by Stefani Andrews

Created on: June 07, 2011   Last Updated: June 09, 2011

The sea cucumber is a very apt name for this echinoderm since that is precisely what the invertebrate looks like. This animal shares the class of echinoderm with other unusual sea creatures like sea urchin or starfish. They are a very large group of sea creature with 1,250 known species of sea cucumber. They are marine animals that have a long, muscular body that is covered by a leathery skin. Like all other echinoderms they have an

endoskeleton, which consists of calcified structures underneath the skin and are connected by connective tissue. In some species of sea cucumber these calcified structures resemble flattened plates that form an armor just under the skin. 

Sea cucumbers communicate with each other in a very strange way, they release hormone signals into the water that can then be sensed and interpreted by the other sea cucumbers in the area. While they do not have muscles in the traditional sense like a human does, they have catch collagen that forms their body wall and works with the connective tissue to create muscle like movement. This allows the sea cucumber to tighten or loosen this body wall at will and squeeze into tight spaces that it normally wouldn't fit into. Sea cucumbers use this as a defense mechanism, squeezing into rock crevices and then loosening this collagen body wall and anchoring themselves into place. Some species of sea cucumber have a very different way of defending themselves from predators. They can expel a sticky substance that is stored in their respiratory tubules that can entangle and confuse any potential predators. Expelling this substance does require disconnecting the tubules from the body as well, but these usually grow back in a few weeks' time. One of the chemicals in this tubule substance is holothurin, which shares a lot of similarities to soap. The chemical has been shown to kill any animal in the vicinity when it is released and is an excellent defense mechanism.

Sea cucumbers congregate on the sea floor, where they are usually the most numerous animal around, as much as 90% of the total biomass of the area. They tend to form herds and move together across the ocean floor in order to hunt for food. Sea cucumbers also have the ability to control their buoyancy and so they sometimes will hover slightly about the sea floor in order to move to a new location or maneuver around obstacles. Some types of fish have a symbiotic relationship with the sea cucumber, like the pearl fish. This fish will live inside

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