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.

Detailed explanation-2: -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.

Detailed explanation-3: -Water moves from the madreporite through the stone canal which leads to the ring canal. Water moves from the ring canal to the radial canals. The radial canals bring water to the tube feet. The tube feet are structures used for locomotion and capturing food (suction cup-like bottom).

Detailed explanation-4: -The water vascular system of the sea star consists of a series of seawater-filled ducts that function in locomotion and feeding and respiration. Its main parts are the madreporite, the stone canal, the ring canal, the radial canals, the lateral canals, and the tube feet.

Detailed explanation-5: -The madreporite is an essential part of the circulation system in echinoderms. Through this plate, which is also called a sieve plate, the echinoderm draws in seawater and expels water to fuel its vascular system. The madreporite functions like a trap door through which water can move in and out in a controlled manner.