Question

Give an account of structure and function of the water vascular system in echinoderms

Answer 1

Water vascular system is one of the most distinctive feature of echinoderms which helps in locomotion, capture and transport of food and respiration.
Water vascular system is made of tubes or channels connected to numerous tube feet. The exchange of gases occurs through the body surface and tube feet. The oxygen enters the water vascular system from atmosphere that distributes it throughout the body in echinoderms. The carbon dioxide from tissues again enters the water vascular system which transports it to body surface for removal from body. This way, it helps in respiration.

Hope this information will clear your doubts about the water vascular system of echinoderms.

Answer 2

$\text{\underline{\underline{Structure\:of\:water\:vascular\:system:}}}$


⚫The water-vascular system consists of a performed plate called madreporite the pores of which allow the sea water to enter into the system.


⚫From the madreporite starts stone canal which opens into the ring canal.


⚫From each angle of ring canal arises radial canal which runs through the length of each arm.


⚫From radial canal arise lateral canals which end in tube feet. The tube feet are the tube-like appendages. There are two double rows of tube feet in each arm, one double row in relation to each series alternatively placed long and short lateral canals.


⚫Each tube foot can be distinguished into three regions:

(i) A round sac-like ampulla.

(ii) A middle tubular podium.

(iii) A cup-like sucke* at the lower end of podium.


$\text{\underline{Example:}}$ Starfish