Stephen Belcher / Komodo Dragon (Varanus komodoensis) with tongue fully extended, Rinca Island, Komodo National Park, Indonesia

Stephen Belcher / Komodo Dragon (Varanus komodoensis) standing on hind legs, Rinca Island, Komodo National Park, Indonesia

Stephen Belcher / Komodo Dragon (Varanus komodoensis) displaying, Rinca Island, Komodo National Park, Indonesia

Stephen Belcher / Komodo Dragon (Varanus komodoensis) standing on hind legs, Rinca Island, Komodo National Park, Indonesia

Stephen Belcher / Komodo Dragon (Varanus komodoensis), Rinca Island, Komodo National Park, Indonesia

Stephen Belcher / Komodo Dragon (Varanus komodoensis), Rinca Island, Komodo National Park, Indonesia

Rod Williams / Green / Emerald Tree Monitor (Varanus prasinus) head portrait climbing tree trunk, captive.

Sergey Gorshkov / Leopard (Panthera pardus) in tree near a Monitor Lizard (Varanus sp), Botswana

Mark Carwardine / Nile monitor (Varanus niloticus) resting on branch, captive, from Africa

Suzi Eszterhas / Nile Monitor (Varanus niloticus) climbing over rock pile, Mala Mala Reserve, South Africa

Vincent Grafhorst / White-throated Monitor (Varanus albigularis) lizard emerging from burrow, Makgadikgadi, Botswana

Miles Barton / Sir David Attenborough with Argus monitor (Varanus panoptes rubidus) standing on its hind legs when approached, Western Australia. November 2006, on location filming for BBC NHU series 'Life in Cold B...

Edwin Giesbers / Close up of eye of Gould's / Sand monitor {Varanus gouldii} captive

Suzi Eszterhas / Nile Monitor (Varanus niloticus) swimming, Ngamba Island Chimpanzee Sanctuary, Lake Victoria, Uganda

Suzi Eszterhas / Nile Monitor (Varanus niloticus), Ngamba Island Chimpanzee Sanctuary, Lake Victoria, Uganda

Suzi Eszterhas / Nile Monitor (Varanus niloticus), Ngamba Island Chimpanzee Sanctuary, Lake Victoria, Uganda

Suzi Eszterhas / Nile Monitor (Varanus niloticus), Ngamba Island Chimpanzee Sanctuary, Lake Victoria, Uganda

Miles Barton / David Attenborough observing an Argus monitor lizard (Varanus panoptes rubidus) Western Australia, November 2006, on location for BBC NHU series 'Life in Cold Blood' This species of monitor rears up...

Miles Barton / David Attenborough observing an Argus monitor lizard (Varanus panoptes rubidus) Western Australia, November 2006, on location for BBC NHU series 'Life in Cold Blood' This species of monitor rears up...

Chien Lee / Bengal Monitor (Varanus bengalensis), Jakarta, Indonesia

GEORGETTE DOUWMA / Monitor lizard {Varanus salvator} emerging from turtle nest after eating eggs, Sabah

Jabruson / Close up of foot of Water / Nile monitor lizard {Varanus niloticus} Epulu Ituri Rainforest Reserve, Dem Rep of Congo

Jabruson / Close up of skin of Water / Nile monitor lizard {Varanus niloticus} Epulu Ituri Rainforest Reserve, Dem Rep of Congo

Tim Laman / Asian / Common Water Monitor (Varanus salvator) amongst mangrove roots on a river bank, Sundarban Forest, Khulna Province, Bangladesh.

Tim Laman / Asian / Common Water Monitor (Varanus salvator) amongst mangrove roots on a river bank, Sundarban Forest, Khulna Province, Bangladesh.

Tim Laman / Asian / Common Water Monitor (Varanus salvator) amongst mangrove roots on a river bank, Sundarban Forest, Khulna Province, Bangladesh.

Tim Laman / Asian / Common Water Monitor (Varanus salvator) amongst mangrove roots on a river bank, Sundarban Forest, Khulna Province, Bangladesh.

Mary McDonald / Savannah monitor lizard {Varanus exanthematicus} flicking out its blue tongue, Samburu reserve, Kenya

Mary McDonald / Savannah monitor lizard {Varanus exanthematicus} walking across barren soil in Samburu NP, Kenya

Mary McDonald / Savannah monitor lizard {Varanus exanthematicus} Samburu reserve, Kenya

Steven David Miller / Perentie (Varanus giganteus) adult tasting the air with its tongue, Point Quobba, Carnarvon, Western Australia, November

Steven David Miller / Perentie (Varanus giganteus) adult sunning on rocks, Point Quobba, Carnarvon, Western Australia, November

Steven David Miller / Perentie (Varanus giganteus) juvenile, very aggressive, captive, Alice Springs Reptile Centre, Northern Territory, Australia

Steven David Miller / Mertens water monitor {Varanus mertensi} peering out from resting hole in log, tongue exposed, Lake Kununurra, Western Australia

Steven David Miller / Mertens water monitor {Varanus mertensi} swimming away from resting hole in log, Lake Kununurra, Western Australia

Steven David Miller / Mertens water monitor {Varanus mertensi} sunning on shore, Lake Kununurra, Western Australia

Steven David Miller / Mertens water monitor {Varanus mertensi} sunning on log on shore, Lake Kununurra, Western Australia

Steven David Miller / Perentie (Varanus giganteus) adult sunning on rocks, Point Quobba, Carnarvon, Western Australia, November

Steven David Miller / Perentie (Varanus giganteus) juvenile, very aggressive, captive, Alice Springs Reptile Centre, Northern Territory, Australia

Steven David Miller / Perentie (Varanus giganteus) adult sunning on rocks, Point Quobba, Carnarvon, Western Australia, November

Rod Williams / Philippine water monitor (Varanus cumingi) captive, from the Philippines

Steven David Miller / Mertens water monitor {Varanus mertensi} peering out from resting hole in log, Lake Kununurra, Western Australia

Steven David Miller / Mertens water monitor {Varanus mertensi} swimming near shore, Lake Kununurra, Western Australia

Rod Williams / Male Komodo dragon (Varanus komodoensis) captive, from Komodo Island, Indonesia, Vulnerable species

Steven David Miller / Mertens water monitor {Varanus mertensi} sunning, Merten's Falls, Mitchell River National Park, Western Australia

Bernard Castelein / Common Indian / Bengal monitor (Varanus bengalensis), head portrait, Keoladeo Ghana / Bharatpur NP, Rajasthan, India

Juan Carlos Munoz / Asian water monitor lizard (Varanus salvator) on forest floor, Rio Sungai Kinabatangan, Sabah, Borneo, Malaysia

Juan Carlos Munoz / Asian water monitor lizard (Varanus salvator) on forest floor, Rio Sungai Kinabatangan, Sabah, Borneo, Malaysia

Juan Carlos Munoz / Asian water monitor lizard (Varanus salvator) in river, Rio Sungai Kinabatangan, Sabah, Borneo, Malaysia

Jouan & Rius / Variegated lizard / Lace monitor (Varanus varius), Central Australia, Australia

Jouan & Rius / Variegated lizard / Lace monitor (Varanus varius) Central Australia, Australia

Jouan & Rius / Variegated / Lace monitor (Varanus varius) looking up tree trunk, Central Australia, Australia

Jouan & Rius / Variegated lizard / Lace monitor (Varanus varius), Central Australia, Australia

Jouan & Rius / Variegated lizard / Lace monitor (Varanus varius), Central Australia, Australia

Robert Valentic / Gould's monitor {Varanus gouldii} male basking adjacent to burrow amongst desert rocks, Innamincka, South Australia

Norbert Wu / Komodo Dragon (Varanus komodoensis) on beach, Komodo Island, Indonesia

Norbert Wu / Komodo Dragon (Varanus komodoensis) on beach, Komodo Island, Indonesia

Tony Heald / Asian Water Monitor [Varanus salvator] portrait with tongue exposed, Sukau, Sabah, Borneo, September

Tim Laman / Asian water monitor lizard (Varanus salvator) swimming across the river with a small grasshopper on its head. Kinabatangan Wildlife Sanctuary, Sabah, Malaysia, Borneo.

Tim Laman / Asian water monitor lizard {Varanus salvator} Lower Kinabatangan Wildlife Sanctuary, Sabah, Borneo, Malaysia

Robert Valentic / Gould's monitor / Sand goanna {Varanus gouldii} juvenile foraging for lizards on Gibber Plain, Pimba, South Australia

Robert Valentic / Black headed monitor {Varanus tristis tristis} juvenile with body lowered and frozen to avoid detection by a raptor flying above, West Australia

Robert Valentic / Black headed monitor {Varanus tristis tristis} male threat display, Queensland, Australia

Robert Valentic / Storr's monitor / goanna {Varanus storri} male, Queensland, Australia

Robert Valentic / Variegated / lace monitor lizard {Varanus varius} female searching for nesting birds, South Australia

Jason Venus / Desert monitor (Varanus griseus) Sahara desert

Sharon Heald / Water monitor lizard {Varanus niloticus} leaving nest after raiding bird nest in a riverbank, Chobe National Park, Botswana

Nick Garbutt / Asian water Monitor (Varanus salvator), Kinabatangan River, Sabah, Borneo

Steven David Miller / Heath Monitor {Varanus rosenbergi} foraging in burnt heathland, Summer, Cape Le Grand National Park, Western Australia

Philippe Clement / Nile monitor {Varanus niloticus} sitting on rock, Kruger NP, South Africa

Philippe Clement / Southern Savanna Monitor {Varanus albigularis} climbing tree stump, Kruger NP, South Africa

ZSSD / Blue-tailed Monitor (Varanus doreanus) eye, native to New Guinea

PREMAPHOTOS / Nile monitor lizard {Varanus niloticus} basking on rock, South Africa

PREMAPHOTOS / Two Nile monitor lizards {Varanus niloticus} interacting in forest pool, Gambia

Michael D. Kern / Dumeril monitor {Varanus dumerilii} captive, occurs south east Asia

Anup Shah / Nile monitor {Varanus niloticus} resting in tree, Katavi NP, Tanzania

Tony Phelps / Scientist handling Southern savanna / rock monitor lizard {Varanus albigularis} Little Karoo, South Africa

Tony Phelps / Southern savanna / rock monitor lizard {Varanus albigularis} male, Little Karoo, South Africa

Jurgen Freund / Komodo dragon faeces (Varanus komodoensis) Komodo Island, Indonesia

Juergen Freund / Komodo dragon captured for research (Varanus komodoensis) Komodo Island, Indonesia

Jurgen Freund / Komodo dragon captured for research (Varanus komodoensis) Komodo Island, Indonesia

Juergen Freund / Komodo dragon faeces being held in hand (Varanus komodoensis) Komodo Island, Indonesia

Juergen Freund / Komodo dragon saliva sample for research (Varanus komodoensis) Komodo Island, Indonesia

Piotr Naskrecki / Nile Monitor (Varanus niloticus) juvenile climbing on branch, Africa

Robert Valentic / Ridge tailed monitor lizard, male basking {Varanus acanthurus} Western Australia

Robert Valentic / Freckled monitor lizard, male {Varanus tristis orientalis} Northern Territory, Australia

Robert Valentic / Black headed monitor lizard, male {Varanus tristis tristis} Western Australia

ZSSD / Komodo Dragon (Varanus komodoensis) close-up of eye and skin

Bernard Castelein / Bengal monitor lizard {Varanus bengalensis} in tree, Keoladeo Ghana, Bharatpur NP, Rajasthan, India

Robert Valentic / Spencer's monitor, gravid female {Varanus spenceri} Northern Territory, Australia

Robert Valentic / Rosenberg's monitor, male threat display {Varanus rosenbergi} South Australia

James Aldred / Desert monitor lizard {Varanus griseus} Morocco, 1997

Jurgen Freund / Komodo dragon smelling air with tongue (Varanus komodoensis) Komodo Island, Indonesia

Jurgen Freund / Komodo dragon walking along beach (Varanus komodoensis) smelling air with tongue, Komodo Island, Indonesia

Jabruson / Savanna monitor lizard (Varanus exanthematicus) killed in hot springs, Lake Bogoria, Kenya

Pete Oxford / Nile monitor (Varanus niloticus) raiding Carmine Bee-eater nests in rock face, Botswana