Question

Briefly explain about water vascular system in echinoderms.  

Answer 1

The water vascular system is a hydraulic system used by echiniderms such as sea stars for locomotion, food and respiration. It's role in excretion is not ascertained. It acts as a sensory organ.System is composed of canals connecting numerous tube feet. It has following parts :

1- Madreporite / Sieve Plate : Water enters the vascular system

3- Ring Canal : surround mouth and leads to radial canals

3- Radial canals : 5 of them one down each arm

4- Ampulla : muscular sac that controls tube feet by forcing water into it.

5- Tube feet : Create suction to adhere to substrate

Tube feet may have suckers, allowing the echinoderm to move .while remaining firmly attached to the substrate -important in area with lots of wave action.

Water enters through the Madreporite. Then it is separated into five radial canals made of. Double rows of Ampulla. Ampulla are connecte to sucker like podia , the whole thing is called as tube feet.Contraction of Ampullae cause podia to move thus allowing overall locomotion