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Shell of marine snail Lunella torquata with the calcareous operculum in place Gastropod shell of the freshwater snail Viviparus contectus with corneous operculum in place. An operculum (Latin for 'cover, covering'; pl. opercula or operculums) is a corneous or calcareous anatomical structure like a trapdoor that exists in many (but not all) groups of sea snails and freshwater snails, and also ...
An operculum is a somewhat similar but permanent anatomical feature that is found in other clades of gastropods. The operculum serves some of the same functions as an epiphragm. Sometimes it protects the snail against predation. It protects certain species of snail if they are eaten by birds (such as Japanese white-eye). The snail can remain ...
Notched – Nicked or indented, as the anterior canal of some gastropods. [1] Nucleus – The first part or beginning, as the apex in a gastropod shell. [1] Nucleated – Having a nucleus. [1] Obconic – In the form of a reversed cone. [1] Oblique – Slanting, as the aperture of some shells when not parallel to the longitudinal axis. [1]
The word gastropod comes from Greek γαστήρ (gastḗr 'stomach') and πούς (poús 'foot'), a reference to the fact that the animal's "foot" is positioned below its guts. [7] The earlier name "univalve" means one valve (or shell), in contrast to bivalves, such as clams, which have two valves or shells.
Calliostoma is a genus of small to medium-sized sea snails with gills and an operculum, marine gastropod molluscs within the family Calliostomatidae, the Calliostoma top snails. Previously this genus was placed within the family Trochidae. Calliostoma is the type genus of the family Calliostomatidae.
Operculum (animal), a structure resembling a lid or a small door that opens and closes; Operculum (bird), a structure which covers the nares of some birds; Operculum (bryozoa), a lid on the orifice of some bryozoans; Operculum (fish), a flap covering the gills of bony fish; Operculum (gastropod), a sort of trapdoor used to close the aperture of ...
According to an estimate from Cameron, [4] of the 409 existing gastropod families, 119 include terrestrial molluscs. Among these 119 families, 104 are Stylommatophora, 7 are terrestrial pulmonates other than stylommatophorans, and 8 are operculates (formerly "prosobranchs", molluscs with an operculum, a group that primarily consists of marine ...
An operculum (gastropod), a single lid that (in its most complete form) closes the aperture of the shell when the animal is retracted, and thus protects the internal soft parts of the animal that are not completely covered by the shell. The operculum lies on the top rear part of the foot.