Gila Monster Facts

Scientific Name: Heloderma suspectum

Gila monster
Gila monster, overhead view.

Tim Flach / Getty Images

Gila monsters are part of class Reptilia and live mainly in the southwestern United States and northern Mexico. Their scientific name, Heloderma suspectum, is derived from the Greek words meaning stud (helo) and skin (derma). This name refers to their studded skin.

Fast Facts: Gila Monster

  • Scientific Name: Heloderma suspectum
  • Common Names: Gila monster
  • Order: Squamata
  • Basic Animal Group: Reptile
  • Distinguishing Characteristics: Heavy bodied lizard with a short tail and orange or pink spots on black skin.
  • Size: Up to 22 inches
  • Weight: 1.5 - 5 pounds
  • Life Span: Up to 20 years
  • Diet: Small birds, eggs, frogs, insects, lizards
  • Habitat: Deserts, Grasslands, Shrubland
  • Conservation Status: Near Threatened
  • Fun Fact: The Gila monster is named for the Gila river in Arizona.

Description

Gila monsters have venomous glands located in their lower jaw. Their large heads allow them to have strong bites that let their venom in the grooves of their teeth sink into the victim. They walk high on their legs to keep their tails clear of the ground and swing their tail back and forth to maintain balance.

These reptiles hunt during the spring and hide in burrows during the cold months, using fat stores in their tail to sustain them until spring time. They live up to 20 years in the wild, can grow up to 22 inches, and weigh between 1.5 and 5 pounds.

Habitat and Distribution

Gila monsters live in southwestern United States and northern Mexico, in habitats such as deserts, grasslands, and shrubland. They live at ground level and usually make their homes in burrows in rocky areas.

Diet and Behavior

Gila Monster
Gila monster eating a mouse. John Cancalosi/Photolibrary/Getty Images

Gila monsters are carnivores, and their diet consists primarily of small birds and eggs. They also eat lizards, frogs, insects, and small mammals.

In situations of extreme temperatures during the day, gila monsters may be more active at night. Because they are relatively slow—reaching only about 1.5 miles per hour—they rely on stealth to catch their prey and also search cacti for eggs in bird nests. Additionally, gila monsters can not see well, so they rely on their strong sense of smell and taste to track their prey. They flick their tongues to pick up scents in the air. These creatures can eat up to 1/3 of their body weight and can store fat in their tails. This reduces the amount of time gila monsters have to spend foraging for food.

Gila Monster Bite

Gila monsters have powerful jaws that allow them to bite and hold on to their victim for up to 10 minutes. They store venom in the grooves of their teeth in their lower jaw. Most of its food can be consumed by swallowing it entirely or with one quick bite. For larger prey, like small mammals, gila monster venom seeps into the body of the bitten animal and attacks its nervous system. A gila monster bite can be very painful to humans but isn't typically fatal.

Reproduction and Offspring

Gila Monster
Gila monster hatching from an egg.  C. Allan Morgan/Photolibrary/Getty Images

Gila monsters reach the age of maturity between 3-5 years. Breeding season is in early summer, when males compete by participating in wrestling matches. The female digs a hole and lightly covers her 2-12 eggs that weigh 1.4 ounces and span 2.5 by 1.2 inches on average. Roughly 4 months later, the eggs hatch and gila monsters of sizes averaging 6.3 inches emerge. They look like miniature adults with more vibrant colors and are on their own at birth.

These young will grow to become diurnal creatures that spend the majority of their lives underground with a burst of activity during the spring, which is spent hunting for food. Three to four large meals will be all the food it needs to survive the winter. They are mostly solitary animals, but gather in small communities during mating season.

Conservation Status

Gila monsters are designated as Near Threatened by the International Union for Conservation of Nature (IUCN).

While the total number of gila monsters is unknown, their population has been found to be decreasing in the United States and Mexico at an unknown rate. The biggest threat to gila monsters is humans, as the animals are hunted as prized possessions and killed by household pets. They are also illegally collected as pets.

Gila Monsters and Humans

Notably, a protein component of gila monsters’ venom called Exendin-4 is used in a drug to manage Type II diabetes. The protein has a homeostatic effect by regulating glucose levels in the body. Researchers have found this drug to help manage Type II diabetes by boosting insulin secretion and restoring insulin response. Researchers are currently looking into whether this protein can be used to treat memory disorders like Alzheimer’s disease.

Sources

  • C., Triplitt, and Chiquette E. "Exenatide: From The Gila Monster To The Pharmacy.". NCBI, 2006, https://www.ncbi.nlm.nih.gov/pubmed/16529340.
  • "Foothills Palo Verde Fact Sheet". Arizona-Sonora Desert Museum, 2008, https://www.desertmuseum.org/kids/oz/long-fact-sheets/Gila%20Monster.php.
  • "Gila Monster". The IUCN Red List Of Threatened Species, 2007, https://www.iucnredlist.org/species/9865/13022716#population.
  • "Gila Monster". Smithsonian's National Zoo & Conservation Biology Institute, 2019, https://nationalzoo.si.edu/animals/gila-monster.
  • "Gila Monster Lizard". Fws.Gov, 2019, https://www.fws.gov/mountain-prairie/es/gilaMonster.php.
  • "Gila Monster | San Diego Zoo Animals & Plants". San Diego Zoo, 2019, https://animals.sandiegozoo.org/animals/gila-monster. Accessed 1 June 2019.
  • Zug, George R. "Gila Monster | Description, Habitat, & Facts". Encyclopedia Britannica, 2019, https://www.britannica.com/animal/Gila-monster.