Gila Monster - biology.

Gila Monster - biology. Gila Monster, common name for the largest lizard in the United States, the only poisonous lizard in the United States and one of the only two poisonous lizards known in the world that are specialized to give a poisonous bite. It is found in desert areas of Arizona, Nevada, Utah, and New Mexico and in northwestern Mexico. The Gila monster is heavily built and moves slowly on four short legs, dragging a thick, short, blunt tail. Fat is stored in the tail, and the lizard can live for months on this reserve. The adult lizard is between 46 and 61 cm (18 and 24 in) in length with an often strikingly colored body--black with numerous beads, or tubercles, of pink, orange, yellow, or white; the black head is marbled with pink. The tongue is forked, broad, and flat. Gila monsters eat mostly small rodents, juvenile birds, and bird and reptile eggs. In captivity, the lizards have shown a fondness for chicken eggs or dead white mice. Gila-monster eggs are leathery-shelled and about the size of hen eggs. Females lay about a dozen eggs in a wide hole in moist sand, cover them, and then abandon them. The young hatch in about 10 months. Gila monsters bite and then hang on strongly. The poison, used mainly as a defense, is secreted by glands in the lower jaw and flows out along grooves on the teeth of the lower and upper jaws. Although the bite can be a threat to human beings, the poisoning of humans by Gila monsters is rare and usually the result of careless handling. The beaded lizard, a closely related species found in Mexico and Guatemala, has a similar kind of poisonous bite. Recent studies show that a number of types of lizards also have venom-secreting glands in their mouths, but lack the specialized teeth and large quantities of poison that the Gila monster and the beaded lizard have. In the United States, the Gila monster is protected by federal and state laws. Scientific classification: The Gila monster belongs to the family Helodermatidae. It is classified as Heloderma suspectum. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.