HolothuroideaThe Holothuroidea, or sea cucumbers, are an abundant and diverse group of worm-like and usually soft-bodied echinoderms. They are found in nearly every marine environment, but are most diverse on tropical shallow-water coral reefs. They range from the intertidal, where they may be exposed briefly at low tide, to the floor of the deepest oceanic trenches. The oldest fossils of sea cucumbers are of spicules from the Silurian. Huge changes have occurred since then with about 1400 living species in a variety of forms. Some of these grow to about 20 cm in length, although adults of some species may not grow longer than a centimeter, while one large species can reach lengths of 5 meters. Several species can swim and there are even forms that live their entire lives as plankton, floating with the ocean currents.
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Kevin The Sea Cucumber > |
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Skeletal System
The Holothuroidea Sea Cucumber has a flexible body wall with circular and longitudinal muscles. It has a skeleton made up of isolated calcite particles called ossicles. The ossicles toughen the skin of the Sea Cucumber and show vestige of the normal skeleton. Usually a Holothuroidea is cylinder like, lying on its side. It has five rows of tube feet that go the length of the body. Around it's mouth there are two circles of feeding tentacles which are actually modified tube feet.
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