Madreporite

From Wikipedia, the free encyclopedia

Small red or yellow button-like structure that often looks like a small wart on a sea star's central disk. The madreporite is used to filter water into the sea star's water vascular system - a system of water filled canals and appendages that function primarily in locomotion, reproducing and feeding.

Water vascular system of the sea star consists of a series of seawater-filled ducts that function in locomotion and feeding. Main parts are the madreporite, the stone canal, the ring canal, the radial canals, the lateral canals, and the tube feet. The sieve-like madreporite allows entry of seawater into the stone canal, which connects to the ring canal around the mouth. Five radial canals extend form the ring canal, one in each arm above the ambulacral groove. From the radial canals extend many lateral canals, each of which leads to a tube foot. Each tube foot is a closed cylinder with muscular walls, having a sucker at the outer end and a bulb-like ampulla at its inner end within the body cavity.