What is the function of the arthropod exoskeleton?
a. The presence of an exoskeleton has given arthropods a good fossil record, because hard parts fossilize more readily than do soft tissues.
b. It has no well-established function. (Trilobites had an exoskeleton, and they went extinct.)
c. It provides protection and functions in locomotion.
d. It makes growth by molting possible.

Verified step by step guidance

1. Understand that the exoskeleton is a hard outer structure that covers the body of arthropods, such as insects, arachnids, and crustaceans.
2. Recognize that one of the primary functions of the exoskeleton is to provide protection to the organism. It acts as a barrier against physical damage and predators.
3. Consider the role of the exoskeleton in locomotion. The rigid structure provides points of attachment for muscles, allowing for movement.
4. Acknowledge that the exoskeleton also plays a role in growth. Arthropods must molt, or shed their exoskeleton, to grow larger, as the exoskeleton does not expand.
5. Evaluate the options given in the problem. Option c, 'It provides protection and functions in locomotion,' aligns with the known functions of the exoskeleton, while option d, 'It makes growth by molting possible,' also describes a key aspect of arthropod biology.

Key Concepts

Exoskeleton Structure

The exoskeleton is a rigid external covering that provides structural support and protection to arthropods. Composed primarily of chitin, it acts as a barrier against physical damage and desiccation. This hard outer layer is crucial for the survival of arthropods in various environments, offering a defense mechanism against predators and environmental hazards.

Protection and Locomotion

The exoskeleton serves dual functions: protection and locomotion. It shields internal organs from injury and provides attachment points for muscles, facilitating movement. This structural feature allows arthropods to perform complex movements and adapt to diverse habitats, contributing to their evolutionary success and ecological diversity.

Molting Process

Molting, or ecdysis, is the process by which arthropods shed their exoskeleton to grow. As the exoskeleton does not expand, arthropods must periodically molt to increase in size. This involves forming a new, larger exoskeleton beneath the old one, which is then shed. Molting is a critical phase in the life cycle of arthropods, allowing for growth and development.