What are the typical traits of crustaceans?

Answer 1

All crustaceans have:

• Two pairs of antennae at some stage in their life cycle.
• The body is divided into three parts, a head, thorax and abdomen.
• There may be between sixteen and sixty body segments. Although the segments look like rings, the outer shell is continuous. The hard tube-like parts are hardened by deposits of calcium and protein. At the joints the shell is thin and flexible, so that the body may bend.
• The Head carries pairs of appendages, usually the antennae, used for sensing its environment and for feeding. The head also carries three pair of appendages that are modified into mouthparts.
• Most crustaceans have a carapace, or shell, which folds outwards from the upper surface of the body and covers all or part of the thorax.
• The thorax and abdomen have pairs of appendages used for movement such as walking, swimming, climbing. In some cases these appendages are used for respiration and mating.
• In advanced crustaceans, such as the prawns, lobsters and crabs, three pair of thoracic appendages help the head mouthparts to handle food.