* Protection: The hard shell acts as a protective armor, shielding the crab from predators and environmental hazards. It protects its soft body from being crushed, bitten, or injured.
* Support: The exoskeleton provides structural support, allowing the crab to move and maintain its shape. It acts like a rigid framework, holding the crab together.
* Muscle Attachment: Muscles attach to the inside of the shell, providing the leverage needed for the crab to move its legs and claws.
* Water Retention: The hard shell helps the crab retain moisture in its body, which is important for survival in a terrestrial environment.
Important to note: While the hard shell is beneficial, it also presents challenges for the crab. Since it doesn't grow with the crab, it must periodically shed its shell (molting) and grow a new, larger one. This process leaves the crab vulnerable until the new shell hardens.