Chapter 27, Problem 13A

Summary Introduction

To explain: The reason for the sea stars to have a lower body temperature.

Introduction: Echinoderms are deuterostomes which represent a significant transition in animal phylogeny. Echinoderms are aquatic mammals and are the only species to have a deuterosome development and an endoskeleton in evolutionary history.

Explanation of Solution

Sea stars have grouped five arms around a central sphere. Some have over five arms. When the stars at sea are more directly exposed to sunlight. Sea stars are ectotherms and their body temperatures depend on their surrounding air. However, that does not mean their whole body is at the same temperature. The heat is not distributed equally throughout their bodies as the animals warm up.