Knowra Mollusk Mollusk A soft-bodied invertebrate in the phylum Mollusca, typically built around a muscular foot, a visceral mass, and a mantle. Mollusks include snails, clams, chitons, and cephalopods.
Mantle (mollusk) : A tissue layer that covers a mollusk’s visceral mass and often secretes its shell. The mantle forms shells in many mollusks and creates the cavity that houses the gills.
Gastropoda : The largest mollusk class, including snails, slugs, limpets, and nudibranchs. Gastropods show how a mollusk can move on a broad foot, with or without an external shell.
Filter feeding : A feeding method that removes suspended particles from water or another fluid. Many bivalves draw water across their gills and capture food particles.
Pearl : A hard, lustrous structure formed within certain mollusks around an irritant or implanted nucleus. Pearls are products of shell-forming tissues in some bivalves and gastropods.
Annelid : An invertebrate in the phylum Annelida, characterized by a segmented body. Annelids and mollusks are both protostomes, but annelids have visibly segmented bodies.
Molluscan shell : A hard protective structure secreted by the mantle in many mollusks. Shells are conspicuous, but they are absent or reduced in several major mollusk lineages.
Bivalvia : A mollusk class whose members have two hinged shells, including clams, oysters, and mussels. Bivalves filter food and lack the radula found in most other mollusks.
Mollusk respiration : Gas exchange in mollusks, commonly carried out by gills or, in land snails, a lung-like mantle cavity. Mollusks use different respiratory surfaces in water and on land.
Oyster reef : A habitat formed by clusters of oysters attached to one another in coastal waters. Oysters build reefs that shelter other organisms and can reduce wave energy.
Arthropod : An invertebrate in the phylum Arthropoda, with jointed appendages and an external skeleton. Arthropods contrast with mollusks in their segmented, joint-limbed body plan.
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