High Quality Content by WIKIPEDIA articles! Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater. In addition a few species of land crabs are eaten, for example Cardisoma guanhumi in the Caribbean.