Doug Perrine / Bryde's whale {Balaenoptera brydei / edeni} with throat pleats expanded after feeding on baitball of Sardines {Sardinops sagax} off Baja California, Mexico, Eastern Pacific Ocean. Veolia Environnement...

Tony Wu / View down the throat of a male Zoarchias major eelpout (Zoarchias major) that has opened its mouth during a confrontation with another male. Yamaguchi Prefecture, Japan. Pacific Ocean.

Mark Carwardine / Aerial view of Fin whale (Balaenoptera physalus) lunge-feeding, with throat pouch distended, southern Sea of Cortez (Gulf of California), Baja California, Mexico.

Mark Carwardine / Aerial view of Fin whale (Balaenoptera physalus) lunge-feeding, with mouth open and throat pouch distended, southern Sea of Cortez (Gulf of California), Baja California, Mexico.

Tui De Roy / Short tailed albatross (Phoebastria albatrus) subadult with fish-hook and monofilament line embedded in throat. Tsubamezaki, Torishima Island, Japan. December.

Tui De Roy / Short tailed albatross (Phoebastria albatrus) subadults courting, one with fish-hook and monofilament line embedded in throat. Tsubamezaki, Torishima Island, Japan. December.

Tui De Roy / Waved albatross (Phoebastria irrorata) on nest, with fish hook in throat, Punta Suarez, Espanola Island, Galapagos.

Konrad Wothe / Three-striped poison frog (Ameerega trivittata) croaking, Panguana Reserve, Huanuco Region, Peru.

Brent Stephenson / Humpback whale (Megaptera novaeangliae) surfacing whilst lunge-feeding, showing the extended throat pleats, Neko Harbour, Antarctic Peninsula, Antarctica, January.

Ole Jorgen Liodden / Magnificent frigatebird (Fregata magnificens) male with gular pouch, Galapagos.

Ole Jorgen Liodden / Brown pelican (Pelecanus occidentalis urinator) close up of throat pouch skin, with beak open, Galapagos.

Doc White / Blue Whales (Balaenoptera musculus) throat inflated, filter feeding at sea surface. California, USA. Sequence 1 of 2.