Jeff Rotman / Black Blotched Porcupinefish (Diodon liturosus) inflated swimming in open ocean. Sipadan Islands, South China Sea.

Pete Oxford / Great frigatebird (Fregata minor) male displaying, pouch inflated, Galapagos

Juergen Freund / Pufferfish (Arothron) inflated Indo-Pacific

Eric Baccega / Siamang Gibbon (Hylobates syndactylus) vocalising, vocal pouch inflated, captive, native to forests of Malaysia, Sumatra and Thailand

Hans Christoph Kappel / Common tree frog calling, vocal sac inflated, Italy.

Tui De Roy / Great Frigatebird (Fregata minor) male with inflated gular pouch in courtship display, Tower Island, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) pair courting, male in full display with inflated gular air pouch, Tower Island, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) male in courtship display with fully inflated gular air pouch, Tower Island, Galapagos Islands, Ecuador

Fred Bavendam / Guineafowl Pufferfish (Arothron meleagris) in its golden color phase puffed up off of Tower Island, Galapagos Islands, Ecuador

Barry Mansell / Grey treefrog vocal sac inflated {Hyla versicolor} Florida, USA

Pete Oxford / Great frigate bird (Fregeta minor) male with pouch fully inflated. Orgenoves Island, Galapagos

Anup Shah / Siamang gibbon male calling, pouch inflated