Sea cucumbers are sluggish, often brightly colored creatures with cylindrical or sausageshaped bodies. Yet, despite their unusual looks, they have many remarkable qualities.
Sea cucumbers belong to the large group of animals known as echinoderms (spiny-skinned animals) that includes the starfish and the sea urchins. Sea cucumbers are closely related to sea urchins. The sea urchins have a rigid outer skin, called a test, but the outer skin of sea cucumbers is not rigid. Instead, it is made up of chalky plates loosely set in a flexible body wall. The body wall has muscles that allow it to change shape. Three rows of tube feet run along the underside of the body and two run along the top. Tube feet are 
