Monday, May 23, 2011
Species of the Day: Beaded Lizard
Scientific Name: Heloderma horridum
Adult Size: The various subspecies usually grow between 24 to 30 inches long but occasionally reach 4 feet in length
Range: Western coast of Mexico from southern Sonora, south to an isolated population in central Guatemala
Habitat: Mesic forested hillsides with pronounced wet and dry seasons
The beaded lizard is a species of venomous lizard found principally in Mexico and southern Guatemala. It is one of two species of lizards, along with the Gila Monster, that has developed an overt venom delivery system. The beaded lizard is larger than the Gila Monster but has duller coloration; black with yellowish bands of differing width depending on the subspecies. A specialized predator that feeds primarily on eggs, nesting animals and their young, the primary use of its venom is still a source of debate among scientists. This venom, however, has been found to contain several enzymes useful for manufacturing drugs in the treatment of diabetes, and the research on the pharmacological use of its venom is ongoing. Threatened throughout its range by illegal poaching for the pet trade and habitat loss, the beaded lizard is a CITES protected animal. The Motagua Valley subspecies (H.h. charlesborgeti) is one of the rarest lizards in the world, with a wild population of fewer than 200 animals. The beaded lizard is also surrounded my myth and superstition in much of its native range. It is incorrectly believed to be more venomous than a rattlesnake, that it can cause lightning strikes with its tail or make a pregnant woman miscarry my simply looking at it, and as a result the local people will kill them on sight.
As captive animals, their sometimes sour tempers and venom commands respect and they should not be handled casually. The beaded lizards venom is a weak hemotoxin and although deaths in humans are rare, it can cause respiratory failure. Almost all documented bites (8 in the last 100 years), resulted from people harassing the animals by prodding them with a finger or foot. As stated before the their are many pharmacological properties to this venom relating to diabetes, Alzheimer's Disease and even HIV/AIDS. One study done in 1996 revealed that a certain hormone in the saliva binds to cell receptors from breast cancers cells and my stop lung cancer. Long-term captive lizards may become sluggish and seemingly tame, but they should never be trusted to not deliver a lightning fast, bulldog-like bite. Beaded lizards are most active when temperatures are in the 80's F, regardless of what time of the day it is, so a temperature gradient in this range, with a basking bulb at one end of the enclosure works best for these lizards. Now these lizards are semi-arboreal and at the same time prolific diggers, and so can be hard on their environment and need a strong, solidly built enclosure with sturdy climbing branches and a good burrowing substrate mix of untreated soil, gravel and mulch. A heavy ceramic bowl will serve as a good water bowl and a hide box constructed of sturdy wood will complete the set-up. Captive beaded lizards will eat frozen chicks and rodents along with eggs.