Molluscs

Molluscs are a large phylum of soft-bodied invertebrate animals, usually protected by a calcium carbonate shell.

Molluscs are a large phylum of soft-bodied invertebrate animals, usually protected by a calcium carbonate shell. They include familiar groups such as snails, clams, mussels, octopuses, and squid, and live in marine, freshwater, and terrestrial habitats. Molluscs are among the most diverse animal groups, with about 100,000 living described species in some references and higher estimates in others.

Classification

Molluscs form one of the major animal phyla, Mollusca. Living molluscs are commonly grouped into classes such as gastropods, bivalves, cephalopods, chitons, scaphopods, aplacophorans, and monoplacophorans.

Anatomy and traits

Most molluscs have a soft body, a mantle that often secretes a calcium carbonate shell, and a muscular foot. Many also have a radula for feeding, although this structure is absent in bivalves.

Habitats and diversity

Molluscs inhabit marine, freshwater, and terrestrial environments. They are among the most diverse animal groups, with living species counts commonly given at around 100,000, though some sources give higher estimates.

Examples and significance

Well-known molluscs include snails, slugs, clams, mussels, oysters, squid, and octopuses. They are important in ecosystems and have long been significant to people as food, shell material, and fossil specimens.