Steven Kazlowski / Polar bear (Ursus maritimus) female walking on a barrier island at sunset with a full moon rising, Bernard Spit, Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) large adult walking along a barrier island, Bernard Spit, waiting for autumn freeze up so it can head out onto the sea ice to hunt, Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) female playing with her cub along a barrier island on the Arctic coast, off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bears {Ursus maritimus} group of adult males rest on a barrier island waiting for ocean freeze up, off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) female nurses her cubs on a barrier island, off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) female with cub waits on a barrier island for ocean freeze up, full moon, off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus), collared adult female, on a barrier island off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) in the water along a barrier island off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) adult female standing to get a better look at what is approaching, along a barrier island on the Arctic coast, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) female with cubs wait on a barrier island for ocean freeze up, off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) walking along a barrier island off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) cub mistakenly bites its mothers mouth, along a barrier island on the Arctic coast, Alaska

Steven Kazlowski / Polar bears {Ursus maritimus} group of adult males wait on a barrier island for ocean freeze up, off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus), collared adult female, on a barrier island off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bears {Ursus maritimus} group of adult males wait on a barrier island for ocean freeze up, off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bears (Ursus maritimus), some collared, along a barrier island on the Arctic coast, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus), female, along a barrier island on the Arctic coast, Alaska

Steven Kazlowski / Polar bear (Ursus maritimus) pair of adult males on a barrier island waiting for ocean freeze up, off the Arctic National Wildlife Refuge, Alaska

Steven Kazlowski / Polar bears {Ursus maritimus} pair of adult males rest on a barrier island waiting for ocean freeze up, off the Arctic National Wildlife Refuge, Alaska

Ross and Diane Armstrong / North Island Kaka (Nestor meridionalis septentrionalis) portrait, Little Barrier Island, New Zealand

NEIL NIGHTINGALE / Sir David Attenborough in scuba diving equipment on location for BBC television series "Private Life of Plants", early 1990s. Heron Island, Great Barrier Reef, Australia

Juergen Freund / Aerial view of Green Island, on the Great Barrier Reef, Queensland, Australia

Juergen Freund / Aerial view of a Sand Cay on the Great Barrier Reef, Queensland, Australia

Juergen Freund / Aerial view of Green Island, on the Great Barrier Reef, Queensland, Australia

Steven David Miller / Land hermit crab {Isocheles pilosus}, Lady Elliott Island, Great Barrier Reef, Queensland, Australia

Steven David Miller / Wreck forms breakwater at harbour. Heron Island, Great Barrier Reef, QLD, Australia

Steven David Miller / Hard coral (Acropora sp) Lady Elliott Island, Great Barrier Reef, Queensland, Australia

Steven David Miller / Aerial view of Lady Elliot Island, Great Barrier Reef, Queensland, Australia

Fred Bavendam / Crescent-tail Bigeye (Priacanthus hamrur) school, underwater, side view, Lizard Island, Great Barrier Reef, Queensland, Australia

Brent Hedges / Head profile of Starry puffer {Arothron stellatus}, Heron Island, Great Barrier Reef, Australia

Martha Holmes / Female Green turtle laying eggs at night (Chelonia mydas) Raine Island, Great Barrier Reef, Australia

Doug Wechsler / Aerial view of urban expansion - extensive development of coastal wetlands, Sea Isle City, Barrier Island, New Jersey, USA

Steven David Miller / White capped noddy {Anous minutus} perched on tree at beach, Heron Island, Great Barrier Reef, Queensland, Australia

Steven David Miller / Sacred kingfisher adult male (Todiramphus sancta) Australia Heron Island, Gt Barrier Reef

Steven David Miller / Carl Johnson-Lovers Key State Park showing Barrier Island and mangroves, Florida, USA.

Phil Savoie / Cruise ship in Caribbean off Barrier Reef, Belize.

Tom Vezo / Peregrine Falcon (Falco peregrinus) flying, Fire Island Barrier Beach, Long Island, New York

Tom Vezo / Peregrine Falcon (Falco peregrinus) flying, Fire Island Barrier Beach, Long Island, New York

Gerry Ellis / Aerial view of Whitsunday Island, Great Barrier Reef Marine Park, Queensland, Australia

Gerry Ellis / Aerial view of Heron Island, Great Barrier Reef Marine Park, Queensland, Australia

Norbert Wu / Coral cay on Great Barrier Reef, Australia

Flip Nicklin / Dwarf Minke Whale (Balaenoptera acutorostrata) near Lizard Island and the Great Barrier Reef, Australia

Mitsuaki Iwago / Catchbirdtree (Pisonia sp) forest on Wilson Island, Great Barrier Reef, Queensland, Australia

Norbert Wu / Lizard Island, Great Barrier Reef, Australia

Fred Bavendam / Feather Star (Oxycomanthus bennetti) clinging to a Harp Gorgonian (Ctenocella pectinata), Lizard Island, Great Barrier Reef, Queensland, Australia

Flip Nicklin / Dwarf Minke Whale (Balaenoptera acutorostrata) surfacing, Lizard Island near the Great Barrier Reef, Australia

Fred Bavendam / Blackfin Barracuda (Sphyraena qenie) schooling, Lizard Island, Great Barrier Reef, Queensland, Australia

Dave Watts / Aerial view of Lady Elliot Island, Great Barrier Reef, Queensland, Australia

Steven David Miller / Coral Cay aerial shot, Capricorn bunker group. Great Barrier Reef, Queensland Australia

Steven David Miller / Blue and gold fusilier school (Caesio teres) Great Barrier Reef, Heron Is, Australia.

Dave Watts / Red tailed tropic bird in flight {Phaethon rubricauda} Lady Eliot Island, Australia, Great Barrier Reef

Steven David Miller / Hermit crab hunting on beach at night. Great Barrier Reef Lady Elliot Island, Australia

Steven David Miller / Hermit crab living in tritan shell, underwater at night, Great Barrier Reef, Lady Elliot Island, Australia

Steven David Miller / Green turtle female returning to sea {Chelonia mydas} after laying eggs, Great Barrier Reef, Heron island, Australia

Roberto Rinaldi / Aerial view of Heron Island, Great Barrier Reef, Australia

Roberto Rinaldi / Aerial view of Heron Island, Great Barrier Reef, Australia

Roberto Rinaldi / Diving lesson in Heron Island swimming pool, Great Barrier Reef, Australia

Roberto Rinaldi / Shoal of snappers (Lutjanidae sp.), Heron Island, Great Barrier Reef, Australia

Roberto Rinaldi / Diver swimming over a brain coral at Heron Island, Great Barrier Reef, Australia

Roberto Rinaldi / Aerial view of Heron Island, Great Barrier Reef, Australia

Roberto Rinaldi / Aerial view of Heron Island with visible coral reef, Great Barrier Reef, Australia

Roberto Rinaldi / Aerial view of Heron Island, Great Barrier Reef, Australia

Roberto Rinaldi / Shoal of snappers (Lutjanidae sp.), Heron Island, Great Barrier Reef, Australia

Roberto Rinaldi / Aerial view of Heron Island, Great Barrier Reef, Australia

Norbert Wu / Reef-walking, Great Barrier Reef, Heron Island, Australia

Flip Nicklin / Dwarf Minke Whale (Balaenoptera acutorostrata) near Lizard Island and the Great Barrier Reef, Australia

Norbert Wu / Motu or reef island, formed of accumulated sand and debris on the Belize Barrier Reef

Flip Nicklin / Dwarf Minke Whale (Balaenoptera acutorostrata) breaching, Lizard Island near the Great Barrier Reef, Australia

Flip Nicklin / Dwarf Minke Whale (Balaenoptera acutorostrata) surfacing, Lizard Island near the Great Barrier Reef, Australia

Steven David Miller / Aerial view of Heron Island Great Barrier Reef Queensland Australia Capricorn-Bunker

Phil Savoie / Smithsonian marine research station, Carrie Bow Caye, Barrier Reef, Belize

Tim Edwards / Female Kakapo {Strigops habroptilus} fed apple prior to release. Little Barrier Is New