35 – To begin with, they actually breathe through their butts.
00:00:39 – Rather than using lungs, sea cucumbers take in oxygen by flushing water over organs called
00:00:44 – respiratory trees.
00:00:46 – And how does the water get into the sea cucumber?
00:00:48 – It’s pumped in through the backdoor by the muscles of the cloaca.
00:00:53 – Sometimes bits of food get pumped in, too.
00:00:56 – And at least some sea cucumbers don’t let those bits go to waste—they can eat with
00:01:02 – their butts, as well!
00:01:03 – Their respiratory trees possess some intestine-like properties, and can absorb nutrients.
00:01:09 – To be clear, sea cucumbers probably prefer to eat with their mouths.
00:01:13 – But they won’t turn down a tasty morsel if it happens to float in through the cloaca.
00:01:18 – Finally, and perhaps strangest of all, small skinny fish called pearlfish actually make
00:01:25 – sea cucumber butts their home.
00:01:28 – Many pearlfish live peacefully with their sea cucumber hosts.
00:01:32 – They’re what’re called “inquilines,” which means that they’re organisms that
00:01:36 – live inside of or in the home of another species, but don’t hurt it.
00:01:41 – However, some species of pearlfish are actually parasitic and eat the sea cucumber’s reproductive
00:01:47 – organs along with other tissue.
00:01:50 – Now, sea cucumbers actually have a bunch of defense mechanisms to avoid predators and
00:01:56 – parasites.
00:01:57 – One is the ability to expel and regenerate their internal organs—and for more on that,
00:02:02 – see my previous video on the subject.
00:02:04 – But they also have chemicals called saponins in their bodies, including in their Cuvierian
00:02:09 – tubules, which are sticky strings that sea cucumbers shoot out of their cloaca when they’re
00:02:15 – attacked.
00:02:16 – Saponins usually burst open the cells of the would-be predator or parasite.
00:02:21 – But pearlfish aren’t affected.
00:02:23 – And scientists think it might be because they’re covered in a relatively thick layer of mucus,
00:02:28 – which protects them from the toxins.
00:02:30 – As a side note, Harlequin crabs, which also live in and on sea cucumbers, may actually
00:02:35 – be attracted to their hosts by those same chemicals.
00:02:39 – Finally, sea cucumbers may have one more defense mechanism.
00:02:43 – Some of them have structures called a*** teeth, possibly to keep the pearlfish out—though,
00:02:48 – no one knows for sure if that’s really what a*** teeth are for.
00:02:51 – In many species, the fish can slip in anyway.
00:02:54 – Long story short, sea cucumbers are really just gifts to curious people everywhere.
00:02:59 – The more I learn, the more I’m impressed with these guys…and with their butts.
00:03:10 – Ew.