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Gila Monster

Heloderma suspectum

Gila Monster at Henry Vilas Zoo

About Gila Monster

The Gila monster is the largest lizard native to the United States. This species was named after the Gila River Basin in Arizona, where they were first discovered.


The Gila monster lives in Arizona, New Mexico, Mexico, southwestern Utah, and southern Nevada. They live in dry areas including rocky slopes and canyon bottoms, typically near streams. They spend about 95% of their time underground and emerge to hunt and sunbathe.


They eat small mammals, young rabbits, mice, squirrels, birds, lizards, and eggs (of birds, lizards, snakes, turtles, and tortoises). Gila monsters can consume as much as 35% to 50% of their body weight. That’s the same as a 175 lb person eating 50 to 85 lbs of food at ONE MEAL! This is helpful in an environment where food is difficult to find. They store fat in their large tails which means they don’t need to eat very often.

Family Life

Males compete for mates by engaging in carefully choreographed wrestling matches. The biggest and strongest Gila monster wins. Females dig holes where they lay a clutch (group) of large, leathery, oval-shaped eggs. She then covers them up so the sun’s heat can incubate them. Approximately four months later, the baby Gila monsters break out of their egg shells and crawl to the surface. They look like miniature adults but have more vivid coloring and are ready for life!

Conservation Status

The conservation status of the Gila Monster is classified as near threatened.
Near threatened graphic


  • The Gila monster is legally protected in all states where the reptile is found. Even though they are legally protected against hunting and being sold into the pet trade, habitat loss and degradation still pose large threats to the species.

Facts about Gila Monster

  • Class:
    Reptilia (reptiles)
  • Order:
    Squamata (scaled reptiles)
  • Family:
    Helodermatidae (heloderma)
  • Genus:
    Heloderma (venomous lizards)
  • Species:
    Heloderma suspectum (Gila Monster)
  • Life Span:
    8 years (wild) / 20 years (zoo)
  • Size:
    22 inches (56 cm) in total length
  • Weight:
    1.5 – 3 pounds (0.7 – 1.4 kg)

Fun Facts

  • This is one of only three venomous lizard species in the world. Their venom is at the back of their mouths, so they have to bite, hold, and chew their prey to give their venom time to work into a wound. However, the venom is used mainly for defense.
  • The Gila monster is legally protected in all states in which they are found.
  • A drug for the management of Type 2 diabetes is based on a protein from the Gila monster’s saliva. The drug is sometimes referred to as lizard spit.

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