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Gila Monsters & Beaded Lizards
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Helodermatidae
The family of Helodermatidae consists of one genus and two species. The two species are:
Gila Monster (Heloderma suspectum)
Beaded Lizard (Heloderma horridum)The distribution of the species' ranges are the southwestern U.S. and the western coast of Mexico. The U.S. species is Heloderma suspectum.
Heloderma suspectum inhabits arid to semi arid deserts. Its body is heavily built and cylindrical in shape. Its head is broad and flat with a blunt round nose. Its tail is thick and round. Its scales are very beadlike on its back, sides, head, and tail. It is black and "pinkish" in color.
Heloderma suspectum and Heloderma horridum are the only known venomous lizards. The venom glands are located at the posterior edge of the lower jaw. The venom reaches the teeth via a groove between the jaw and lip. The fangs are grooved in the front and, usually, also toward the back. Some upper jaw teeth also have grooves. The teeth are located deep in the gums. The gums are pushed back during a bite. This enables the teeth to penetrate 9-10mm deep into the target. The lizards must chew as they bite in order to inject the venom. The venom affects mainly the central nervous system. The venom can paralyze the respiratory system and, in this way, be lethal.
Gila Monsters and Beaded Lizards are nocturnal ground dwellers . They are active for only a short period of time during the year (the breeding season in spring & the rainy season in July and August). Most of the time, the lizards are resting in their burrows. They can use fat stored in their tails as sustenance.
In the wild, these lizards escape the worst of the desert heat by remaining in their burrows during the day. At dusk and part of the night they may be seen in bushy areas or crossing highways. As they crawl, they constantly flick out their forked tongue to pick up scents. The lizard will transmit the scents with its tongue to paired orifices in the roof of its mouth. The scents are used to identify food.
Gravid females deposit their eggs in mid-summer. Clutch sizes vary from 3 to 13 eggs. The young hatch after a 30 day incubation period. Hatchlings measure 14-20cm long. Some females have been known to lay several clutches a year.
Gila Monsters and Beaded Lizards adjust well to captivity. In captivity, these large lizards live for many years. They can be fed raw eggs and raw meat. Vitamin supplements should also be be included. (In the wild, these lizards eat small mammals and the eggs of birds and reptiles.) The vivarium should have a deep substrate in which to burrow. Day temperatures can vary from 80 to 92 degrees F. The basking area should be 100 to 103 degrees F. The night time temperature should be 68 to 73 degrees F. A large water bowl must be available for soaking and drinking. (The soaking behavior is known only to occur in captivity). Captive animals that are kept indoors soon abandon the inclination to defend themselves by biting. They settle down to a calm apathetic lifestyle. They often show no nervous reactions to humans. Although the captive Gila Monsters and Beaded Lizards are apparently docile, extreme caution should be taken when handling them.
Source: Dexter, Matt "Gila Monsters and Beaded Lizards Helodermatidae ." Newsletter of the Great Lakes Herpetological Society, June,1993.
