GENERAL HISTOLOGY

Detailed explanation-1: -Sea stars have a water vascular system and tube feet much like those of the sea urchins. Ambulacral grooves (from the Latin root ambul meaning walk) are narrow channels in the oral surface of a sea star filled with tube feet. The tube feet are used mainly for grabbing and locomotion.

Detailed explanation-2: -All echinoderms have unique hydraulic structures called tube feet, known for their roles in light sensitivity, respiration, chemoreception and locomotion.

Detailed explanation-3: -Asteroids and echinoids, which use spines and tube feet in locomotion, may move forward with any area of the body and reverse direction without turning around. The feet may be used either as levers, by means of which the echinoderm steps along a surface, or as attachment mechanisms that pull the animal.

Detailed explanation-4: -It is these suction-bottomed tubes that the sea star uses to move about. It draws in water and channels it to canals that run throughout its body, usually ending in the tube feet. By changing the pressure of water in its body, the sea star can move the tubed feet, and thus move forward.