Species Fact Profile: Gila Monster (Heloderma suspectum)

Gila Monster

Heloderma suspectum (Cope, 1869)

Range: Southwestern United States, Northwestern Mexico
Habitat: Desert
Diet: Small Mammals, Birds, Lizards, Eggs
Social Grouping: Solitary
Reproduction: Mate in the spring.  Female lays up to 12 eggs in in underground cavity in July or August.  Eggs incubate approximately 10 months and emerge in May
Lifespan: 20-30 Years (Captivity)
Conservation Status: IUCN Near Threatened

• The largest lizard in the United States: a stout-bodied lizard, body length up to 56 centimeters.  Generally weight 350-700 grams, but some specimens have weighed over 2 kilograms. Limbs and tails are short and thick, feet end in heavy claws
• Bony, round scales resemble small beads, black with patterns of yellow, pink, or orange
• Able to consume enormous meals, sometimes 50% of their own body weight.  May only need to feed a few times per year.  Fat can be stored in the tail
• Spend much of their time underground, primarily active in the spring
• Prey is detected by smell; like snakes (and unlike many lizards), the tongue is used for olfaction
• Along with the closely related beaded lizard (Heloderma horridum), the Gila monster is often considered the only venomous lizard on earth (some authorities consider the Komodo dragon and other monitor lizards to be venomous as well)
• Venom is produced in modified salivary glands in the lower jaw, is transfered into the victim as the lizard chews, running through grooves on the teeth
• Rarely envenomate their prey, instead using venom for defense.  Bites are extremely painful to humans, but rarely life-threatening
• Proteins from Gila monster venom are being used in medication to treat diabetes
• Two subspecies which can be identified by their patterns: the reticulated Gila monster (H. s. suspectum), which has a net-like pattern, and the banded Gila monster (H. s. cinctum)
• Named after the Gila River; the Latin name translates to "Suspicious nail-skin", referring to both the nail-like scales on the skin and the fact that its describer, Edward Drinker Cope, suspected that the species was venomous.
• Legally protected across its range, but sometimes killed out of fear, also some illegal collection for the pet trade