Chapter 29, Problem 9STP

Summary Introduction

To write:

The name each of the numbered structures and describe how they enable a sea star to move.

Introduction:

Echinoderms are marine creatures, including sea stars, sea urchins, brittle stars, sea urchins, sea lilies, sea cucumbers and sea urchins. Echinoderms are deuterostomes because their mouth differs from the rest of the gastrointestinal tract. Till now almost 6000 living species of echinoderms have been identified.

Explanation of Solution

In the given diagram, the number 1 refers to central canal, 2 refers to radial canal, 3 refers to ampulla, 4 refers to tube feet, and 5 refers to madreporite. Tube feet are small flexible, fluid-filled tubes that end up in suction cup-like structures and are used for movement, food collection and respiration. The opposite end of the tube leg is a muscular sac named an ampulla. As the muscles contract in the ampulla, the water is pushed into the foot of the tube and spreads. It is connected to the surface by the suction cup-like structure at the end of the tube foot. This hydraulic suction allows all of the echinoderms to move.

Conclusion

Thus, the sea stars can move with the help of tube feet and ampulla.