1 00:00:02,040 --> 00:00:07,000 Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff, 2 00:00:07,040 --> 00:00:10,239 Speaker 1: Lauren vocal bamb Here. You probably have a favorite sea 3 00:00:10,280 --> 00:00:13,960 Speaker 1: cucumber and don't even know it. There are over one thousand, 4 00:00:14,000 --> 00:00:16,680 Speaker 1: two hundred species in the world's oceans, so many that 5 00:00:16,760 --> 00:00:19,520 Speaker 1: scientists are even confused about exactly how many there are, 6 00:00:20,000 --> 00:00:22,959 Speaker 1: So there's probably one you'd like a lot. Some of 7 00:00:23,000 --> 00:00:24,800 Speaker 1: them are decked out with the colors of your favorite 8 00:00:24,800 --> 00:00:28,480 Speaker 1: sports team. Others look like somebody crocheted and oversized zucchini 9 00:00:28,520 --> 00:00:31,920 Speaker 1: out of brown aquylic yarn. Even if you weren't particularly 10 00:00:31,960 --> 00:00:34,720 Speaker 1: interested in a living sea cucumber, you might want to 11 00:00:34,760 --> 00:00:37,559 Speaker 1: eat a dead one, or even tape one is medicine. 12 00:00:38,040 --> 00:00:40,400 Speaker 1: But if you don't know already and had to guess, 13 00:00:40,600 --> 00:00:43,080 Speaker 1: would you bet a sea cucumber is an animal or 14 00:00:43,200 --> 00:00:46,599 Speaker 1: a vegetable. They tend to come in tube form, like 15 00:00:46,640 --> 00:00:50,199 Speaker 1: a sweet potato of the sea. They look vegetable ish, 16 00:00:50,280 --> 00:00:52,920 Speaker 1: but they are in fact animals. The thing where we 17 00:00:53,000 --> 00:00:56,760 Speaker 1: refer to them as cucumbers doesn't help. But they're a chinoderms, 18 00:00:56,880 --> 00:01:01,200 Speaker 1: a phylum of marine animals that also includes starfish sea urchins. 19 00:01:01,200 --> 00:01:04,959 Speaker 1: Everybody in this spylum has what's called pentameral symmetry. They 20 00:01:04,959 --> 00:01:08,479 Speaker 1: have five arms arranged around a center point. Of course, 21 00:01:08,720 --> 00:01:11,199 Speaker 1: the kindest thing you can say about a sea cucumber's 22 00:01:11,200 --> 00:01:13,240 Speaker 1: physique is that it looks like a large hogi bun 23 00:01:13,319 --> 00:01:15,960 Speaker 1: that you wouldn't want to eat. But though it more 24 00:01:16,000 --> 00:01:19,200 Speaker 1: closely resembles a slug than a star, the five rows 25 00:01:19,240 --> 00:01:21,440 Speaker 1: of tube feet that extend from its mouth to its 26 00:01:21,440 --> 00:01:24,360 Speaker 1: anus give it the same basic layout as say, a 27 00:01:24,560 --> 00:01:27,559 Speaker 1: very elongated sea urchin that fell over on its side. 28 00:01:28,200 --> 00:01:31,600 Speaker 1: Sea cucumbers have a different approach to reproduction than we do. 29 00:01:32,080 --> 00:01:34,640 Speaker 1: They are usually born either male or female, but can 30 00:01:34,760 --> 00:01:37,479 Speaker 1: change from one to the other during their lives. They 31 00:01:37,520 --> 00:01:40,199 Speaker 1: communicate with each other by releasing hormones into the water, 32 00:01:40,480 --> 00:01:43,360 Speaker 1: which is very similar to their style of reproduction. They 33 00:01:43,360 --> 00:01:45,880 Speaker 1: expel their gam meets those are the egg and sperm 34 00:01:45,920 --> 00:01:48,240 Speaker 1: cells out into the water column and just assume that 35 00:01:48,240 --> 00:01:50,520 Speaker 1: they'll find each other, just as they assume that their 36 00:01:50,520 --> 00:01:54,160 Speaker 1: friend got the hormone message that they left. Sea cucumbers 37 00:01:54,160 --> 00:01:57,440 Speaker 1: eat tiny animals, particles of algae, and general sea junk 38 00:01:57,440 --> 00:02:00,640 Speaker 1: out of the water using frilly tentacles that between meals, 39 00:02:00,680 --> 00:02:03,320 Speaker 1: they keep hidden in their mouths. What they have in 40 00:02:03,360 --> 00:02:05,000 Speaker 1: the way of a brain is a ring of nerve 41 00:02:05,040 --> 00:02:07,560 Speaker 1: cells around their mouth that tells them when it's time 42 00:02:07,560 --> 00:02:10,919 Speaker 1: to eat, burrow into the sand, walk somewhere, or attack. 43 00:02:11,560 --> 00:02:13,520 Speaker 1: And even though they look like tube socks filled with 44 00:02:13,560 --> 00:02:17,440 Speaker 1: modeling clay, a sea cucumbers defense mechanism is pretty terrifying. 45 00:02:18,120 --> 00:02:20,600 Speaker 1: Imagine you're rough housing with a friend or sibling, or 46 00:02:20,680 --> 00:02:23,480 Speaker 1: maybe taking a martial arts class. I'm willing to bet 47 00:02:23,560 --> 00:02:26,280 Speaker 1: that your opponent's defense mechanism would not be to shoot 48 00:02:26,320 --> 00:02:28,440 Speaker 1: out some of his respiratory organs at you out of 49 00:02:28,480 --> 00:02:32,200 Speaker 1: his rear. But that's what ce cucumber combat looks like. 50 00:02:32,520 --> 00:02:35,280 Speaker 1: They have the amazing ability to regenerate the organs that 51 00:02:35,320 --> 00:02:38,600 Speaker 1: they lose this way. Some species but out sticky string 52 00:02:38,639 --> 00:02:41,200 Speaker 1: like spiderwebs to trip up, or and snare their enemies, 53 00:02:41,360 --> 00:02:44,000 Speaker 1: while others have a special toxin that kills or stun 54 00:02:44,080 --> 00:02:48,560 Speaker 1: Small animals don't mess with sea cucumbers, but we do 55 00:02:48,639 --> 00:02:52,120 Speaker 1: mess with c cucumbers all the time. Some species are 56 00:02:52,120 --> 00:02:55,079 Speaker 1: at risk of extinction because in some Asian countries, sea 57 00:02:55,160 --> 00:02:59,120 Speaker 1: cucumbers are the ultimate luxury snack. Some tropical species can 58 00:02:59,120 --> 00:03:01,560 Speaker 1: go for between ten dollars and six hundred dollars per 59 00:03:01,639 --> 00:03:05,080 Speaker 1: kilogram dried in mainland China, and one type retails for 60 00:03:05,160 --> 00:03:08,880 Speaker 1: three thousand dollars per kilo. Sea cucumbers are also used 61 00:03:08,880 --> 00:03:11,280 Speaker 1: in Chinese medicine to treat a variety of ailments like 62 00:03:11,360 --> 00:03:15,959 Speaker 1: muscle aging, compromised immune system, fatigue, and arthritis. Some even 63 00:03:15,960 --> 00:03:18,959 Speaker 1: suggest they could be used in cancer treatments. The varieties 64 00:03:18,960 --> 00:03:21,400 Speaker 1: that are used in food or medicine are becoming increasingly 65 00:03:21,480 --> 00:03:26,560 Speaker 1: rare due to over fishing are over cucumbering. As a result. 66 00:03:26,600 --> 00:03:29,120 Speaker 1: There are around three hundred and seventy seven species of 67 00:03:29,120 --> 00:03:32,239 Speaker 1: sea cucumbers on the Red List of Threatened Species put 68 00:03:32,240 --> 00:03:35,640 Speaker 1: out by the International Union for Conservation of Nature. Seven 69 00:03:35,680 --> 00:03:38,640 Speaker 1: of these are classified as endangered and nine as vulnerable. 70 00:03:39,480 --> 00:03:42,880 Speaker 1: But we need sea cucumbers. Not only are they economically 71 00:03:42,920 --> 00:03:46,480 Speaker 1: important as a seafood, they are essential to ocean ecosystems. 72 00:03:46,680 --> 00:03:50,160 Speaker 1: They're important filtration systems for watery habitats all over the world. 73 00:03:50,560 --> 00:03:53,280 Speaker 1: In some places in the deep ocean, vast herds of 74 00:03:53,280 --> 00:03:56,520 Speaker 1: sea cucumbers roam the ocean floor, gobbling up to tritus 75 00:03:56,560 --> 00:04:00,640 Speaker 1: that drifted down from above. Plus some species provide vital 76 00:04:00,680 --> 00:04:04,040 Speaker 1: services for other marine life. The pearl fish, for instance, 77 00:04:04,040 --> 00:04:07,600 Speaker 1: takes refuge in a c cucumber's anus, and sometimes entire 78 00:04:07,680 --> 00:04:09,839 Speaker 1: schools of pearl fish can find shelter in the rear 79 00:04:09,920 --> 00:04:13,000 Speaker 1: end of a single ce cucumber. They usually don't mind 80 00:04:13,120 --> 00:04:15,680 Speaker 1: much unless they're trying to use their anus to breathe 81 00:04:15,760 --> 00:04:19,960 Speaker 1: at the moment. Oh yeah, c cucumbers breathe through their anuses. 82 00:04:20,160 --> 00:04:27,799 Speaker 1: I forgot to mention that part. Today's episode was written 83 00:04:27,800 --> 00:04:30,560 Speaker 1: by Jesselyn Shields and produced by Tyler Clay. For more 84 00:04:30,600 --> 00:04:33,040 Speaker 1: on this and lots of other bizarre topics, visit our 85 00:04:33,120 --> 00:04:46,400 Speaker 1: home planet, how Stuff Works dot com.