Gila Monster (Heloderma suspectum)
Order: Squamata, Family: Helodermatidae
The Gila monster is the largest lizard native to the United States. It is one of only two types of poisonous lizard.
It is large and stout, with short legs and strong claws, and a short, thick sausage-shaped tail. Its head is large, and it has wide jaws containing sharp teeth and venom glands in the lower jaw.
Gilas measure 12 to 24 inches long and weigh 2 to 3 pounds.
Its scales are beaded pink, yellow, orange and black. It has a black face and feet.
II. GEOGRAPHICAL RANGE AND HABITAT:
- The Gila monster is the largest lizard native to the United States. It is one of only two types of poisonous lizard.
- It is large and stout, with short legs and strong claws, and a short, thick sausage-shaped tail. Its head is large, and it has wide jaws containing sharp teeth and venom glands in the lower jaw.
- Gilas measure 12 to 24 inches long and weigh 2 to 3 pounds.
- Its scales are beaded pink, yellow, orange and black. It has a black face and feet.
- The Gila's range covers the southwestern United States to northern Mexico.
- Gilas live in deserts and arid areas of gravelly and sandy soils with shrubs.
- They hide under rocks, in the burrows of other animals and in holes they dig themselves.
IV. LIFE CYCLE/SOCIAL STRUCTURE:
- Carnivores, Gilas eat mainly nesting rodents, but also birds, lizards, insects, scorpions, and occasionally bird and reptile eggs.
V. SPECIAL NOTES/ADAPTATIONS:
- Gilas are slow-moving, but can lunge quickly. Solitary animals, they're active mainly at night.
- When not foraging, the Gila spends over 98 percent of its time underground or at its den entrance.
- The Gila is active during the day from early March to mid May, and then changes to nighttime activity when the rainy season comes. During the winter, it stays in its burrow.
- Gilas court and mate from late April to early June; a female will lay three to 12 eggs sometime between mid-July and mid-August. She'll bury the leathery eggs in an open place exposed to sun, usually near a stream or dry wash; young are 3 1/2-4 1/2 inches long and reach adult size in one to three years.
- Gilas live for approximately 20 years.
VII. POPULATION STATUS:
- During warm weather, the Gila feeds at night; in the winter, it survives off fat stored in its tail and abdomen.
- It methodically searches for food above and below ground. A strong digger and good climber, the Gila bites and clamps down on prey with a tenacious hold. Venom is chewed in through grooves in rear teeth of lower jaw.
- It uses taste and smell to track prey by frequently flicking forked tongue to taste ground.
- The Gila's venom glands are located in its lower jaw, and its teeth are grooved, but not hollow. Venom empties into the mouth through several ducts that open between the teeth and lips.
VIII. MORE FACTS ABOUT GILA MONSTERS:
- Overgrazing, truck farming and cotton planting have destroyed much of the Gila's habitat.
- The Gila's survival is not presently threatened, but may become so unless trade is regulated. The Gila may be moved to the endangered category in the near future if conditions do not improve. It is protected by Arizona state law.
- The family Helodermatidae consists of only two species: Heloderma suspectum (Gila monster) and Heloderma horridum (Mexican beaded lizard).
- These two species are the only known venomous lizards. Their bite is painful, but seldom fatal to man.
- A swollen tail indicates that a Gila monster is well fed.
- It is named for the Gila River Basin, located in the southwestern United States.
- Although a Gila monster's bite can overpower predators and prey, it is rarely fatal to humans.
- On April 3, 1952, the Gila monster became the first reptile to be protected in Arizona and the first venomous reptile to be protected in the United States. It is protected throughout its range in both the United States and in Mexico.