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.

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.

John Cancalosi / Colorado river toad (Incilius alvarius) male calling to attract females, vocal sac filled with air. Sonoran desert, Arizona, USA. August.

John Chan / California brown pelicans (Pelecanus occidentalis californicus) stretching their gular pouches and preening, resting near to a flock of Elegant terns (Thalasseus elegans), Southern California, USA, Ma...

Lynn M. Stone / Magnificent frigate bird (Fregata magnificens) perched in Red mangrove (Rhizophora mangle) tree. Tampa Bay islet roosts, Tierra Verde, Pinellas County, Florida, USA.

Lynn M. Stone / Magnificent frigate bird (Fregata magnificens) in flight with red pouch inflated Tampa Bay, Tierra Verde, Pinellas County, Florida, USA.

Lynn M. Stone / Magnificent frigate bird (Fregata magnificens) perched in Red mangrove (Rhizophora mangle) tree. Tampa Bay islet roosts, Tierra Verde, Pinellas County, Florida, USA.

Sylvain Cordier / Humpback whale (Megaptera novaeangliae) feeding at the surface, showing expandable throat grooves, Svalbard, Norway.

Tui De Roy / Waved albatross (Phoebastria irrorata) fishhook embedded in nesting albatross' throat. Punta Suarez, Espanola Island, Galapagos.

Tui De Roy / Waved albatross (Phoebastria irrorata) with fishhook embedded in throat, Punta Suarez, Espanola Island, Galapagos.