Beaded lizards are a species of venomous lizard found mainly in tropical and scrub forests in the Southwestern United States, Northern and Southwestern Mexico, and Northern Guatemala. Adults are 13 to 18 inches in length, and they weigh between five and six pounds, with the male being slightly larger than the female. They have black bumpy scales that give it a beaded appearance, while the belly has soft scales that are beaded as well. The tail and the neck are covered in stripes and spots white to yellow in color. The tail is the longest part of the lizard at about 50% of its total length. This is where most of the fat is stored and will give the species energy in times of scarce food. They have a forked black tongue that they use to smell, much like a snake does. Beaded lizards become sexually mature around eight years of age and breed between February and March. After two months, females lay between three and 13 eggs and bury them about 12 centimeters into the ground to incubate for six months. This is all the parental care that the lengthened eggs receive and the juveniles are about five or six inches when they hatch. Having very few natural enemies (only humans, coyotes, and some raptors), the hatchlings are given a greater chance of survival. The lifespan of these lizards is over 30 years.
This species is nocturnal and resides in burrows during most of the day. As an adult, this species is carnivorous, feeding on small mammals, birds, lizards, frogs, insects, and eggs. This is one of two lizards (along with the Gila monster) that were thought to be the only venomous reptiles in the world, apart from venomous snakes. However, recent research has discovered that many lizards in the iguana and monitor families have venom-producing glands. In the two Heloderma species (the Beaded lizard and Gila monster), the toxin is produced in modified glands in the lower lips. From there, it is transferred to the teeth of the lower jaw. The toxins can’t be produced in large amounts, so they use chewing movements to rub the toxin into the wound. They use this tactic only defensively and emit a warning with a hissing sound first. Humans are the biggest threat to the Beaded lizard due to habitat loss and fear of their venom, giving them the classification of Vulnerable by the IUCN.