Chapter 31, Problem 7STP

Summary Introduction

Introduction:

Echinoderms are a major group of marine animals. There are about 7,000 species found usually on the sea floor in every marine habitat. There is a wide variety of colours and the body is uniquely shaped.

Answer to Problem 7STP

The correct answer is Option (b) Respiration.

Explanation of Solution

Explanation/justification for the correct answer:

Option (b) Respiration. As Echinoderms have a poorly designed respiratory system, they make use of their gills and their tube feet to take in oxygen and pass out carbon dioxide. Respiration occurs in two locations on starfish- dermal gills and papulae.

Explanation for incorrect answer:

Option (a) Reproduction- Echinoderms are sexually dimorphic and release their eggs and sperm cells into water, their fertilization is external. So, the correct answer is Option (b)

Option (c) Sensing gravity. Echinoderms use tube feet for locomotion and respiration, so the correct answer is Option (b)

Option (d) Sensing light -Echinoderms use tube feet for locomotion and respiration, so the correct answer is Option (b)

Conclusion

Echinoderms use tube feet for locomotion and respiration, so the correct answer is Option (b).