Scientific Classification

KINGDOM: Animalia

PHYLUM: Chordata

CLASS: Reptilia

ORDER: Squamata

FAMILY: Helodermatidae

GENUS: Heloderma

SPECIES: H. suspectum

Conservation Status

Gilamonster / Heloderma suspectum
Close-up shot of a gila monster under the cactus
The Gila monster (Heloderma suspectum) - venomous lizard is lifting his feet high and pokes tongue
Gila Monster on rocks

Not only is the Gila monster the largest lizard native to North America but is also the only venomous lizard native to the United States! With its tail making up 20 % of its body length, the Gila monster can grow up to two feet long and weigh anywhere from 1-5 pounds.

The Gila monsters are covered in beads called osteoderms instead of scales, and their bright colors are used to ward off predators. Even though the Gila monster is venomous, it poses little threat to us as they are so sluggish.

The Gila monster lacks hollow teeth and the jaw strength to directly inject its venom. Instead, the venom comes from its salivary glands and is released through chewing. The Gila monster’s venom is incredibly complex; however, there have been no recorded fatalities in humans. In fact, scientists have started isolating and running tests on one of the toxins to help treat type 2 diabetes.
The Gila monster can be found in the southwestern parts of the United States and northwestern part of Mexico, preferring to live in arid rocky deserts such as the Mojave or Sonoran deserts.
The Gila monster spends much of its time hidden in burrows but will come out to eat or mate. Its diet consists of easy prey such as eggs, small mammals, and small birds. Amazingly, Gila monsters eat less than 10 times per year, but when they do, they can eat up to one-third of its own body weight. It’s able to hunt not only using its keen sense of sight, but also by flicking its tongue out to pick up scent particles in the air.
Gila monsters are solitary critters but come together in large groups for the mating season in April to June. A couple of months after mating, the females will lay 2-12 eggs and bury them in the sand. After nine months, the eggs will hatch and look like miniature versions of an adult Gila monster, but they have larger colored bands. The hatchlings can even bite and produce venom upon hatching!

Gila monsters are named after the Gila River Basin in Arizona, where they were first discovered. They have one living relative which is the Mexican beaded lizard that is also venomous.