Found only in salt water, thousands of species of sea cucumbers, or Holothuroidea, exist all around the world. Despite popular belief, they are not a type of marine plant! They are, however, harvested regularly in Asia, or even raised in captivity, for human consumption. That being said, here are five facts you probably did not know about the sea cucumber.
Number Five: They Don’t Have Brains. Instead of brains, sea cucumbers have a ring of nervous tissue surrounding their mouth, which sends nerve signals to trigger movement and eating behaviors. Considering those are the two things required for the sea cucumber to live, that makes the nervous tissue ring seem like a primitive brain. If this ring is surgically removed, however, the sea cucumber can still move and eat perfectly fine. Try removing your brain and still being able to eat and walk!
Number Four: They Breathe Through Their Butts. Like most marine animals, sea cucumbers use oxygen from the water. The sea cucumber, however, uses a pair of respiratory trees that branch off the cloaca, just inside the anus. They then “breathe” by drawing in water through their anus, and they then expel the used water back out. Thank goodness they do not also smell through their anus.
Number Three: They Comprise the Majority of Deep Sea Biomass. At a depth of 8.9 km (5.5 miles), sea cucumbers comprise 90% of the total mass of macrofauna (invertebrates that live on or in sediment) in the ocean. They often form large herds that move across the sea floor, hunting food. There have been documented cases of whale carcasses being devoured by a herd of sea cucumbers in a month. Imagine how many sea cucumbers it would take to devour 26 tons of flesh in one month!
Number Two: They Are Used in Asian Folk Medicine. Though there is no reliable scientific evidence that sea cucumbers are effective in treating cancer, arthritis, and other ailments, there are pharmaceutical companies looking into the possibilities. One study found that in mice, high doses of sea cucumber extract reduced internal pain. Another study suggests that sea cucumbers contain all the fatty acids that play a role in tissue repair, which has spurred research to use sea cucumbers as an agent to fight colon cancer. Maybe there is some truth to ancient Chinese holistic medicine.
Number One: Their Defense Display Is Truly Terrifying. If you ever sneak up on a sea cucumber, be prepared for a mess. Some species shoot sticky threads from their mouths in order to confuse and entangle predators (or your hand). Others, however, are capable of violently contracting their muscles and expelling some of their internal organs out of their anus, for the same purpose. Both strings and organs are quickly regenerated by the sea cucumber’s body. Wow…and yuck!