Doug Allan / Emperor penguin males incubating eggs huddle for warmth at -40 degrees centigrade, winter, Antarctica. Green is excrement on snow. {Aptenodytes forsteri}

Doug Allan / Emperor penguin {Aptenodytes forsteri} males huddle for warmth in minus 40 degrees centigrade while incubating eggs in winter, Antarctica Winter extreme cold survival birds seabirds nesting-behaviour

Claudio Contreras / American crocodile (Crocodylus acutus) extreme close up with jaws open, Banco Chinchorro Biosphere Reserve, Caribbean region, Mexico

Christophe Courteau / Lava Lake at night in the crater of Nyiragongo Volcano, Virunga National Park, North Kivu Province, Democratic Republic of Congo. September 2015.

Christophe Courteau / Lava Lake at night in the crater of Nyiragongo Volcano, Virunga National Park, North Kivu Province, Democratic Republic of Congo. September 2015.

Luis Quinta / Storm waves off the coast of Praia do Norte, Nazare, Portugal. January.

Franco Banfi / Great white shark (Carcharodon carcharias) swimming in front of scuba diving cages, Guadalupe Island, Mexico, Pacific Ocean. September 2011.

Sven Zacek / Broken ice covered in snow at sunset, on the shore of Lake Vortsjarv, gathered to shore by extreme winds, Estonia. December 2014.

Espen Bergersen / Atlantic puffin (Fratercula arctica) two fighting in snow, Hornoya bird cliff, Finnmark, Norway. March.

Espen Bergersen / Atlantic puffin (Fratercula arctica) two birds fighting at nesting ground, Hornoya bird cliff, Finnmark, Norway. March.

Espen Bergersen / Atlantic puffin (Fratercula arctica) two calling aggresively in snow, Hornya birdcliff, Finnmark, Norway.

Alex Hyde / Close-up of Owl Butterfly (Caligo memnon) head showing compound eyes and proboscis. Captive, originating from Central America.