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

Daniel Heuclin / Western diamondback rattlesnake (Crotalus atrox) tasting air, in habitat, Arizona, USA, October. Controlled conditions

Juergen Freund / Banded sea kraits (Laticauda colubrina) around the roots of mangrove tree, split level. Mali Island, Macuata Province, Fiji, South Pacific.

Chris Mattison / Sidewinder (Crotalus cerstastes) in sand dunes, Anza-Borrego Desert State Park, California, USA, May.

Daniel Heuclin / Mojave rattlesnake (Crotalus scutulatus) Mojave desert, California, June.

Daniel Heuclin / Rhinoceros viper (Bitis nasicornis), from Central Africa, captive, July.

Daniel Heuclin / Usambara bush Viper (Atheris ceratophora) captive from Tanzania, vulnerable species

Daniel Heuclin / Sand Viper (Cerastes vipera) side winding across sand dunes, near Chingueti, Mauritania

Daniel Heuclin / Sand Viper (Cerastes vipera) in shade of grass, Erg Chigaga, Morocco

Bert Willaert / Juvenile male Caucasus viper (Daboia raddei / Vipera kaznakovi), Georgia, September.

Michael D. Kern / Sri Lankan Bamboo Pitviper (Trimeresurus trigonocephalus) captive, from Sri Lanka

Michael D. Kern / Bamboo pitviper, (Viridovipera stejnegeri) captive from Asia