Which mollusk class includes clams, mussels, and oysters?

Which mollusk class includes clams, mussels, and oysters?

• A. Gastropoda
• B. Polyplacophora
• C. Bivalvia
• D. Cephalopoda

Answer: (C)

Two-shelled, filter-feeding mollusks define this group. Clams, mussels, and oysters have a pair of hinged shells (valves) that enclose a laterally compressed body, and they usually lack a distinct head with a radula. They feed by filtering water through their gills, which trap food particles as they pass by. This combination of a two-valved shell and a sedentary, filter-feeding lifestyle identifies the class that includes these animals. In contrast, gastropods usually have a single shell or none and a distinct head, polyplacophorans have eight plates, and cephalopods feature a prominent head with tentacles and a highly developed nervous system.

Two-shelled, filter-feeding mollusks define this group. Clams, mussels, and oysters have a pair of hinged shells (valves) that enclose a laterally compressed body, and they usually lack a distinct head with a radula. They feed by filtering water through their gills, which trap food particles as they pass by. This combination of a two-valved shell and a sedentary, filter-feeding lifestyle identifies the class that includes these animals. In contrast, gastropods usually have a single shell or none and a distinct head, polyplacophorans have eight plates, and cephalopods feature a prominent head with tentacles and a highly developed nervous system.