This system follows the same five-armed arrangement which occurs in all echinoderms. This starfish can be divided into three groups. There are the brittle stars, which break off their long snaky rays if they are caught. Their arms may extend 20 to 25 centimeters. Then there are the feather stars, whose waving rays resemble little feathers. And there are the ordinary sea stars which usually measure about13 centimeters.
The tough, leathery skin of a starfish is covered with very short spines. In the center of their bodies are disk-like buttons. Through these disks they draw in or push out sea water. The disks on the underside act as mouths. The eyes are at the tips of their arms and are protected by a circle of spines.
Starfish can also eat by taking food into their mouths in the ordinary way. They can also replace broken arms. In fact, they may even grow a whole new body from one arm. There should be at least on starfish in Ripley’s “Believe it or not” museum!