Sea cucumbers are some of the strangest and least-known creatures in the world. They generally live in the deepest parts of the sea near coral reefs, but some species are found on beaches around the world.
Sea cucumbers are marine invertebrates, which means that they are invertebrates of the sea. The scientific word for sea cucumbers is Holothuroidea. They are also echinoderms, which in Greek means ¨spiny skin.” Some other cousins of the sea cucumber include: sea stars, sea pigs, sand dollars, and sea apples.
Sea cucumbers do not have brains, let alone faces, and they can come in all shapes and sizes. They can be as small as an inch long, or as large as ten feet. The largest sea cucumber ever recorded was about twelve feet long, or four meters.
There are roughly 1,250 species of sea cucumbers, and off the coast of China, there are over 40 recorded species roaming about. Some of the more common species are the sticky sea cucumber, which is shaped like a vegetable or fruit, or the ¨sea apple,” which is shaped like a peanut M&M and is very colorful.
Not only do sea cucumbers come in all shapes and sizes, but they also come in a wide variety of vibrant colors, such as purple, yellow, green, blue, pink, brown, black, and even translucent. Sea cucumbers can also light up at night, and will twist around in the water to attract attention. (They are not trying to mate; they just want others to see them.)
Sea cucumbers eat all sorts of things, including: algae, large bacteria, dirt or sand, and even their own snot. Even though it sounds gross, all these things give them nourishment to help them crawl around all day and night.
Arguably, the most interesting part of a sea cucumber is its butt. The sea cucumber has two anuses, one at each end of their body, and on either end of the body, inside of the anus, is something called ¨butt lungs.” Yes, you heard right. sea cucumbers expel waste and carbon dioxide out of the same place. Around their mouth (or anus, it doesn’t matter) they have tentacles that they clean their ¨mouth” with when they are done eating. Oh, and you thought we were done talking about butts; well, you are very wrong. Despite the grossness of a sea cucumber’s waste hole, small fish tend to find refuge inside of the sea cucumber’s anus and spend the day cleaning it.
Sea cucumbers communicate with each other by flinging out hormones into the water, and some sea cucumbers will wait for months until they get a response. A sea cucumber’s life span is about five to ten years.
When a sea cucumber wants to mate, they will twist around and sometimes even inflate to attract attention. Some sea cucumbers can reproduce asexually by splitting themselves in half to mate, and then those two halves go on and have separate lives. Sea cucumbers use a reproduction strategy called external fertilization in which the eggs are shot into the water and then fertilized.
Now while we think of cucumbers as gross and unsanitary, some animals, including large fish, eels, and even their own cousin, the sea star, find them tasty and will hunt them down. While sea cucumbers look useless, they have many defenses, including: liquifying themselves to get away from predators, shooting out sticky strings from their waste hole (and regrowing them), and believe it or not, firing their own intestines out at enemies to intoxicate them. Afterward, those regrow, too. Sea cucumbers are actually toxic, and while their toxin can not kill humans, it can make people ill and sometimes even unconscious. Sea cucumbers can also hide by burying themselves in the dirt or hiding in seagrass.
Sea cucumbers are a delicacy in China, and quite expensive, too, even though they are reported to have a bland taste. Luckily, sea cucumbers are not endangered; in fact, they are growing in population since most of their predators are being captured and killed as food. The seastar? Being kept as pets. Large fish? Being farmed and fed around the world.
There is so much more that humans can learn from these deep sea dwellers, and scientists around the world are finding out new facts about these sea cucumbers on a regular basis.