Brittle star is a sea animal that resembles a starfish. Large numbers of brittle stars live along the bottom of all the world’s oceans and in shallow water near the shore. They are not often seen because they live under rocks or in cracks in coral, or they burrow in mud or sand.
There are thousands of species (kinds) of brittle stars. The center part of the animal, called the disk, is usually only about 1 1/5 inches (3 centimeters) across. The arms may be as long as 12 inches (30 centimeters). Most brittle stars have five arms. Some have six arms. Specialized brittle stars called basket stars have five arms that branch over and over again. The brittle star’s arms are longer and more flexible than those of starfish. Brittle stars are sometimes called serpent stars because their arms may resemble snakes. The brittle star is called “brittle” because it may throw off parts of its arms when it is handled or disturbed. Later, the arms grow back. The animal uses its arms to bring food to the mouth, which is in the center of the body on the underside. The mouth is the only opening into the brittle star’s saclike stomach. Unlike the arms of starfish, the arms of brittle stars do not have digestive or reproductive organs. The brittle star eats small animals that may be alive or dead.
The brittle star has slender tubes called tube feet on the underside of its arms. It uses them to breathe, to make small movements, to sense its surroundings, and to help bring food to the mouth. Unlike starfish, brittle stars have no suction disks on their tube feet.
