Pete Oxford / Savanna Side-necked Turtle (Podocnemis vogli) head looking above water surface, Hato Masaguaral working farm and biological station, Venezuela

Pete Oxford / Spectacled Caiman (Caiman crocodilus) in Water Lettuce (Pistia stratiotes), Hato Masaguaral working farm and biological station, Venezuela

Pete Oxford / Spectacled Caiman (Caiman crocodilus) in Water Lettuce (Pistia stratiotes), Hato Masaguaral working farm and biological station, Venezuela

Pete Oxford / Spectacled Caiman (Caiman crocodilus), Hato Masaguaral working farm and biological station, Venezuela

Pete Oxford / Spectacled Caiman (Caiman crocodilus) feeding on Capybara (Hydrochoerus hydrochaeris), Hato Masaguaral working farm and biological station, Venezuela

Pete Oxford / Savanna Side-necked Turtle (Podocnemis vogli) sunbathing, Hato Masaguaral working farm and biological station, Venezuela

Rolf Nussbaumer / American Alligator (Alligator mississippiensis) with head partially submerged, amongst Water Lettuce (Pistia stratiotes) Fennessey Ranch, Refugio, Coastal Bend, Texas Coast, USA

Martin Gabriel / Water cabbage / lettuce (Pistia stratiotes) floating on a river near Sierpe, Southern Costa Rica, February 2009

Martin Gabriel / Water cabbage / lettuce (Pistia stratiotes) floating on a river near Sierpe, Southern Costa Rica

Luciano Candisani / Water Lettuce (Pistia stratiotes) in Tapajos River, Amazon, Brazil

Ingo Arndt / Water Lettuce (Pistia stratiotes), Corkscrew Swamp Sanctuary, Florida

Adrian Davies / Water lettuce (Pistia stratiotes) with submerged roots in aquarium.