mollusk

animal phylum
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Also known as: Mollusca, mollusc
organizational levels and body diagrams of mollusks
organizational levels and body diagrams of mollusks
Key People:
William Keith Brooks Augustus A. Gould
Related Topics:
gastropod bivalve cephalopod chiton nephridium

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. Along with the insects and vertebrates, it is one of the most diverse groups in the animal kingdom, with nearly 100,000 (possibly as many as 150,000) described species. Each group includes an ecologically and structurally immense variety of forms: the shell-less Caudofoveata; the narrow-footed gliders (Solenogastres); the serially valved chitons (Placophora or Polyplacophora); the cap-shaped neopilinids (Monoplacophora); the limpets, snails, and slugs (Gastropoda); the clams, mussels, scallops, oysters, shipworms, and cockles ...(100 of 5138 words)