Michael D. Kern / Hairy bush viper (Atheris hispida) captive, from Central Africa

Michael D. Kern / Usambara bush viper (Atheris ceratophora) captive, from Tanzania, vulnerable species

Michael D. Kern / Usambara Bush Viper (Atheris ceratophora) coiled, ready to strike, captive, from Tanzania, vulnerable species

Michael D. Kern / African / Variable Bush Viper (Atheris squamigera) captive, from West and Central Africa

Michael D. Kern / Broadley's Bush Viper (Atheris broadleyi) captive from Cameroon and Central African Republic

Michael D. Kern / Broadley's Bush Viper (Atheris broadleyi) captive from Cameroon and Central African Republic

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

Michael D. Kern / Field's Horned Viper, (Pseudocerastes persicus fieldi) captive, from Middle East

Michael D. Kern / Field's Horned Viper, (Pseudocerastes persicus fieldi) captive, from Middle East

Michael D. Kern / Field's Horned Viper, (Pseudocerastes persicus fieldi) captive, from Middle East

Michael D. Kern / Eyelash Viper (Bothriechis schlegelii), captive, from Central and South America

Michael D. Kern / Side-Striped Palm Viper (Bothriechis lateralis) captive from Central America

Michael D. Kern / African / variable Bush Viper (Atheris squamigera) captive from West and Central Africa

Michael D. Kern / Hairy Bush Viper (Atheris hispida), captive from Central Africa

Michael D. Kern / Javanese / Flat-nosed pitviper (Trimeresurus puniceus) captive, from Indonesia

Daniel Heuclin / Gaboon Viper (Bitis gabonica rhinoceros) handled by worker at venom collection laboratory. Ghana, Africa.

Daniel Heuclin / Gaboon Viper (Bitis gabonica rhinoceros) handled by worker at venom collection laboratory. Ghana, Africa.

Daniel Heuclin / Gaboon Viper (Bitis gabonica rhinoceros) handled by worker at venom collection laboratory, showing large fangs. Ghana, Africa.

Daniel Heuclin / Extracting venom from Gaboon Viper (Bitis gabonica rhinoceros) for the production of antivenom. Ghana, Africa.

Daniel Heuclin / Kramer's / Large Eyed Pit Viper (Cryptelytrops / Trimeresurus macrops). Captive. Endemic to South East Asia.

Shibai Xiao / An old man sitting in front of his house with arm deformed by Hundred-pace pitviper snake bite (Deinagkistrodon acutus) Fanjingshan National Nature Reserve, Guizhou Province, China, June 2008.

Shibai Xiao / Bamboo / Stejnegeri viper (Trimeresurus stejnegeri) moving along branch in tree, Bawangling National Nature Reserve, Hainan Island, China.

Shibai Xiao / Bamboo / Stejnegeri viper (Trimeresurus stejnegeri) head peering out from leaves, Bawangling National Nature Reserve, Hainan Island, China.

Shibai Xiao / Hundred pace pitviper (Deinagkistrodon acutus) on rock, Guizhou Province, China. Captive.

Shibai Xiao / Hundred pace pitviper (Deinagkistrodon acutus) lurking along stoney path, Guizhou Province, China.

Shibai Xiao / White lipped palm / tree viper (Trimeresurus albolabris) in tree with a defensive posture, Fanjingshan National Nature Reserve, Guizhou Province, China.

Daniel Heuclin / Desert horned viper (Cerastes cerastes) with mouth wide about to strike, Captive, from Morocco

Daniel Heuclin / Desert horned viper (Cerastes cerastes) with mouth wide about to strike, Captive, from Morocco

Daniel Heuclin / Desert horned viper (Cerastes cerastes) with mouth wide about to strike, Captive, from Morocco

Daniel Heuclin / Desert horned viper (Cerastes cerastes) about to strike, Captive, from Morocco

Daniel Heuclin / Desert horned viper (Cerastes cerastes) about to strike, Captive, from Morocco

Adrian Davies / Flowers on beach, including Red valerian (Centranthus ruber) Viper's bugloss (Echium vulgare) Sea mayweed (Matricaria maritima) Sea spurge (Euphorbia paralias) Sea carrot (Daucus carota) Slapton, Devo...

Adrian Davies / Flowers on beach, including Red valerian (Centranthus ruber) Viper's bugloss (Echium vulgare) Sea mayweed (Matricaria maritima) Sea spurge (Euphorbia paralias) Sea carrot (Daucus carota) Slapton, Devo...

Daniel Heuclin / Wagner's viper (Montivipera / Vipera wagneri) captive, from Eastern Turkey, Iran. Critically endangered

Daniel Heuclin / Wagner's viper (Montivipera / Vipera wagneri) captive, from Eastern Turkey, Iran. Critically endangered

Daniel Heuclin / Moorish viper (Daboia / Macrovipera mauritanica) captive, from Morocco

Daniel Heuclin / Asp Viper (Vipera aspis) captive

Daniel Heuclin / Sri Lankan Pit Viper (Trimeresurus trigonocephalus) captive

Daniel Heuclin / Pope's pitviper (Trimeresurus / Popeia popeorum)captive, from SE Asia

Daniel Heuclin / Hagen's pit viper (Trimeresurus / Parias hageni) captive, from SE Asia

Daniel Heuclin / Milos viper (Macrovipera schweizeri) Cyclades islands, Greece, captive

Sandesh Kadur / Rock / Malabar pit viper (Trimeresurus malabaricus) perfectly camouflaged in roots of a streamside tree, Western Ghats, Southern India

Sandesh Kadur / Rock / Malabar Pit viper (Trimeresurus malabaricus) Western Ghats, Southern India

Sandesh Kadur / Malabar rock pit viper (Trimeresurus malabaricus) and Common vine snake (Ahaetulla nasuta) found in Western Ghats, Southern India. digital composite

Pete Oxford / Halys Viper (Gloydius halys), Gobi Desert, Mongolia

Rod Williams / Armenian viper (Vipera raddei) captive, from Armenia, Iran, Turkey

Pete Oxford / Canebrake or Timber rattlesnake juvenile (Crotalus horridus) USA, captive

Pete Oxford / Timber rattlesnake (Crotalus horridus) yellow morph near hibernation den, Northern Georgia, USA, manipulated

Pete Oxford / Timber rattlesnakes (Crotalus horridus) black and yellow morphs, near hibernation den, Northern Georgia, USA, manipulated

Pete Oxford / Timber rattlesnake (Crotalus horridus) black morph near hibernation den, Northern Georgia, USA, manipulated

Pete Oxford / Timber rattlesnakes (Crotalus horridus) black and yellow morphs near hibernation den, Northern Georgia, USA, manipulated

Pete Oxford / Eastern diamondback rattlesnake (Crotalus adamanteus) close up of skin detail, The Orianne Indigo Snake Preserve, Telfair County, Georgia USA, captive

Pete Oxford / Canebrake or Timber rattlesnake juvenile (Crotalus horridus) USA, captive

Pete Oxford / Pigmy rattlesnake (Sistrurus miliarius) close up of coiled snake, captive

Pete Oxford / Eastern diamondback rattlesnake (Crotalus adamanteus) Orianne Indigo Snake Preserve, Telfair County, Georgia, USA, captive

Pete Oxford / Eastern diamondback rattlesnake (Crotalus adamanteus) close up of cloaca, belly and tail scales, captive

Chien Lee / Sabah Bamboo Pitviper (Popeia sabahi), Sarawak, Borneo, Malaysia

Chien Lee / Sabah Bamboo Pitviper (Popeia sabahi), Sarawak, Borneo, Malaysia

Luis Quinta / Baskian viper (Vipera seoanei) on rock, Geres National Park, Portugal, September.

Alex Hyde / Asp viper (Vipera aspis) female, amongst dead bracken, Midi-Pyrenees, France, August.

Alex Hyde / Asp viper (Vipera aspis) female, amongst dead bracken, Midi-Pyrenees, France, August.

Alex Hyde / Asp viper (Vipera aspis) female, photographed on a white background, Midi-Pyrenees, France, August.

Alex Hyde / Asp viper (Vipera aspis) female, photographed on a white background, Midi-Pyrenees, France, August.

Alex Hyde / Asp viper (Vipera aspis) female, photographed on a white background, Midi-Pyrenees, France, August.

Alex Hyde / Asp viper (Vipera aspis) female, photographed on a white background, Midi-Pyrenees, France, August.

Luis Quinta / Baskian viper (Vipera seoanei) on moss covered rock, Geres National Park, Portugal, September.

Luis Quinta / Baskian viper (Vipera seoanei) on rock, Geres National Park, Portugal, September.

Luis Quinta / Baskian viper (Vipera seoanei) on rock, Geres National Park, Portugal, September.

Luis Quinta / Baskian viper (Vipera seoanei) Geres National Park, Portugal, September.

Luis Quinta / Baskian viper (Vipera seoanei) Geres National Park, Portugal, September.

Luis Quinta / Baskian viper (Vipera seoanei) Geres National Park, Portugal, September.

Bert Willaert / Hognosed Pit Viper (Porthidium nasutum) coiled. Ecuador, South America.

Bert Willaert / Green Tree Viper (Atheris chlorechis) in its landscape. Atewa Forest Reserve, Ghana, September.

John Cancalosi / Side-striped Palm-pitviper (Bothriechis lateralis) coiled in strike pose. Costa Rica. Captive.

John Cancalosi / Side-striped Palm-pitviper (Bothriechis lateralis) coiled in strike pose with tongue extended. Costa Rica. Captive.

John Cancalosi / Side-striped Palm-pitviper (Bothriechis lateralis) coiled in strike pose. Costa Rica. Captive.

John Cancalosi / Side-striped Palm-pitviper (Bothriechis lateralis) coiled in strike pose. Costa Rica. Captive.

John Cancalosi / Side-striped Palm-pitviper (Bothriechis lateralis) coiled in strike pose. Costa Rica. Captive.

Hanne & Jens Eriksen / Saw scaled viper (Echis carinatus) with tongue out, captive, Oman, February

Hanne & Jens Eriksen / Sind saw scaled viper (Echis carinatus sochureki) captive, head pattern, Oman, February

Hanne & Jens Eriksen / Sind saw scaled viper (Echis carinatus sochureki) curled up, captive, Oman, February

Hanne & Jens Eriksen / Sind saw scaled viper (Echis carinatus sochureki) captive, Oman, February

Hanne & Jens Eriksen / Sind saw scaled viper (Echis carinatus sochureki) captive, Oman, February

Adrian Davies / Viper's Bugloss (Echium vulgare) flowers, UK

James Christensen / Ecuadorian Toad-headed Pit-viper (Bothrocophias campbelli) eye and pit sensory organ, Mindo, western slope of Andes, Ecuador

Kevin Schafer / Banded Pit Viper (Trimeresurus fasciatus), Tompotika Peninsula, central Sulawesi, Indonesia

James Christensen / Osborne's Lancehead (Bothrops osbornei) juvenile, western slope of Andes, Ecuador

James Christensen / Ecuadorian Toad-headed Pit-viper (Bothrocophias campbelli) held up by photographer's assistant, Shannon Bowley, Mindo, western slope of Andes, Ecuador

James Christensen / Ecuadorian Toad-headed Pit-viper (Bothrocophias campbelli), Mindo, western slope of Andes, Ecuador

Alex Hyde / Wide angle view of Common Swallowtail Butterfly (Papilio machaon) on Viper's Bugloss / Blueweed (Echium vulgare) in alpine meadow. Nordtirol, Tirol, Austrian Alps, Austria, 1700 metres altitude, July.

Alex Hyde / Wide angle view of Common Swallowtail Butterfly (Papilio machaon) resting on Viper's Bugloss / Blueweed (Echium vulgare) in alpine meadow. Nordtirol, Tirol, Austrian Alps, Austria, 1700 metres altitud...

Alex Hyde / Common Swallowtail Butterfly (Papilio machaon) resting on Viper's Bugloss / Blueweed (Echium vulgare) in alpine meadow. Nordtirol, Tirol, Austrian Alps, Austria, 1700 metres altitude, July.

Sandesh Kadur / Jerdon's Pit-Viper (Protobothrops jerdonii) with tongue exposed, Ziro valley, Arunachal Pradesh, India

Grzegorz Lesniewski / Mountain Viper's Grass (Podospermum rosea) in flower. Bieszczady National Park, the Carpathians, Poland, July.

Klaus Echle / Black Viper / Adder (Vipera berus) portrait. Black Forest, Germany, June.

Piotr Naskrecki / Rhinoceros Adder (Bitis nasicornis) camouflaged in leaf litter, Ghana