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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 ...
The osphradium is a pigmented chemosensory epithelium patch in the mantle cavity present in six of the eight extant classes of molluscs (it is absent in the scaphopoda and monoplacophora; among cephalopoda, only the nautilus has what appears to be a set of osphradia), on or adjacent to the ctenidia (gills).
The siphon is part of the mantle of the mollusc, and the water flow is directed to (or from) the mantle cavity. A single siphon occurs in some gastropods. In those bivalves which have siphons, the siphons are paired. In cephalopods, there is a single siphon or funnel which is known as a hyponome.
The mollusc (or mollusk [spelling 1]) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled molluscs live in the sea; many live on the land and in freshwater.
A slug on a wall in Kanagawa, Japan.. Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc.The word slug is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semi-slugs (this is in contrast to the common name snail, which applies to ...
The taxonomic term Bivalvia was first used by Linnaeus in the 10th edition of his Systema Naturae in 1758 to refer to animals having shells composed of two valves. [3] More recently, the class was known as Pelecypoda, meaning "axe-foot" (based on the shape of the foot of the animal when extended).
Some species brood the eggs within the mantle cavity, and the species Callistochiton viviparus even retains them within the ovary and gives birth to live young, an example of ovoviviparity. The egg has a tough spiny coat, and usually hatches to release a free-swimming trochophore larva, typical of many other mollusc groups. In a few cases, the ...
Scaphopoda / s k æ ˈ f ɒ p ə d ə / (plural scaphopods / ˈ s k æ f ə p ɒ d z /, from Ancient Greek σκᾰ́φης skáphē "boat" and πούς poús "foot"), whose members are also known as tusk shells or tooth shells, are a class of shelled marine invertebrates belonging to the phylum Mollusca with worldwide distribution and are the only class of exclusively infaunal marine molluscs.