Sea cucumbers have evolved to lie on one side with the mouth and anus on opposite ends of the body. Their skeletons have been reduced to microscopic ossicles which are important in identifying species. Sea cucumbers feed by means of filtering suspended food particles or organic laden sediments using their feeding tentacles. They thus play an important role in helping to turn over reef sediments.
Holothuria leucospilota is one species I’ve encountered numerous times. They are usually exposed at low tide and are conspicuous in rock crevices. They kind of look like the excrement of a giant marine creature.
H. leucospilota is one of the species that ejects sticky white threads called Cuvierian tubules from the anus as a defence strategy. The repugnant tubules are believed to repel or entangle would be predators.
Sea cucumbers may be soft bodied and appear docile but they are not to be underestimated!
Pictures taken at: Terumbu Bukom, July 2006; St John’s Island, December 2006 and Lazarus Island, December 2006.
Colin, P. L. & C. Arneson, 1995. Tropical Pacific Invertebrates. A Field Guide to the Marine Invertebrates Occurring on Tropical Pacific Coral Reefs, Seagrass Beds and Mangroves, Coral Reef Press, U.S.A.
Lane, D. J. W. & D. Vandenspiegel, 2003. A Guide to Sea Stars and other Echinoderms of Singapore, Singapore Science Centre, Singapore.