Crustacean Anatomy

Crustaceans have compound eyes which are usually on the end of stalks. They have 2 pairs of antennae and a cuticle which is strengthened by calcium carbonate. A crustaceans head and thorax is most often covered by a carapace (shell) which extends forward to form a projection called a rostrum (a beaklike extension). Some crustaceans have additional mouthparts called maxillipeds. Unlike the internal skeletons of vertebrates, a crustaceans carapace or exoskeleton does not grow as the animal develops. Crustaceans have to molt periodically. During the molting process, every part of the body covering is shed including the covering of the eyes and fine hairs. Molting can be an exhausting ordeal and for some, things can go wrong. Some can become stuck in their old skin and the only option of escaping is to lose a claw or other appendage which unfortunately does not grow back.
A crustaceans thoracic appendages are called thoracopods and these are two branched and developed to perform various functions. These functions include feeding, moving, sensing the environment and for respiration by basal gills. The first pair of legs may be enlarged to form chelipads and are equipped with strong claws used for picking things up and defence.