02. Shellfish

Unlike fish that swim, shellfish don’t have an internal skeleton, and consequently they don’t move around much. There are two main groups: crustaceans and mollusks. Crustaceans include lobsters, crabs, crayfish, and shrimp. Mollusks are made up of single-shelled animals like abalone; double-shelled animals like mussels, clams, oysters, and scallops; and animals that have internalized their shells, namely squid and octopus.