At a length of up to two feet (0.6 meters) and a maximum weight exceeding five pounds (2.3 kilograms), the venomous Gila monster (pronounced HEE-luh) is one of the largest lizards. Easily identified by their black bodies marked with dramatic patterns of pink, orange, or yellow, Gilas are found in the Mojave, Sonoran, and Chihuahuan deserts of the southwestern U.S. and northwestern Mexico. They take their name from Arizona’s Gila River basin, where they were first discovered. The Gila monster is one of only a handful of venomous lizards in the world. Others include the similar-looking Mexican beaded lizards, as well as iguanas and monitor lizards. Its venom is a fairly mild neurotoxin. And though a Gila bite is extremely painful, none has resulted in a reported human death. Unlike snakes, which inject venom, Gilas latch onto victims and chew to allow neurotoxins to move through grooves in their teeth and into the open wound. Gila’s are lethargic creatures that feed primarily on eggs raided from nests and newborn mammals. They may spend more than 95 percent of their lives in underground burrows, emerging only to feed and occasionally to bask in the desert sun. They can store fat in their oversized tails and are able to go months between meals.
The range of the Gila monster is primarily in Arizona and Mexico, the extreme southeastern corner of California, the southern tip of Nevada, and the southwestern corners of Utah and New Mexico. It is named for the Gila River in whose drainage it is a common resident. Gila monsters are desert dwellers, living near washes and arroyos and in semiarid rocky regions of desert scrub or grasslands. Gila monsters also seem to prefer rocky foothills and avoid open flats and agricultural areas. They can live in elevations up to 5,000 feet (1,500 m).