Alex Hyde / Adder (Vipera berus) basking amongst bracken fronds. Peak District National Park, Derbyshire, UK. April.

Fabio Pupin / Horned adder, (Bitis caudalis), Namib desert, Namibia, February . Non-ex.

Fabio Pupin / Horned adder, (Bitis caudalis), Namib desert, Namibia, February . Non-ex.

Emanuele Biggi / Horned adder (Bitis caudalis) portrait of a male, Brandberg, Namibia

Emanuele Biggi / Horned adder (Bitis caudalis) portrait of a male individual, Namibia

Lucas Bustamante / Horned adder (Bitis caudalis) eyes and horns, Swakopmund, Erongo, Namibia.

Lucas Bustamante / Horned adder (Bitis caudalis) curled up, Swakopmund, Erongo, Namibia.

Emanuele Biggi / Horned adder (Bitis caudalis) close up of eye, Brandberg area, Namibia

Emanuele Biggi / Horned adder (Bitis caudalis) waiting for passing prey in the Namib Desert, Brandberg, Namibia

Lucas Bustamante / Horned Adder (Bitis caudalis) eye peering from sand, Swakopmund, Erongo, Namibia.

Lucas Bustamante / Horned adder (Bitis caudalis) Swakopmund, Erongo, Namibia .

Jen Guyton / Horned adder (Bitis caudalis) camouflaged in iron-rich sand in the Kalahari Desert, South Africa.