Any of various marine echinoderms of the class Asteroidea, having a star-shaped body usually with five arms. The arms have rows of little suckers on the undersides, called tube feet, with which the animal moves around and grasps prey. Many species extrude their stomach onto prey and digest it externally. Starfish can grow new arms if any are lost, and in one species, a whole individual can be regenerated from a single piece of arm. Starfish are related to sea urchins and sea cucumbers.