How do sea stars move?
Sea stars move by tube feet on their oral surface. Internally sea stars have little bulbs called ampullae running along each arm. The ampullae are small fluid filled sacs that contract and allow tube feet on the exterior to elongate by pushing fluid into them. The tube feet are hollow and very muscular with suckers at the end. When the tube foot is touching a substrate muscles can raise the center disc and form suction. Muscles on the sides of the tube feet can be contracted and cause movement in that direction.
