Chapter 27, Problem 15A

Summary Introduction

To write: The reason for some sea urchins to seem to have relatively long lifespans.

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

Explanation of Solution

Sea urchins burrow into rocky surroundings. In the test, the tube feet spread through pores. Sea urchins do not have arms, but their test represents the five-part pattern of arms in starfish and starfish. Any spines of sea urchins and pedicellariae carry venom and are used to fight off predators. The poison will paralyze prey in pedicellariae.

Conclusion

Thus, it concludes that sea urchins have spines used to fend off predators which will paralyze prey.