4. Illustrate the principal elements of the water-vascular system. Briefly discu

Question

4. Illustrate the principal elements of the water-vascular system. Briefly discuss the

multi-functional role(s) of this system among modern echinoderms. (2 points)

5. Echinoderms S. penta (Holothuroidea) is 40.0 cm on the longest axis of its body

whereas E. parma (Echionoidea) is 5.25 cm. After 1 week of starvation S. penta

was 30.0 cm and E. parma was 5.25 cm. After 2 weeks of starvation S. penta was

25.7 cm and E. parma was 5.24. After 3 weeks of starvation S. penta was 18.9

cm and E. parma was 5.25 cm. Provide, by diagram and brief discussion, an

adequate interpretation of these data. (2 points)

Explanation / Answer

The principal elements of water vascular system are canals connecting numerous tube feet. These are used for locomotion, food and water transportation and respiration.

The water vascular system provides the water pressure that operates on animal's tube feet. From the madreporite, water moves into the ring canal, then into the rays through radial canals and finally to the tube feet.The canals are like network of tube water pipes attached to the tube feet. Water also exits through the madreporite.

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