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The mantle cavity is a central feature of molluscan biology. This cavity is formed by the mantle skirt, a double fold of mantle which encloses a water space. This space contains the mollusk's gills, anus, osphradium, nephridiopores, and gonopores. The mantle cavity functions as a respiratory chamber in most mollusks. In bivalves it is usually ...
Terrestrial molluscs or land molluscs (mollusks) are an ecological group that includes all molluscs that live on land in contrast to freshwater and marine molluscs. They probably first occurred in the Carboniferous , arising from freshwater ones .
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where the head-foot part of the body of the animal emerges for locomotion, feeding, etc. The term aperture is used for the main opening in gastropod shells, scaphopod shells, and also for Nautilus and ammonite shells.
The most frequently used measurements of a gastropod shell are: the height of the shell, the width of the shell, the height of the aperture and the width of the aperture. The number of whorls is also often used. In this context, the height (or the length) of a shell is its maximum measurement along the central axis.
The mantle is a multifunctional, generally thin and fragile structure that line bivalve interiors and encloses their bodies. This structure secretes the shell, contains respiratory organs and facilitates feeding. The cavity that exists between the mantle and other soft tissues is aptly named the mantle cavity. [4]
The bivalve's two siphons are situated at the posterior edge of the mantle cavity. [11] There is an inhalant or incurrent siphon, and an exhalant or excurrent siphon. [12] The water is circulated by the action of the gills. Usually water enters the mantle cavity through the inhalant siphon, moves over the gills, and leaves through the exhalant ...
Arca noae is found in the Mediterranean Sea. It was once common in the Adriatic, but in 1949/50 there was a sudden unexplained, catastrophic decline in numbers. Since then, populations have been creeping back upwards, and in 2002, densities of up to 13 individuals per square metre (11 square feet) were recorded.
The ctenidium hangs into the mantle cavity and increases the area available for gas exchange. [7] The word is Latinized but is derived from the Greek ktenidion which means "little comb", being a diminutive of the word kteis meaning comb.