Michael D. Kern / Gila monster (Heloderma suspectum) captive, from USA

Tom Vezo / Gila Monster (Heloderma suspectum), Sonoran Desert, Arizona

Michael D. Kern / Zoo Atlanta / Guatamelan Beaded Lizard {Heloderma horridum charlesbogerti} captive, Guatemala

ZSSD / Gila Monster (Heloderma suspectum) sensing with tongue, venomous species native to southwest United States and northern Mexico

Mark Carwardine / Gila monster resting in shade {Heloderma suspectum} California, USA

Mark Carwardine / Gila monster {Heloderma suspectum} captive, from central America

Mark Carwardine / Gila monster {Heloderma suspectum} captive, from Central America

Daniel Heuclin / Gila monster (Heloderma suspectum suspectum) controlled conditions, Catalina mountains foothills, Arizona USA

Daniel Heuclin / People observing Gila monster (Heloderma suspectum suspectum) controlled conditions, Catalina mountains foothills, Arizona USA

Daniel Heuclin / Gila monster (Heloderma suspectum suspectum) controlled conditions, Catalina mountains foothills, Arizona USA

Daniel Heuclin / Gila monster (Heloderma suspectum) eating eggs, Near Tucson, Arizona, USA captive

Daniel Heuclin / Man photographing Gila monster (Heloderma suspectum suspectum) controlled conditions, Organ Pipe Cactus Monument, Arizona USA

Barry Mansell / Gila Monster (Heloderma suspectum) in banded phase. Arizona, USA, September.

Daniel Heuclin / Gila monster (Heloderma suspectum) studio shot, captive, from Arizona, USA

Pete Oxford / Gila Monster (Heloderma suspectum) flicking tongue, native to the southwestern United States and northwestern Mexico

John Cancalosi / Gila monster (Heloderma suspectum) Sonoran desert, Arizona, USA

John Cancalosi / Gila monster (Heloderma suspectum) at entrance to burrow, Sonoran desert, Arizona, USA

John Cancalosi / Gila monster (Heloderma suspectum) defensive behaviour, Sonoran desert, Arizona, USA

John Cancalosi / Gila monster (Heloderma suspectum) Sonoran desert, Arizona, USA

Mark Carwardine / Mexican beaded lizard (Heloderma horridum) captive, from Central America

Mark Carwardine / Mexican beaded lizard (Heloderma horridum) captive, from Central America

Michael D. Kern / Gila monster (Heloderma suspectum) in habitat, USA

Michael D. Kern / Gila monster (Heloderma suspectum) USA

Michael D. Kern / Mexican beaded lizard (Heloderma horridum) captive, from Central America

Albert Lleal / Gila Monster (Heloderma suspectum) young in threatening pose, native to south west United states and northern Mexico

John Cancalosi / Rio Fuerte Beaded Lizard (Heloderma horridum exasperatum) Sonora, Mexico Venomous species

John Cancalosi / Rio Fuerte Beaded Lizard (Heloderma horridum exasperatum) Sonora, Mexico Venomous species

Miles Barton / Mexican / Guatemalan beaded lizards (Heloderma horridum charlesbogerti) males wrestling. Captive

Miles Barton / Mexican / Guatemalan beaded lizards (Heloderma horridum charlesbogerti) males wrestling. Captive

Michael D. Kern / Guatemalan Beaded Lizard {Heloderma horridum charlesbogerti} climbing a tree, Montagua Valley, Guatemala Venomous species

Michael D. Kern / Guatemalan Beaded Lizard {Heloderma horridum charlesbogerti} in habitat, Montagua Valley, Guatemala

Michael D. Kern / Guatemalan Beaded Lizard {Heloderma horridum charlesbogerti} climbing a tree, Montagua Valley, Guatemala Venomous species

Tom Vezo / Gila Monster (Heloderma suspectum), Sonoran Desert, Arizona

Tom Vezo / Gila Monster (Heloderma suspectum) walking, Sonoran Desert, Arizona

Tom Vezo / Gila Monster (Heloderma suspectum) flicking tongue, Sonoran Desert, Arizona

Tom Vezo / Gila Monster (Heloderma suspectum), Sonoran Desert, Arizona

Rod Williams / Gila monster {Heloderma suspectum} captive, from USA and Mexico

Michael D. Kern / Zoo Atlanta / Guatamelan Beaded Lizard {Heloderma horridum charlesbogerti} flicking fork tongue, captive, Guatemala

Michael D. Kern / Zoo Atlanta / Guatamelan Beaded Lizard {Heloderma horridum charlesbogerti} portrait in tree, Guatemala

Patricio Robles Gil / Gila Monster (Heloderma suspectum) adult in the Sonoran Desert, venomous species, Mexico

Barry Mansell / Gila monster (Heloderma suspectum) hissing in defense, Arizona, USA.

John Cancalosi / Gila monster, Sonoran desert {Heloderma suspectum} Arizona, USA, captive

Tom Vezo / Gila monster {Heloderma suspectum} Arizona, USA.

John Cancalosi / Gila monsters at entrance to burrow {Heloderma suspectum} Arizona, USA.

Tom Vezo / Gila monster {Heloderma suspectum} Arizona, USA.

John Cancalosi / Gila monster {Heloderma suspectum} in Saguaro cactus stem Arizona USA

Barry Mansell / Mexican beaded lizard {Heloderma horridum} Sonora, Mexico

John Cancalosi / Gila monster (Heloderma suspectum). Sonoran desert, Arizona, USA

Pete Oxford / Gila Monster (Heloderma suspectum), native to the southwestern United States and northwestern Mexico

John Cancalosi / Gila monster {Heloderma suspectum} Sonoran desert, Arizona USA, captive

Rod Williams / Mexican beaded lizard portrait {Heloderma horridum} captive native to Mexico