Siphon (mollusc)
A siphon is a long tube-like structure that is present in certain aquatic molluscs: Gastropods, bivalves, and cephalopods. The tube is used for the exchange of liquids, or air. This flow can have different purposes, the most common are breathing, locomotion, feeding 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, they are paired. In cephalopods, there is a single siphon or funnel which is known as a hyponome.
Siphon (mollusc) Media
A specimen of a venerid bivalve. The adductor muscles have been cut, the valves are gaping. The internal anatomy is visible, including the paired siphons to the right
Melo amphora moving across coral at low tide
Veneridae with siphons out
Drawing of the venerid Venus verrucosa showing paired siphons (upper inhalant and lower exhalant siphon), shell and foot.
Diagramatic drawing of the inside of one valve of a bivalve such as a venerid: pallial sinus on the lower left, at the posterior end of the clam
Pomacea canaliculata, seen through glass, has reached its siphon up to the water surface to breathe air
Clam with its siphon out
Engraving of Florida freshwater applesnail Pomacea paludosa; siphon on lower right
