Mark Brownlow / Sperm whale {Physeter macrocephalus} diving, tail fluke, Kaikoura, South Island, New Zealand

Neil Anderson / Red squirrel (Sciurus vulgaris), two curled up asleep in drey inside nest box. Nest of lichen and Pine needles. Highlands, Scotland, UK. Medium repro only.

Bernard Castelein / Silky sifaka (Propithecus candidus) in tree, Marojejy National Park, Madagascar. Critically endagered species.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) group clambering up slope during journey to bring back food for young. Atka Bay, Antarctica. September.

Silke Arndt / Western rattlesnake (Crotalus viridis viridis), threat display, South Dakota, USA, September.

Ingo Arndt / Madagascar moon moth (Argema mitrei), Captive

Espen Bergersen / Sperm whale (Physeter macrocephalus) tail fluke visible as whale dives. outside Andoya, Norway March

Claudio Contreras / American crocodile (Crocodylus acutus) rear view of animal swimming away over seagrass bed, Banco Chinchorro Biosphere Reserve, Caribbean region, Mexico

Claudio Contreras / American crocodile (Crocodylus acutus) rear view of animal resting in shallow water, close up of tail, Banco Chinchorro Biosphere Reserve, Caribbean region, Mexico

Tony Wu / Humpback whale (Megaptera novaeangliae) executing a dramatic tail slap, throwing up a cascade of water with its powerful fluke, Vava'u, Tonga, South Pacific

Tony Wu / Humpback whales (Megaptera novaeangliae) unusual scene with two adults tail-slapping together in rough seas, Vava'u, Tonga, South Pacific

Bence Mate / Western diamond-backed rattlesnake (Crotalus atrox) Texas, USA, April.