Siphon (molluscs)

A siphon is an anatomical structure which is part of the body of aquatic molluscs in three classes: Gastropoda, Bivalvia and Cephalopoda (members of these classes include saltwater and freshwater snails, clams, octopus, squid and relatives).

Siphons in molluscs are tube-like structures in which water flows (or more rarely in which air flows). The water flow is used for one or more purposes such as locomotion, feeding, respiration, and reproduction. 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.

In some (but not all) sea snails, marine gastropod molluscs, the animal has an anterior extension of the mantle called a siphon, or inhalant siphon, through which water is drawn into the mantle cavity and over the gill for respiration.

This siphon is a soft fleshy tube-like structure equipped with chemoreceptors which "smell" or "taste" the water, in order to hunt for food. Marine gastropods that have a siphon are either predators or scavengers.

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