GENERAL HISTOLOGY

Detailed explanation-1: -The inner wall of the water vascular canals are provided with cilia. The beating of the cilia causes the seawater to enter through the madreporite. Finally, the seawater reaches the tube feet and their ampullae.

Detailed explanation-2: -The madreporite is a light-colored, calcerous opening used to filter water into the water vascular system of echinoderms. Acting as a pressure-equalizing valve, it is visible as a small red or yellow button-like structure (similar to a small wart) on the aboral surface of the central disk of a sea star.

Detailed explanation-3: -The madreporite is a sieve-like, calcified plate that connects the system to the aquatic environment. Water enters through the madreporite and flows through a tube, called the stone canal, that connects to the circular ring canal surrounding the mouth.

Detailed explanation-4: -The water vascular system is an important character in the echinoderms as the organisms reside in the aquatic environment. Water enters the vascular system through a structure known as madreporite. This is the structure through which echinoderms take in seawater and also expels the water outside the system.

Detailed explanation-5: -In sea stars, water enters the system through a sieve-like structure on the upper surface of the animal, called the madreporite. This overlies a small sac, or ampulla, connected to a duct termed the stone canal, which is, as its name implies, commonly lined with calcareous material.