GENERAL HISTOLOGY

Detailed explanation-1: -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.

Detailed explanation-2: -Locomotion: Sea stars move using a water vascular system. Water comes into the system via the madreporite. It is then circulated from the stone canal to the ring canal and into the radial canals. The radial canals carry water to the ampullae and provide suction to the tube feet.

Detailed explanation-3: -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-4: -The madreporite /ˌmædrɪˈpɔːraɪt/ is a light colored calcareous opening used to filter water into the water vascular system of echinoderms. It acts like a pressure-equalizing valve.

Detailed explanation-5: -The components of the water vascular system of echinoderms. Water enters the system through the madreporite, flows through the stone canal, and enters the ring canal. A number of bulbous structures, called polian vesicles, that branch off of the ring canal serve as reservoirs to maintain extra water stores.