Banded Gila Monster

 Banded Gila Monster

Scientific Name: Heloderma suspectum
Family: helodermatidae
Classification: Reptile - lizard
Size: 9-14 inches (22-35 cm) plus the tail
Life Span: May live 20 to 30 years 



The gila monster is distinctive among other reptiles. It is a large, heavy-bodied lizard with a massive head, a short, swollen sausage-shaped tail and a mottled pattern of black and pink, orange, or yellow beadlike scales. Its dark forked tongue flicks out in snake-like fashion. The legs are short and appear set too far apart to support the lengthy body. The feet have strong curved claws used for digging.


The gila monster is found in most habitats throughout its range. It is common in areas with saguaro cactus and along washes at elevations from near sea level to 4,100 feet. Its range is limited to regions that receive several inches of rain during the summer months and have mild winters and hot summers.


The gila monster is primarily a desert species. It occurs in extreme southwestern utah, the southern tip of nevada, southwestern new mexico, arizona, and sonora.

Natural History:

The gila monster and the closely related mexican beaded lizard are the world’s only known venomous lizards. They are also the largest lizards in north america.

Venom is produced in glands in the lower jaw. From 41 to 45 sharp teeth line the upper and lower jaws. Gila monsters lack hollow fangs like those found in rattlesnakes. Instead, their front teeth have grooves which facilitate the movement of venom through their saliva as the lizard chews. The venom is used in subduing some prey and also as a defense against some predators such as owls, kit foxes, coyotes and rattlesnakes. A bite from a gila monster is powerful and painful but rarely fatal to humans.

The food-acquiring methods of the gila monster are a deadly combination of powerful digging limbs and powerful jaws combined with especially keen senses of smell, hearing, and the sensing of ground vibrations. These soil diggers are opportunists that occasionally eat birds and lizards, and the eggs of birds and reptiles. They are highly successful carnivores that swallow their prey whole.

The gila monster’s tail is a good indicator of its physical condition. A plump, well-rounded tail is the sign of a well-fed, healthy animal. A skinny, triangular-shaped tail indicates the gila monster may be starving and dehydrated. Serving as a fat storage-locker, the gila monster’s tail is not detachable as is the tail of many other species of lizards. Gila monsters can survive several years on the stored fat in their tails.

The growth rate of the wild adult gila monster is slow and averages from 1/10th-1/5th of an inch a year, depending on the animal’s size and condition. Young gila monsters grow at a faster rate than the adults. Hatchlings may grow two inches or more a year in the first three years or so.

Gila monsters may be observed both during the day and at night. They are most active in april and may when their chances of securing food are best, and at night during the summer rainy season. In november they enter hibernation are not seen on the surface again until march.

Food Habits:

Gila monsters eat small mammals; eggs, chiefly of ground-nesting birds (quail and mourning dove) and reptiles, lizards, insects and carrion (dead animals).


Gila monsters reach sexually maturity in four to five years at which time they are 14-16 inches in length and weigh 1-1½ pounds. Females lay a clutch of 1-8 eggs (possibly to around a dozen) july to august. The hatchlings are about 6-6½ inches and weigh just over one ounce.


State protected but not listed as threatened and endangered. Utah and arizona also classify the gila monster as protected.

Reason for Status:

Reasons for status include: habitat loss due to urbanization and some agricultural uses; illegal collection; restricted range in nevada; and limited knowledge and information. Cites (convention on international trade in endangered species refers to the gila monster as being “a species not currently threatened, but may become so unless trade is regulated…” occasionally it is killed out of fear since it is venomous.

Management &Conservation:

Currently collection (commercial or personal) of gila monsters is prohibited in nevada. Nevada department of wildlife supports on-going gila monster research projects conducted by the university of nevada reno and other individuals and agencies.

Fun Facts:

  • The gila monster is one of the most misunderstood, maligned, molested, and mythologized animals in the world.
  • Their scientific name (helo, “warty”; derma “skin”) describes the beaded or warty look of their bright-colored skin—pink, orange or yellow with black banding.
  • The gila monster is the largest lizard or “saurian” native to the u.s. (alligators are not considered lizards but crocodilians.)
  • Gila monsters are the slowest lizards.
  • Gila monsters are the only lizards, living or extinct, to possess grooved teeth and venom glands.
  • Occasionally the brick-red and black male chuckwalla is misidentified as a gila monster, and people commonly mistake banded geckos for baby gila monsters.
  • Gila monsters are weak but persistent swimmers and take to the water without hesitation.
  • More than 99% of a gila monster’s life is spent underground and out of sight.
  • A gila monster is most likely to be seen in the month of may than any other time of the year.