Hobbies And Interests
Class Holothuroidea
Within the phylum Echinodermata, 1,400 species of sea cucumbers comprise the class Holothuroidea. As one might expect, most are approximately the size and shape of cucumbers, although the largest species can reach 16 feet or more in length. Others are quite tiny. They are found in virtually all marine environments, from shallow intertidal zones to deep sea trenches. Many are bottom-feeding scavengers, filling a role similar to earthworms. But there are some who live their entire lives as drifting plankton.
Common Edible Species
Some species of sea cucumbers are edible. Cut, rinsed and dried, they are sold in many parts of the world, particularly Asia, as "trepang" or "beche-de-mer." According to the United Nations Food and Agriculture Organization, there are 66 economically important species of sea cucumber, most of which are harvested for food. The common names of most of these species can be misleading, because sea cucumbers are invertebrates and not fish. They include sandfish, redfish, stone fish, flower fish, lollyfish, snakefish, teatfish, elephant trunk fish, curry fish and donkey dung. Perhaps the only sea cucumber that is not named for something else is the pentard.
Aquarium Species
Two of the species identified by the FAO as economically important are in demand as aquarium pets. They are known popularly as the Indonesian sea apple and the Australian sea apple. Quite unlike apples, but very much like ladybugs, monarch butterflies and many other conspicuously-colored creatures, sea apples advertise to potential predators that they contain nasty and foul-tasting toxins, and that eating them would be a mistake. In fact, many sea cucumber species produce toxins, and are of considerable interest to pharmaceutical researchers for just this reason.
Deep Sea Species
Apart from the readily accessible food species and their glamorous aquarium features, there are more than 1,000 other kinds of sea cucumbers in the oceans of the world that play vitally important roles in marine ecosystems. In some parts of the deep sea, sea cucumbers account for 90 percent of the biomass. Here can also be found pelagic sea cucumbers, the only echinoderms that swim rather than merely crawling along the bottom. Some, like Enypniastes, even resemble jellyfish as they gracefully ply their way through the depths.