sieve plate; small porose button on upper or aboral surface of the body ring of starfish, through which the water vascular system connects with the exterior.
The porous opening to the hydrocele in echinoderms.
a structure located on the aboral surface, in some species looking rather like a drain cover in a sink. The madreporite is a perforated platelike structure which acts as the inlet for the water vascular system.
Small red or yellow button-like structure that often looks like a small wart on a starfish'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.