Chapter 27, Problem 12A

Summary Introduction

To describe: Animals in terms of echinoderm classification.

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 cucumbers are the only echinoderms in the form of the respiratory trees that have respiratory organs. These multi-branched tubes flow into the anus for absorption of oxygen in seawater. In addition, the respiratory tree works in excretion by eliminating cellular waste.