Evolution of molluscs

The evolutionary history of molluscs, from their early origins to the diversification of major lineages and their adaptations to marine, freshwater, and terrestrial environments.

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Mollusca: A major animal phylum whose members typically have a muscular foot, visceral mass, and mantle. The phylum whose evolutionary history this page traces.
Mantle (mollusc): A fold of tissue in molluscs that covers the visceral mass and often secretes a shell. Its varied forms help compare molluscan body plans across lineages.
Cephalopod evolution: The evolutionary history of squids, octopuses, cuttlefish, and nautiluses. Cephalopods exemplify the transformation of the molluscan foot into arms and a funnel.
Aplacophora: A group of small, worm-like molluscs that lack a conventional shell and often bear calcareous spicules. These living animals offer clues to possible early molluscan body forms.
Kimberella: A late Ediacaran fossil animal often interpreted as an early bilaterian with possible molluscan affinities. Its fossils provide a debated glimpse of animal life before the Cambrian mollusc record.
Radula: A toothed feeding structure found in most molluscs, used to scrape, cut, or drill food. Its presence and modification illuminate both shared ancestry and ecological change.
Bivalve evolution: The evolutionary history of clams, oysters, mussels, and other two-shelled molluscs. Bivalves evolved a distinctive shell and feeding system suited to diverse habitats.
Monoplacophora: A class of molluscs with a single cap-shaped shell and repeated internal organs. Their anatomy has prompted comparisons with segmented ancestors and early molluscan organization.
Halkieria: A Cambrian animal with a slug-like body, two shells, and rows of sclerites. Its unusual armor has informed reconstructions of early molluscan relatives.
Molluscan foot: A muscular body region used for locomotion, attachment, or other functions in molluscs. Its transformations underpin major differences among molluscan groups.