Picture your last seafood meal, and
you're probably seeing a crustacean. Crustaceans are mostly water-dwelling
invertebrates (no spine), characterized by a jointed body and limbs,
and a hard outer shell called an exoskeleton. Although some species
live on land, the most common and identifiable crustaceans are ocean-dwellers,
such as lobsters, crabs, and even shrimp and barnacles.