The cellular construction of sponges consists of an outer layer of covering cells and an inner layer of flagellated cells that move water through the animals. Sponges feed by moving water into pores called ostia and then out a large topmost opening called the osculum. Each flagellated cell has a thin collar around a single flagellum. These cells line either large chamber or small ones called flagellated chambers. Starfish A starfish is not a fish.
Most starfish have five arms, but some have more.
If a starfish loses an arm, a new one will grow in its place. If a starfish is cut in half, each half will become a new starfish. Each starfish arm is lined with tube feet. At the end of each tube foot is a sucker. These suckers help the starfish move.