Chapter 27, Problem 37A

Summary Introduction

To write:

About the arms of echinoderms that reflect in the given diagram

Introduction:

Echinoderms are marine animals with spiny endoskeletons, water-vascular systems, and tube feet; they have radial symmetry as adults. Echinoderms are deuterostomes. The approximately 6000 living species of echinoderms are marine animals and include sea urchins, sea stars, and sand dollars, sea cucumbers, brittle stars, sea lilies and feather stars, and sea daisies.

Explanation of Solution

All echinoderms have radial symmetry as adults. Echinoderms are characterized by radial symmetry, with many arms (5 or more) from a central body radiating out. When a starfish loses one arm from five arms, it has the capability to rebuild the missing arm. This regeneration will take from several months to years, as the injury has to heal and then only regeneration of new cells take place.

Conclusion

In the given diagram, the body of the organism is flat and star like. Five arms are usually present which are not sharply marked off from the central axis. These considered the characteristics of Echinoderms.