| The predatory bivalves of the subclass Anomalodesmata have an incurrent siphon that can be everted rapidly to form a capacious hood beneath which small crustaceans are trapped and brought into the mantle cavity. |
| Below it is the more fleshy languette or curtain valve which closes the incurrent siphonal opening when required. |
| The siphons are completely fused with an internal septum between the incurrent siphon and the excurrent siphon. |
| Most modern bivalves are suspension feeders, and particles suspended in the water column are drawn in through the incurrent siphon by the action of the gill cillia in all but a few species. |
| Sperm is released by the male directly into the water and enters the female via the incurrent siphon. |
| Concurrent with this, the entire pectinirhomb becomes greatly protuberant along a large, thinwalled ridge spanning the incurrent and excurrent half rhombs. |
