Crustacea

Examples of Crustaceans:

• crabs
• lobsters
• crayfish
• shrimp
• barnacles*

General characteristics:

• live in marine and freshwater environments (for the most part)
• 2 pairs of antennae
• 3 or 4 appendages modified as mouthparts, including hard mandibles
• walking legs on the thorax and abdomen
• lost appendages can be regenerated
• small crustaceans exchanges gases through thin areas of the cuticle (their exoskeleton), while larger species have gills.

Groups of crustaceans:

• isopoda
• copepoda
• decapoda

Crus*ta"ce*a (kr?s-t?"sh?-?), n. pl. [Neut. pl. of NL. crustaceus pert. to the crust or shell, from L. crusta the hard surfsce of a body, rind, shell.] Zool.

One of the classes of the arthropods, including lobsters and crabs; -- so called from the crustlike shell with which they are covered.

⇒ The body usually consists of an anterior part, made up of the head and thorax combined, called the cephalothorax, and of a posterior jointed part called the abdomen, postabdomen, and (improperly) tail. They breathe by means of gills variously attached to some of the limbs or to the sides the body, according to the group. They are divisible into two subclasses, Entomostraca and Malacostraca, each of which includes several orders.

© Webster 1913.