Brittle stars, which are sometimes called serpent stars, are long-armed, spiny animals that live on the sea floors, disregarding its depth. Brittle stars are not fish, but are related to starfish. These animals without back bones, cold-blooded, with their temperature depending on the temperature of the environment, move slowly along the ocean floor. Most brittle stars have the following physical characteristics: spiny, long arms that do not intercept at their bases, flat central disk which is the origin of the arms, hard exoskeleton, and approximately one inch in diameter. Brittle stars have an ability to regenerate their legs if it was cut off or damaged. Due to the fact that these animals do not have brain, information flows around the body by means of a simple ring of nerve cells. Light and smells are sensed by tube feet situated on the arms. Plankton and decomposing matter are the main constituents of their diet.