SHRIMPShrimp: any of about 2000 species of crustacean of the order which includes crabs,crayfish, and lobsters. Shrimp range in size from that of small insects to lengths of morethan 20 cm (more than 8 in). The term prawn is applied to larger species. Shrimp inhabit salt water and fresh water and are mostly found on shallow seafloors, where they feed on small animals and plants. Some species are pelagic, swimming in open oceans, sometimes at a depth of nearly 5 km (nearly 3 mi). Shrimp are structurally similar to lobsters and crayfish, but they lack enlarged pincers and are flattened laterally instead of horizontally. The animals are usually transparent or are green or brown in color. They have thick-muscled abdomens, which they contract rapidly in making their sudden, backward-swimming escapes. (The shrimp meat served in numerous dishes, an important product of the fishing industry, is the curved muscle extracted from the abdomen.) The animals have eight pairs of appendages on the thorax: the front three, called maxillipeds, are mouthparts used for feeding; the rear five, called pereipods, are used for walking. The abdomen contains five pairs of swimming legs, called pleopods, and a fanlike tail.
The most common commercial shrimp in waters near the United States is the white shrimp. Two other important species are the pink-grooved shrimp and the popular prawn of the Pacific Northwest coast. Scientific classification: Shrimp belong to the order Decapoda. The white shrimp is classified as Penaeus setiferus, the pink-grooved shrimp as Penaeus duorarum, and the Pacific Northwest prawn as Crangon franciscorum.