what opens the water vascular system in sea stars?
madreporite
In sea stars, the water vascular system is a network of fluid-filled canals that enables them to perform various functions such as movement, feeding, and respiration.
The water vascular system in sea stars is opened by a specialized structure called the madreporite. The madreporite is a small, porous plate located on the aboral (upper) surface of the central disc of the sea star. It acts as a sieve or filter that allows water to enter the water vascular system.
Water enters the madreporite through the tiny pores in the plate and then flows into the stone canal, which is a channel that leads to the ring canal. The ring canal is a circular canal that surrounds the central disc and connects to the radial canals that extend out into the arms of the sea star.
Once inside the radial canals, water is pumped by the tube feet, which are small, suction-like structures that are used for locomotion and feeding. The water vascular system is also used for gas exchange and waste removal in sea stars.
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