Reticulate Gila Monster

Heloderma suspectum suspectum

Venomous

Considered harmful to humans.

Description

A large heavy bodied lizard with a distinctive large wide head and fat "sausage-like" tail. The legs are short and stout and the feet & toes somewhat resemble a human hand with long sharp claws. The dorsal skin is covered with hard round bead-like osteoderms. Adults reach an average total length of 48-55 cm (19-22 in), at times reaching a total length of 61 cm (24 in)[1].

This subspecies is adorned with a reticulated pattern of black and pink, rose or orange colored blotches forming irregular and incomplete bands around the body and tail. The top of the head is also adorned with coloration but the face and top of the snout are nearly always black. The eyes and tongue are both black in color.

Similar Species

Quick ID Notes

Habitat

Sonoran Desert, elevation- Sea level to 1,550 m (5,100 ft.)[2]. May be found in a variety of desert habitats including, desert scrub, semi-desert grasslands and woodland habitats of desert mountain foothills. The habitat type known to naturalists as Arizona Upland is the most frequented habitat of the Reticulate Gila Monster. This habitat is dominated by Creosote, Paloverde and Saguaro as well as a diversity of other shrubs, trees and cacti, and receives an average of 279 mm (11 in) of rainfall per year.[3]

Activity

Gila Monsters spend the great majority of their time in shelters, yet they are foragers who will cover as much as one km/day in search of a meal or a mate[2]. They are diurnal as well as nocturnal foragers. Their preferred habitat is rocky slopes with sufficient boulders, rock outcroppings, crevices, rodents and rodent burrows. Moisture is also an important element of the preferred environment as Gila Monsters are susceptible to dehydration due to evaporative water loss. Like many other desert animals, they store water in the urinary bladder that can be later absorbed to offset dehydration[2].

Gilas normally emerge in January and February when they will usually not venture too far from their wintering dens. The peak time of surface activity traditionally occurs in May. In the hotter months of summer, the lizards will become more nocturnal in nature and can be found wandering in the desert late at night.

Records of Reticulate Gilas surviving in the wild in excess of 20 years is not uncommon. There are records of captive specimens in Tucson, Arizona, exceeding 30 years of age[3]. Gila Monsters hold the distinction of being the first venomous reptiles to receive legal protection in North America, and are among the most studied and recognized reptiles on the continent.

Reproduction

Oviparous. Mating takes place in late April thru early June. Eggs are deposited six to eight weeks after fertilization. Females will deposit 2 to 12 eggs measuring 24-32 mm (1-1.25 in) wide by 58-64 mm (2.25-2.5 in) long. The young hatch nearly a full year after mating and fertilization.

Diet

A forager feeding mainly on the contents of ground nesting animals. Bird eggs, reptile eggs, young cottontail rabbits, wood rats and other rodents make up the bulk of the diet. Gila Monsters have also been observed scavenging on road killed mammals such as mice and rabbits.

Range

The Reticulate Gila Monster Heloderma s. suspectum is found in Southern Arizona, southwestern New Mexico and most all of Sonora, Mexico.

Meaning of Scientific Name

Heloderma
Helos (Greek) nail or stud + Derma (Greek) skin[4]
suspectum
(Latin) mistrust or suspect.[4]

The species name suspectum was given to this animal for its venomous nature which was only suspected and not proven at the time of the naming.

Conservation Status

Gila Monsters are protected under the state laws of all of the U. S. and Mexican states in which they naturally occur.

Taxonomic Notes

There are two subspecies of Heloderma suspectum recognized: the Reticulate Gila Monster, Heloderma suspectum suspectum, and the Banded Gila Monster, Heloderma suspectum cinctum.

References

  1. Ditmars, Raymond L. The Reptiles of North America. Doubleday & Company Inc. 1936
  2. Jones, Lawerence L. C. & Lovich, Robert E. Field Lizards of the American Southwest, A photographic Field Guide, Rio Nuevo Publishers, Tucson Arizona, 2009
  3. Beck, Daniel D. Biology of Gila Monsters and Beaded Lizards. University of California Press, 2005
  4. Beltz, Ellin. Scientific and Common Names of the Reptiles and Amphibians of North America - Explained, http://ebeltz.net/herps/etymain.html, 2006

Classification

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