The word Mollusk comes from the Latin work meaning “soft”, and describes the bodies of organisms in the phylum Mollusca.

Mollusks, are soft-bodied invertebrates that usually have shells. They are found on land, in fresh water, and in salt water

All mollusks have a soft body usually covered by a hard shell. Covering the soft body is the mantle. The mantle is a thin layer of tissue that secrets the shell or protects the body if the mollusk does not have a shell.

After that is a space called the mantle cavity, and in it are the gills, organs that exchange oxygen and carbon dioxide with the water.

The body organs of Mollusks are located together in an area called the visceral mass.

All mollusks have a muscular foot used for movement.

Classifying a mollusk is based on whether or not the animal has a shell or not.

Mollusks that have shells are classified by the kind of shell and by the kind of foot.

There are three different classes of mollusks; Gastropods, Bivalves, and Cephalopods.

The largest class of mollusks, the gastropods, includes snails, slugs, abalones, whelks, sea slugs and conches

Organisms are usually called univalves except for slugs. Usually univalves have a pair of tentacles with eyes at the tip.

Slugs and many snails are adapted to living on land. They move by muscular contractions of the foot. Glands in the foot secret a layer of mucus for the foot to slide along in.

Slugs live where it is moist. Slugs do not have shells, but they are protected by a layer of mucus.

The second class of the three which bivalves are mollusks that have a two-part shell joined by a hinge.

Clams, oysters, and scallops are bivalves mollusks (they pull their shells closed with powerful muscles.)

When they want to open their shell they relax the muscles. The shell is made up of several layers made by the mantle. The smoothest layer is in the inside which protect the soft body.

Bivalves are well adapted to living in water. For protection a clam burrows deep in the

sand with its muscular foot. Mussels and oysters cement themselves to a

solid surface or attach themselves with a strong thread. This keeps strong waves from knocking them over.

Scallops escape predators by rapidly opening and closing their shells. As it does that it moves faster when the water is forced opposite side

The class with the most specialized and complex members are the cephalopods.

Cephalopods have a large, well-developed head. Their “foot” is divided into many tentacles with strong suckers on each for capturing prey.

Cephalopods

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