Anatomy

Luidia maculata, a seven armed starfish

Most starfish have five arms that radiate from a central disc, but the number varies with the group. Some species have six or seven arms and others have 10–15 arms.^[3]The Antarctic Labidiaster annulatus can have over fifty.^[4] Having descended from bilateral organisms, starfish move in a bilateral fashion, with certain arms acting like the front of the animal.^[3]