Definitions for "Crustacea"
One of the classes of the arthropods, including lobsters and crabs; -- so called from the crustlike shell with which they are covered.
Subphylum which includes primarily aquatic arthropods with a hard exoskeleton and jointed appendages. Crustaceans are the only arthropods with two pairs of antennae. Animals in this phylum make up the most abundant part of the plankton community. Perhaps the most well known Chesapeake Bay crustacean is the Blue Crab.
class within the phylum Arthropoda noted for possessing biramus appendages and include such organisms as pill bugs, Daphnia, shrimp and crayfish