Chapter 18, Problem 1RQ

What is a cuticle?

Summary Introduction

To explain: The cuticle.

Introduction: Ecdysozoans are a group of protostome animals that include nematodes, arthropods, and numerous smaller phyla. They have a notable characteristic in which they possess a three-layered cuticle that is molted periodically as the animal grows.

Explanation of Solution

A tough, non-cellular, outer body layer of protostomes is called the cuticle. It is a non-living external layer secreted by the epidermis of many of the protostomes such as roundworms, annelids, and arthropods. The hardened or stiffened cuticle restricts the growth of the protostomes and in such cases, as the body size increases, the cuticle is molted and the outer layer is shed through the process of ecdysis.