Crustacea

Members of Subphylum Crustacea (the Crustaceans) comprise a large group of arthropods. The group contains familiar popular marine food animals such as lobsters, crabs, shrimp. While mainly found in salt and freshwater environments, there are also terrestrial Crustacea such as woodlice and isopods. Crustaceans have three distinct body parts: head, thorax, and abdomen (also called a pleon). In some, the head and thorax are fused to form a cephalothorax. They have two pairs of antennae on the head, compound eyes, three pairs of mouthparts and a telson. Crustaceans often have a thick carapace on the top (dorsal) side that makes fossilization more likely; crabs and lobsters, for example, have a thicker exoskeleton containing calcium carbonate that is more readily fossilized.