One of the two main classifications of shellfish (the other being crustacean), mollusks are invertebrates with soft bodies covered by a shell of one or more pieces. Mollusks are further divided into gastropods (also called univalves), such as the abalone and snail; bivalves, like the clam and oyster; and cephalopods, such as the octopus and squid. See also conch; cuttlefish; mussel; periwinkle; scallop; whelk.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.