Gila monster



The Gila monster (pronounced (HEE-luh) is a large lizard living in the south-western United States and north-western Mexico. They inhabit dry deserts and rocky mountain foothills.  These animals are one of the most recognizable lizards in North America. They can easily be recognized by their black bodies with pink, yellow, orange, or even white markings on their back. As with many desert-living lizards, gila monsters have a tail that stores excess fat. If prey or water is scarce they can use these fat reserves to survive until they can find food. There are two different subspecies of gila monsters that can be differentiated by their markings. These two subspecies are the reticulated gila monster and the banded gila monster. Reticulated gila monsters, like the one above, have splotches of the orange color all over their bocy that are mostly connected. Banded gila monsters, like the one below, have stripes of those markings. A group of gila monsters is called a lounge.



Gila monsters are one of only two venomous lizard species in the world! The other species is the Mexican beaded lizard, which lives in some of the same area as the gila monster. Although their bite is extremely painful, gila monsters have never been known to kill a human with their venom. They use their venom mainly to protect themselves from predators, and this venom attacks the nervous system, shutting it down. Rarely if ever does a gila monster use its venom to kill prey. When a gila monster bites, it latches on and chews in the venom unlike snakes which just give a quick bite. The venom of these monsters can actually be beneficial to humans sometimes. A man-made version of one of the proteins in the gila monster’s venom is used to treat diabetes.

In culture

Other than snakes, gila monsters probably are one of the most feared reptiles. In local folklore, it has been described as frightful and repulsive. They have been described as spitting venom, being able to jump several feet into the air, and killing people with gusts of poisonous breath. None of these myths are true, however.


Gila monsters can grow to be about 24 inches (60 cm) in length, making them the largest lizards in North America. Despite being so large for a lizard, they do not weigh a whole lot at only five pounds (2.2 kg).


Gila monsters, as with most lizards, are carnivores. They do not have good eyesight, and find their prey by taste and smell. Like snakes, these animals flick out their tongues to collect scent particles in the air. Although they can run about 15 miles per hour (24 km/h), this is not very fast in the animal world, and they must sneak up on their food in order to catch it successfully. They are also very lethargic and only run when they have to. Typically, though, they do not eat food that will be extremely hard to capture. Their diet mainly consists of young mammals and eggs that they raid from nests. In the zoo they are fed two mice each twice a month.

Threats and status

The IUCN Redlist classifies gila monsters as “Near Threatened.” Some of the main predators of this animal are domestic dogs and cats, birds of prey, and coyotes. A lot of the land these animals live in is being converted to land suitable for agriculture, and this makes their range continually shrink. Although it is illegal, some of these animals are collected for the pet trade. Given the gila monster’s venom, though, I do not think I would want a pet gila monster even if it was legal. In 1952, Arizona passed a law protecting gila monsters. This was the first time venomous reptiles had received such legal protection. About 300 known gila monsters live in captivity in the United States, and it is hoped that conservation methods, including captive breeding, will help these animals survive even if much of their habitat is destroyed.


Gila monsters spend most of their time, up to ninety-five percent of it in fact, in their burrows. During the day, they spend their time underground in order to avoid the morning and afternoon heat. They also hibernate in the winter, and the majority of their activity takes place from April to June. While hibernating, they survive off of the fat stored in their tails.

Reproduction and young

April through June is therefore the time gila monsters choose to mate. Males will wrestle each other to decide who is dominant. In between late June and August, the female lays a clutch of from two to fifteen eggs. They lay the eggs in depressions they dig in the ground. These eggs are incubated by the ground throughout the winter and hatch the following spring. After hatching, the young are about six inches (15 cm) and are exact replicas of their parents. In the wild, these animals can live for up to thirty years, and they have been reported living up to thirty-five years in the wild.

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Photo credits:

  • Reticulated gila monster – Josh Olander
  • Banded gila monster – H. van der Ploeg
  • Mystery animal – Cburnett
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