Crustaceans have a hard outer body called the exoskeleton. It is made up of a substance called chitin – the same substance that your nail is made up of. Exoskeletons cannot grow, so crustaceans shed their exoskeletons in order to grow. This is called moulting. Before a crustacean moults, a new exoskeleton will start growing underneath the old one. When the animal becomes too big for the old exoskeleton, the shell cracks and the animal crawls out. The new exoskeleton will then harden to protect the animal.
|
