WEBVTT - What Are Sea Cucumbers?

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<v Speaker 1>Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

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<v Speaker 1>Lauren vocal bamb Here. You probably have a favorite sea

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<v Speaker 1>cucumber and don't even know it. There are over one thousand,

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<v Speaker 1>two hundred species in the world's oceans, so many that

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<v Speaker 1>scientists are even confused about exactly how many there are,

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<v Speaker 1>So there's probably one you'd like a lot. Some of

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<v Speaker 1>them are decked out with the colors of your favorite

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<v Speaker 1>sports team. Others look like somebody crocheted and oversized zucchini

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<v Speaker 1>out of brown aquylic yarn. Even if you weren't particularly

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<v Speaker 1>interested in a living sea cucumber, you might want to

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<v Speaker 1>eat a dead one, or even tape one is medicine.

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<v Speaker 1>But if you don't know already and had to guess,

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<v Speaker 1>would you bet a sea cucumber is an animal or

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<v Speaker 1>a vegetable. They tend to come in tube form, like

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<v Speaker 1>a sweet potato of the sea. They look vegetable ish,

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<v Speaker 1>but they are in fact animals. The thing where we

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<v Speaker 1>refer to them as cucumbers doesn't help. But they're a chinoderms,

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<v Speaker 1>a phylum of marine animals that also includes starfish sea urchins.

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<v Speaker 1>Everybody in this spylum has what's called pentameral symmetry. They

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<v Speaker 1>have five arms arranged around a center point. Of course,

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<v Speaker 1>the kindest thing you can say about a sea cucumber's

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<v Speaker 1>physique is that it looks like a large hogi bun

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<v Speaker 1>that you wouldn't want to eat. But though it more

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<v Speaker 1>closely resembles a slug than a star, the five rows

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<v Speaker 1>of tube feet that extend from its mouth to its

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<v Speaker 1>anus give it the same basic layout as say, a

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<v Speaker 1>very elongated sea urchin that fell over on its side.

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<v Speaker 1>Sea cucumbers have a different approach to reproduction than we do.

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<v Speaker 1>They are usually born either male or female, but can

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<v Speaker 1>change from one to the other during their lives. They

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<v Speaker 1>communicate with each other by releasing hormones into the water,

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<v Speaker 1>which is very similar to their style of reproduction. They

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<v Speaker 1>expel their gam meets those are the egg and sperm

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<v Speaker 1>cells out into the water column and just assume that

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<v Speaker 1>they'll find each other, just as they assume that their

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<v Speaker 1>friend got the hormone message that they left. Sea cucumbers

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<v Speaker 1>eat tiny animals, particles of algae, and general sea junk

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<v Speaker 1>out of the water using frilly tentacles that between meals,

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<v Speaker 1>they keep hidden in their mouths. What they have in

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<v Speaker 1>the way of a brain is a ring of nerve

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<v Speaker 1>cells around their mouth that tells them when it's time

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<v Speaker 1>to eat, burrow into the sand, walk somewhere, or attack.

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<v Speaker 1>And even though they look like tube socks filled with

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<v Speaker 1>modeling clay, a sea cucumbers defense mechanism is pretty terrifying.

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<v Speaker 1>Imagine you're rough housing with a friend or sibling, or

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<v Speaker 1>maybe taking a martial arts class. I'm willing to bet

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<v Speaker 1>that your opponent's defense mechanism would not be to shoot

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<v Speaker 1>out some of his respiratory organs at you out of

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<v Speaker 1>his rear. But that's what ce cucumber combat looks like.

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<v Speaker 1>They have the amazing ability to regenerate the organs that

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<v Speaker 1>they lose this way. Some species but out sticky string

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<v Speaker 1>like spiderwebs to trip up, or and snare their enemies,

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<v Speaker 1>while others have a special toxin that kills or stun

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<v Speaker 1>Small animals don't mess with sea cucumbers, but we do

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<v Speaker 1>mess with c cucumbers all the time. Some species are

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<v Speaker 1>at risk of extinction because in some Asian countries, sea

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<v Speaker 1>cucumbers are the ultimate luxury snack. Some tropical species can

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<v Speaker 1>go for between ten dollars and six hundred dollars per

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<v Speaker 1>kilogram dried in mainland China, and one type retails for

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<v Speaker 1>three thousand dollars per kilo. Sea cucumbers are also used

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<v Speaker 1>in Chinese medicine to treat a variety of ailments like

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<v Speaker 1>muscle aging, compromised immune system, fatigue, and arthritis. Some even

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<v Speaker 1>suggest they could be used in cancer treatments. The varieties

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<v Speaker 1>that are used in food or medicine are becoming increasingly

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<v Speaker 1>rare due to over fishing are over cucumbering. As a result.

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<v Speaker 1>There are around three hundred and seventy seven species of

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<v Speaker 1>sea cucumbers on the Red List of Threatened Species put

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<v Speaker 1>out by the International Union for Conservation of Nature. Seven

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<v Speaker 1>of these are classified as endangered and nine as vulnerable.

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<v Speaker 1>But we need sea cucumbers. Not only are they economically

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<v Speaker 1>important as a seafood, they are essential to ocean ecosystems.

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<v Speaker 1>They're important filtration systems for watery habitats all over the world.

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<v Speaker 1>In some places in the deep ocean, vast herds of

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<v Speaker 1>sea cucumbers roam the ocean floor, gobbling up to tritus

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<v Speaker 1>that drifted down from above. Plus some species provide vital

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<v Speaker 1>services for other marine life. The pearl fish, for instance,

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<v Speaker 1>takes refuge in a c cucumber's anus, and sometimes entire

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<v Speaker 1>schools of pearl fish can find shelter in the rear

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<v Speaker 1>end of a single ce cucumber. They usually don't mind

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<v Speaker 1>much unless they're trying to use their anus to breathe

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<v Speaker 1>at the moment. Oh yeah, c cucumbers breathe through their anuses.

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<v Speaker 1>I forgot to mention that part. Today's episode was written

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<v Speaker 1>by Jesselyn Shields and produced by Tyler Clay. For more

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<v Speaker 1>on this and lots of other bizarre topics, visit our

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<v Speaker 1>home planet, how Stuff Works dot com.