Gerry Ellis / Conch shell on Seven Mile Beach, Grand Turk Island, Turk and Caicos Islands, Caribbean

Juergen Freund / A colony of golden sea squirts / tunicates (Polycarpa aurata). Misool, Raja Ampat, West Papua, Indonesia, January.

Nick Upton / Wide angle view of Rayed trough shell (Mactra stultorum), partially buried in sand with siphons visible exposed on a low spring tide, with the sea in the background, Rhossili, The Gower peninsula, Wal...

Nick Upton / Wide angle view of Rayed trough shell (Mactra stultorum), partially buried in sand with siphons visible exposed on a low spring tide, with the sea in the background. Rhossili, The Gower peninsula, Wal...

Nick Upton / Rayed trough shell (Mactra stultorum), partially buried in sand with siphons visible exposed on a low spring tide. Rhossili, The Gower peninsula, Wales, UK, July.

Birgitte Wilms / Giant Clam (Tridacna sp) siphons, Solomon Islands

Juergen Freund / Golden sea squirt / tunicate (Polycarpa aurata). Misool, Raja Ampat, West Papua, Indonesia.

Robert Thompson / Zebra Mussels {Dreissena polymorpha} Lower Lough Erne, County Fermanagh, Northern Ireland, UK

Norbert Wu / Green Crenella (Musculus discors) cluster attached to dying kelp stem, siphons visible, Alaska

Norbert Wu / Green Crenella (Musculus discors) cluster attached to dying kelp stem, siphons visible, Alaska

Simon Colmer / European fingernail clam / Freshwater cockle {Sphaerium corneum} showing siphons, Sussex, UK

Pete Oxford / Mosquito (Culex sp) larvae in a Heliconia flower with breathing siphons exposed to the air, Ecuador

Pete Oxford / Mosquito (Culex sp) larvae in a Heliconia flower with breathing siphons exposed to the air, Ecuador

Pete Oxford / Mosquito (Culex sp) larvae in a Heliconia flower with breathing siphons exposed to the air, Ecuador

Alan James / Razor shell syphons {Ensis silliqua} UK