What is the difference between crustaceans and shellfish?
Crustaceans are aquatic animals that have jointed legs, a hard shell and no backbone, such as crab, crayfish, lobster, prawns and shrimp. Shellfish (also known as molluscs) have a hinged two-part shell and include clams, mussels, oysters and scallops, and various types of octopus, snails and squid.