Ingo Arndt / Mastigias jellyfish (Mastigias sp) with mass of jellyfish in background, Jellyfish lake, Palau, Western Pacific Islands, Micronesia

Ingo Arndt / Mass of Mastigias jellyfish (Mastigias sp) in Jellyfish lake, Palau, Western Pacific Islands, Micronesia, March 2009

Alex Mustard / Two Florida manatee (Trichechus manatus latirostrus) surfacing to breathe, in morning light. Three Sisters Spring, Crystal River, Florida. USA. January

Alex Mustard / Bluegill sunfish (Lepomis macrochirus) sheltering beneath a Florida manatee (Trichechus manatus latirostrus). Crystal River, Florida, USA.

Alex Mustard / Young Florida manatee (Trichechus manatus latirostrus) stays warm in a freshwater spring in winter, at dawn. Three Sisters Spring, Crystal River, Florida, USA. January

Alex Mustard / Florida manatee (Trichechus manatus latirostrus) swimming under trees in Three Sisters Spring, Crystal River, Florida, USA. January

Jack Dykinga / Red Mangroves (Rhizophora mangle) lining the brackish water of the La Tovara Wetlands, San Blas, Mexico, Central America

Michael Pitts / Jellyfish {Mastigias sp} in Jellyfish lake Palau Micronesi

Juergen Freund / Stingless jellyfish float in brackish water lake, Kalaban Is, Kalimantan, Indonesia

Eladio Fernandez / American flamingo (Phoenicopterus ruber) taking off in a brackish lagoon, Jaragua National Park, Dominican Republic.

Robert Thompson / Common hawker (Aeshna juncea) Brackish Moss NNR, County Armagh, Northern Ireland.

Ingo Arndt / Diver working underwater amongst mass of Mastigias jellyfish (Mastigias sp) in Jellyfish lake, Palau, Western Pacific Islands, Micronesia, March 2009