Beaded Lizard

(Heloderma horridum)




Facts about this animal

Beaded lizards grow to about 76 cm in length and weigh 1.4 to 2 kilograms. Males are slightly larger, growing to 90 cm and weighing up to 4 kilograms. They have a cylindrical body with a long, thick tail. The head is wide and flat, and the legs are short and strong. The colour is dark-brown to black with many pink, yellow or orange spots. The skin consists of several tiny beads called ostioderms. Each bead contains a tiny piece of bone that gives them almost an armor plated skin. The forked tongue is serpentine in nature and flicks in and out to smell, much like a snake. Sexual maturity is reached at two and a half to three years. The breeding season is in February and March and copulation lasts 30-60 minutes. About 2 months later, females lay 3-13 elongated eggs and bury them at a depth of about 12.5cm. The incubation period of the eggs is around 165 to 215 days. Newly hatched lizards are usually five to six inches long and weigh around 40 grams. In the wild they are active from April to mid-November. They spend only about an hour per day above the ground, usually at dusk or at night, hiding the rest of the day in self-dug or pre-existing burrows. The natural diet consists of small mammals, birds, lizards, frogs, insects, and eggs of birds and reptiles. The lifespan is said to be around thirty years but they probably even get older.

Did you know?
that the lizards of the genus Heloderma were thought until recently to be the only venomous lizards in the world; in fact to be the only poisonous reptiles besides the poisonous snakes. However research at the University of Melbourne, Australia and Pennsylvania State University has revealed that in fact many lizards in the iguanian and monitor families have venom-producing glands. In the two Heloderma species the toxin is produced in modified glands in the lower lips and is then transferred to the teeth of the lower mandible. At the base of each tooth is a grooved pit for venom delivery. The upper jaw contains no poisonous glands. Since these animals are not able to release the toxin in a high amount and at once in one bite, they lock jaws and hold fast. Through chewing movements they knead the toxin into the wound. Therefore the bite is extremely painful. It can be potentially fatal, but this is only in extremely rare cases. Before biting they emit a warning with a hissing sound. In fact they use the venom primarily as a defensive weapon (coyotes, raptors, humans). The latin name consists of the word Heloderma, meaning "studded skin", and the word horridum, meaning "horrible" (= "horrible studded skin lizard").


Name (Scientific) Heloderma horridum
Name (English) Beaded Lizard
Name (French) Héloderme granuleux
Name (German) Skorpionkrustenechse
Name (Spanish) Lagarto de Cuentas
CITES Status Appendix II; the subspecies Heloderma horridum charlesbogerti is on Apendix I
CMS Status Not listed



Photo Copyright by
Piccolo Namek



Range Mexico, Guatemala
Habitat Primarily tropicial deciduous forest and dry thorn scrub forest, but they can also be found in pine-oak forest and tropical scrubland, with elevations from sea level to 1500 meters. However they do not seem to be present in disturbed areas.
Wild population It is threatened by various forms of deforestation and by human persecution. It appears to be an uncommon species (Red List IUCN 2011)
Zoo population 217 reported to ISIS (2007)

In the Zoo

Beaded Lizard


How this animal should be transported

For air transport, Container Note 41 of the IATA Live Animals Regulations should be followed.


Find this animal on ZooLex


Photo Copyright by
Trisha Shears

Why do zoos keep this animal

Heloderma horridum is a vulnerable species. In 1990, an International Studbook was initiated, but this was discontinued in 1998 and coordinated ex- situ breeding efforts are since taking place at the regional level.

As Heloderma is the best-known venomous lizard genus, keeping beaded lizards is also of educational interest.