Morley Read / Tropical flat snake (Siphlophis compressus) climbing on a flowering bromeliad (Aechmea) in the Amazon rainforest, Orellana Province, Ecuador.

Morley Read / Slow motion clip of a Forest whiptail lizard (Kentropyx pelviceps) blinking its eye, showing nictitating membrane crossing the eye, Amazon rainforest, Orellana Province, Ecuador.

Morley Read / Slow motion clip of a Linnaeus' sipo snake (Chironius exoletus) with open mouth, part of threat display, Amazon rainforest, Orellana Province, Ecuador.

Morley Read / Parrot snake (Leptophis ahaetulla) threat display, Amazon rainforest, Orellana Province, Ecuador.

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

David Tipling / Common European adder (Vipera berus) two males fighting over a female. Holt, North Norfolk, England, UK. April

David Tipling / Common European adder (Vipera berus) two males fighting over a female, Holt, North Norfolk, England, UK. April

David Tipling / Common European adder (Vipera berus) two males fighting over a female, Holt, North Norfolk, England, UK. April.

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

Fabio Pupin / Ruwenzori side-striped chameleon, (Trioceros rudis), hanging from fern, Nyungwe Forest NP, Rwanda, December . Non-ex.

Fabio Pupin / Moorish gecko, (Tarentola mauritanica), hunting on window, Italy, April . Non-ex.

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

Robert Valentic / Central bearded dragon (Pogona vitticeps) basking in mallee / heathland habitat on the Murrayville Track in the Big Desert Wilderness of north-western Victoria, Australia.

Robert Valentic / Heath Monitor (Varanus rosenbergi) male enacting a threat display, in mallee/heath habitat near Pinnaroo, South Australia.

Robert Valentic / Rough-scaled death adder (Acanthophis rugosus) waving tip of tail as a lure to entice prey within striking range. Mount Isa, Queensland Australia.

Robert Valentic / Striped legless lizard (Delma impar) female, in volcanic plain near Reedesdale in central Victoria, Australia.

Lucas Bustamante / Marine Iguanas (Amblyrhynchus cristatus) basking. Fernandina Island, Galapagos Islands.

John Shaw / Namaqua chameleon (Chamaeleo namaquensis) catching larvae with its extended tongue. In the Namib desert near Swakopmund, Namibia.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus), Punta Vicente Roca, Isabela Island, Galapagos

Tui De Roy / Marine iguanas (Amblyrhynchus cristatus) fighting, Punta Vicente Roca, Isabela Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) group on rocks, Cape Douglas, Fernandina Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus), Punta Espinosa, Fernadina Island, Galapagos

Daniel Heuclin / Horned viper (Vipera ammodytes) in natural setting, Turkey.

John Chan / Two male Southern Pacific rattlesnakes (Crotalus oreganus helleri) fighting during mating season. This behaviour is known as a "combat dance", and is used to determine dominance and the right to mate...

Robert Valentic / Eastern brownsnake (Pseudonaja textilis) juvenile. Australia.

Robert Valentic / Coastal taipan (Oxyuranus scutellatus) tasting air, Julatten, north Queensland, Australia,

Robert Valentic / Lowland blotched blue-tongue (Tiliqua nigrolutea) on a coastal bluff in the Bay of Fires region of north-eastern Tasmania, Australia, spring.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) starved to death due to El Nino effect, Puerto Ayora / Academy Bay, Santa Cruz Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) on shore, Punta Moreno, Isabela Island, Galapagos

Steven David Miller / A Perentie (Varanus giganteus) using its forked tongue to detect smells, Alice Springs Reptile Centre, Northern Territory, Australia, Captive. May.

Robert Valentic / Eastern tiger snake (Notechis scutatus) female, Yarra River corridor in suburban Melbourne, Victoria, Australia, in mid-summer. She is in a defensive pre-strike position with hood expanded, accompanie...

Robert Valentic / Red-bellied Blacksnake (Pseudechis porphyriacus) basking on rock, Lerderderg Gorge, Victoria, Australia, February.

David Gallan / Lace monitor (Varanus varius) sensing with tongue, New South Wales, Australia, December.

Robert Valentic / Phuket horned tree lizard (Acanthosaura phuketensis) near Bang Pae Waterfall, Khao Phra Thaew NP, Phuket Island, Thailand.

Robert Valentic / Portrait of an adult Three-toed Earless Skink (Hemiergis talbingoensis) Tallarook, Goulburn River in central Victoria, Australia.

Robert Valentic / Monocled cobra (Naja kaouthia) on rubber plantation at Phak Lok, Phuket Island, Thailand .

Guy Edwardes / Mozambique spitting cobra (Naja mossambica) spitting venom. Kruger, South Africa. Controlled conditions.

Nick Hawkins / Marine iguana (Amblyrhynchus cristatus) basking on volcanic rock at coast. Isabela Island, Galapagos.

Paul Hobson / Parrot snake (Leptophis ahaetulla) in aggressive pose with mouth open. Costa Rica.

Franco Banfi / Close view of a Green anaconda, (Eunectes murinus) underwater, Formoso River, Bonito, Mato Grosso do Sul, Brazil

Tui De Roy / Galapagos lava lizard (Microlophus albemarlensis) sitting on Marine iguana (Amblyrhynchus cristatus) Punta Espinosa, Fernandina Island, Galapgos.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) in water, Puerto Egas, Santiago Island, Galapagos

Tui De Roy / Marine iguanas (Amblyrhynchus cristatus) silhouettes at sunset, Punta Vicente Roca, Isabela Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) males in breeding colouration on rocks, with sun halo, Floreana Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) group on rock in the waves, Cape Hammond, Fernandina Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) swimming underwater, Sullivan Bay, Santiago Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) in the surf, Black Beach, Floreana Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) peering over rocks, Punta Espinosa, Fernandina Island, Galapagos

Lucas Bustamante / Red tailed boa constrictor (Boa constrictor constrictor) juvenile, portrait, with tail wrapped round head, Cuayabeno, Sucumbios, Ecuador.

Lucas Bustamante / Pinocchio lizard (Anolis proboscis) male on stem, Mindo, Pichincha, Ecuador, Endangered species.

Lucas Bustamante / Mosquito (Culicidae) feeding on the back of an Equatorial anole (Anolis aequatorialis) Mindo, Pichincha, Ecuador.

Brian Bevan / Male Jackson's chameleon (Trioceros jacksonii) on a branch, looking around with turret eyes, UK. Captive, native to East Africa.

Philippe Clement / Panther chameleon (Furcifer pardalis) in tree, showing rotating eyes. Captive, native to Madagascar.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) submerged in salty pools to avoid mosquitoes, Santa Cruz Island, Galapagos.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) two on beach, Santa Cruz Island, Galapagos.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) swimming underwater, Fernandina Island, Galapagos.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus), male in full breeding colours Floreana Island, Galapagos.

Brian Bevan / Juvenile Jackson's chameleon (Chamaeleo jacksonii xantholophus) feeding, flicking tongue to catch insects. Captive.

Christophe Courteau / Peringuey's adder (Bitis peringueyi) buried in sand, flicking tongue, hunting, Namib Desert, Namibia.

Sandesh Kadur / Bengal monitor (Varanus bengalensis) smelling a stone with its tongue, Ranthambore National Park, Rajasthan, India. 2016.

Sandesh Kadur / Two Bengal monitors (Varanus bengalensis) fighting, Ranthambore National Park, Rajasthan, India. 2016.

Tony Phelps / Cape cobra (Naja nivea) spreading its hood, retreats into hole, De Hoop Nature Reserve, Western Cape, South Africa, January.

Tony Phelps / Cape cobra (Naja nivea) emerging from a Cape gerbil (Gerbilliscus afra) burrow, hunting and smelling with its tongue, De Hoop Nature Reserve, Western Cape, South Africa, January.

Tony Phelps / Cape cobra (Naja nivea) hunting, chasing a Cape gerbil (Gerbilliscus afra), De Hoop Nature Reserve, Western Cape, South Africa, December.

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

John Cancalosi / Western diamondback rattlesnake (Crotalus atrox), defensive rattling, Arizona, USA, April.

John Cancalosi / Group of gravid female Timber rattlesnakes (Crotalus horridus) basking before giving birth, Pennsylvania, USA, July.

Sandesh Kadur / King cobra (Ophiophagus hannah) cannibalism, male swallowing a female, Agumbe, Karnartaka, India.

Sandesh Kadur / Close up of King cobra (Ophiophagus hannah) cannibalism, male swallowing a female, Agumbe, Karnartaka, India.

Sandesh Kadur / Two male King cobras (Ophiophagus hannah) fighting, Agumbe, Karnartaka, India.

John Cancalosi / Female Timber rattlesnake (Crotalus horridus) at nest site with newborn young, Pennsylvania, USA, September.

Tony Phelps / Puff adder (Bitis arietans) moving into ambush position under a bush, DeHoop Nature Reserve, Western Cape, South Africa, January.

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

Daniel Heuclin / Blue iguana (Cyclura lewisi) captive, endangered species occurs in Cayman Islands.

Colin Varndell / Grass snake (Natrix natrix) Dorset, UK May

Juan Carlos Munoz / Namib sand snake (Psammophis namibensis) in sand dunes, Swakopmund, Erongo Region, Namibia.

Matthew Maran / Grass snake (Natrix natrix) flicking tongue, Hampstead Heath, London, England, UK, August.

Bence Mate / Green / Double-crested basilisk (Basiliscus plumifrons) running across water surface, Santa Rita, Costa Rica.

Bence Mate / Satiny Parrot snake (Leptophis depressirostris) Santa Rita, Costa Rica.

Bence Mate / Lowland forest racer (Dendrophidion vinitor) Laguna del Lagarto, Santa Rita, Costa Rica

Laurie Campbell / Common / Viviparous lizard (Zootoca vivipara) mother with young. Burnmouth, Berwickshire, England, UK.

Roy Mangersnes / Marine iguana (Amblyrhynchus cristatus) resting on log in sunlight, Fernandina Island, Galapagos, April.

Roy Mangersnes / Marine iguana (Amblyrhynchus cristatus) feeding in deep water to find algae, off the coast of Fernandina island on Galapagos. April 2016. Much of the algae on coast and at shallower depths have been k...

Roy Mangersnes / Marine iguana (Amblyrhynchus cristatus) feeding in deep water to find algae, off the coast of Fernandina island on Galapagos. April 2016. Much of the algae on coast and at shallower depths have been k...

Roy Mangersnes / Marine iguanas (Amblyrhynchus cristatus) basking on rock next to skeleton of one which starved to death. Unusually warm El Nino waters have killed a lot of the algae which is the food for these iguana...

Roy Mangersnes / Coastal scene on Fernandina Island, with small group of Marine iguanas (Amblyrhynchus cristatus). Galapagos. April 2016. Normally there would be a much larger group but El Nino weather has killed off...

Roy Mangersnes / Dead Marine iguana (Amblyrhynchus cristatus) on the coastal rocks on Santiago Island, Galapagagos, April 2016. It probably died of starvation as much of the algae in the region have died off due to un...

Luis Quinta / Grass snake (Natrix natrix) juvenile playing dead, Alvao, Portugal, April.

Luis Quinta / Grass snake (Natrix natrix) swimming in river, Olo, Alvao, Portugal, June.

Mark MacEwen / Komodo dragon (Varanus komodoensis) with tongue on out beach, Komodo National Park, the islands of Komodo, Indonesia. Vulnerable species.

Mark MacEwen / Komodo dragon (Varanus komodoensis) walking with tongue extended on beach, found in the islands of Komodo, Indonesia. Vulnerable species.

Mark MacEwen / Komodo dragon (Varanus komodoensis) with tongue extended on beach, Komodo National Park, Indonesia. Vulnerable species.

Morley Read / Tropical flat snake (Siphlophis compressus) descending down a vine, with Rio Tiputini in the background, Orellana Province, Ecuador.

Morley Read / Brown-banded water snake (Helicops angulatus) swallowing a Basin treefrog (Boana lanciformis) in a pool full of tadpoles in rainforest, Orellana Province, Ecuador.