Answer:
Tube feet in echinoderms have a few functions. The obvious one is locomotion. The feet are powered by the water vascular system. They are also important for absorbing oxygen (remember that the body of sea stars and their relatives are covered in bony plates called ossicles), for eliminating nitrogenous waste products of metabolism, and grasping prey. Sea stars are capable of pulling a bivalve apart by exerting pull on the two shells and essentially tiring the prey out as the muscles the prey eventually tire. Once there is an opening, the sea star everts its stomach into the prey.
If you've ever picked up a sea star and turned it over, you probably noticed the hundreds of tube "feet" lining its arms. 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.
Tube feet function in locomotion, feeding, and respiration. The tube feet in a starfish are arranged in grooves along the arms. They operate through hydraulic pressure. They are used to pass food to the oral mouth at the center, and can attach to surfaces.
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