David Shale / Fang Tooth {Anoplogaster cornuta} close-up of head showing teeth, from the Mid-Atlantic Ridge, 2600m

Nick Garbutt / Sumatran pit viper (Trimeresurus sumatranus) juvenile on tree trunk, in tropical rainforest. Danum Valley, Sabah, Borneo, Malaysia.

Fabio Pupin / Meadow viper, (Vipera ursinii), basking in alpine meadow, Apennines, Italy, September . Non-ex.

Fabio Pupin / Peringuey's desert adder, (Bitis peringueyi), sidewinding on dune, Namib desert, Namibia, February . Non-ex.

Daniel Heuclin / Sunda island pitviper (Trimeresurus insularis) in tree, Komodo Island.

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

Ingo Arndt / Prairie rattlesnake (Crotalus viridis viridis), threat display, South Dakota, USA September. Sequence 1 of 3

John Cancalosi / Male Western diamondback rattlesnake (Crotalus atrox) courting female, Sonoran Desert, Arizona, USA. Sequence 1/3.

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.