Echinodermata
Echinoderms are generally organisms with radial symmetry (all extremities meet at a central point), and several extremities extending from a central body. The body usually consists of five equal pieces, each containing an identical set of various internal organs. However Echinoderms possess no heart, brain, nor eyes, but some brittle stars seem to have light sensitive parts on their arms. Their mouth is located on the underside and their anus on top for the most part although there are a few exceptions.
Echinoderms have tentacle-like structures called tube feet with suction pads located at their extremities. These tube feet are controlled by an excellent vascular system. This system supplies water through channels of small muscular tubes to the tube feet. As the tube feet press against a moving object, water is withdrawn from them, resulting in a suction effect. When water returns to the channels, suction is released. The resulting movement is generally very slow.
Echinoderms have tentacle-like structures called tube feet with suction pads located at their extremities. These tube feet are controlled by an excellent vascular system. This system supplies water through channels of small muscular tubes to the tube feet. As the tube feet press against a moving object, water is withdrawn from them, resulting in a suction effect. When water returns to the channels, suction is released. The resulting movement is generally very slow.