Chuckwalla Western Fence Lizard
© AMNH / Denis Finnin
These lizards like wide-open spaces. The big one basks on large boulders, and the small one scurries underfoot all over the Southwest.
When Chuckwallas are threatened, they wedge themselves in rock crevices to avoid being eaten. They also expand like balloons. Many lizards inflate themselves to look bigger and more menacing--in the Chuckwalla's case, it also makes the fit tighter.
These fine scales help the Chuckwalla slip into cracks and crevices of desert boulders. Once there, the pressure of its inflated body against the rock makes it hard to dislodge.
Sharp claws help anchor the Chuckwalla in its rocky hideaway and tighten its grip on rocky surfaces.
© AMNH / Denis Finnin
Western Fence Lizard
The color of this lizard has earned it the nickname "blue belly." Bright body colors are one way lizards communicate.
The Fence Lizard's scales are always keeled, or ridged; ridges may provide stiffness and strength. Lizards with keeled scales look rough; lizards with flat scales look shiny.
You can't see it, but something about these lizards helps prevent a serious human illness called Lyme disease. When the ticks that transmit the disease feed on fence lizards, a protein in the lizard's blood kills the Lyme bacteria. If that tick then bites a human, the human won't get sick.
Meet the Families
A Fence Lizard or a relative--Phrynosomatidae, including about 130 species in all--can be found in nearly every habitat in North and Central America: from cliff faces to cloud forest to sand dunes. Chuckwallas and their close relatives-Iguanidae, including around 40 species in all--also occupy a wide range of habitats.
© Wendy Hodges/University of Texas Permian Basin
Mexican horned lizard
Mexican Horned LizardPhrynosoma asio
When threatened, these lizards squirt blood from vessels in the corners of their eyes. Some predators are repulsed by the blood--perhaps more by its smell than its appearance.
© Jonathan Campbell/University of Texas Arlington
Mesquite LizardSceloporus grammicus
Freezing temperatures are common where this lizard lives, high on mountains in Mexico. Amazingly, the animals can tolerate freezing and thawing without ill effects.
© Tom Brennan/Arizona State University
Mojave Fringe-toed Lizard
Mojave Fringe-toed LizardUma scoparia
This animal lives on-and in-windblown dunes, diving beneath the sand for cover. Special valves on its nose keep the sand grains out. In some areas its habitat is threatened by humans in off-road vehicles.
Name: Chuckwalla; Sauromalus ater
Size: 28 to 46 centimeters (11 to 18 inches)
Range: Southwestern U.S. and Mexico
Diet: Fruits, leaves, buds and flowers
Name: Western Fence Lizard; Sceloporus occidentalis
Size: 13-15 centimeters (5-6 inches)
Range: Western U.S.