Crabs are a type of crustacean that belong to the same family as lobsters, shrimp, and crayfish. They are found in oceans, freshwater, and on land. They have a hard exoskeleton, two claws, and eight legs, with the front pair often used for grabbing and defending themselves. Crabs come in various sizes, shapes, and colors, and are an important part of marine ecosystems, as well as a popular seafood delicacy.