EVERYDAY SCIENCE

Detailed explanation-1: -Gastropods is the group of molluscs that includes the snails. Many types secrete a single coiled or uncoiled shell for protection, and these shells may be found as fossils.

Detailed explanation-2: -The phylum Mollusca is the second-largest animal phylum, with over 100, 000 species. The molluscs include many familiar animals, including clams, snails, slugs, and squid, as well as some less familiar animals, like tusk shells and chitons (Fig. 3.51 A).

Detailed explanation-3: -Clams and mussels are a member of the phylum Mollusca, which also includes freshwater snails.

Detailed explanation-4: -mollusk, also spelled mollusc, any soft-bodied invertebrate of the phylum Mollusca, usually wholly or partly enclosed in a calcium carbonate shell secreted by a soft mantle covering the body.

Detailed explanation-5: -Mollusks are classified into various classes: Gastropoda, Bivalvia, Cephalopoda, and Polyplacophora (chitons). Gastropods have a spirally-coiled external shell (e.g., conch shell); others have a flattened shell, while some do not possess a shell.