Black Iguana, Ctenosaura similis, image by Johan Seibols, taken in Mexico's Yucatan Peninsula

Iguanid Lizards (Iguana Family, the Iguanidae): These are the "typical lizards," such as the Black Iguana, Ctenosaura similis, shown above. Iguanid lizards are usually the most commonly encountered ones. They can be either arboreal or terrestrial. Typically but not always they feed on insects and other invertebrates. Most are egg-layers, and most are very visually oriented, communicating with one another with their colors and behavioral signals. Mates are courted, territories are defended, and during confrontations they often bob their heads, do body push-ups, and open their mouths at one another. Many species are intensely colored during mating season. Included in this large family are fence lizards, iguanas, horned lizards, chuckwallas and anoles.

Green Anole, Anolis carolinensis, image by Hillary Mesick of Mississippi

Anoles (Iguana Family, the Iguanidae, genus Anolis): common in the US Southeast, lots of fun to watch as they slowly stalk their prey of flies, beetles, moths, spiders and other such critters. Often Green Anoles (uh-NO-lehs) are known as chameleons because in just a few seconds they can change color between green and brown. Anoles lay only one egg every couple of weeks. They possess toe pads and brightly colored "throatfans" that fan out below their heads when they are displaying.

Coast Horned Lizard, Phrynosoma coronatum, image by Gary R. Zahm, courtesy of U.S. Fish and Wildlife Service Horned Lizards (Iguana Family, the Iguanidae, genus Phrynosoma): "horny-toads"; covered with short, blunt spines, found in the western U.S. and southward. At the right is a Coast Horned Lizard, Phrynosoma coronatum, distributed through most of western California, into Baja California, Mexico.

chuckwalla Chuckwalla (Iguana Family, the Iguanidae -- a single species, Sauromalus abesus): large, potbellied, with folds of skin around neck and shoulders; found in southeastern California, southern Nevada, Utah, western Arizona and adjacent Mexico. Active during the day (diurnal), it emerges in the morning and basks in sunlight until its body temperature reaches about 100º F (38º C), and then it begins searching for food. It is a  vegetarian, eating mainly leaves, buds, flowers and fruit.

Southern Alligator Lizard, Gerrhonotus multicarinatus; photo by Daniel Adams of California

Alligator Lizards (Anguid Lizard Family, the Anguidae): Not alligators (Alligators are in their own order, like the Turtle Order and the Lizard Order), these lizards at first glance are similar to fence lizards, who are members of the Iguana Family. However, this group is anatomically different from other lizards, especially with regard to the bonelike scales (osteoderms) covering its body. Also, its legs are relatively small, even absent in some species.This lizard's heavy body armor makes its body so stiff that it would be hard for the animals to breathe were it not for a flexible band of soft, granular scales along the side, shown in the inset at the upper left. In North America alligator lizards are found only in the West

gecko Geckos (Gecko Family, the Gekkonidae):  chubby-looking, often flat-bodied lizards, usually with toe pads enabling them to climb walls. Most geckos have thin, soft skin that tears easily, and their tails break of very easily; geckos are the most vocal of lizards; most species lay two eggs at a time;  found in the Deep South and the Desert Southwest

whiptail Whiptails (Whiptail & Racerunner Family, the Teiidae): long, very slender and fast lizards, often with narrow stripes running from head to tail; found in the southwestern U.S. Whiptails and racerunners are found in the same family and for the most part there's not much difference between them, except for where they are found. The Whiptail & Racerunner Family, the Teiidae, is confined to the new World, and, while we have a nice selection in the US, the family  is most abundant in South America.

racerunnerRacerunners (Whiptail & Racerunner Family, the Teiidae): like the whiptails, but found in the southeastern and central U.S; both whiptails and racerunners are egg-layers.In a few species in this family all individuals are females -- there are no males. Females lay unfertilized eggs that hatch into more females. The individual in the picture is the Six-lined Racerunner, the only  native member in the family found in Eastern North America. Several other racerunner species can be encountered in the West.

Ground Skink, Scincella lateralis, photo by Jerry Litton of Jackson, MississippiSkinks (Skink Family, the Scincidae): thick-bodied, typically with stripes running from head to tail, but the stripes aren't as narrow as among the whiptails and racerunners; some species have amber-colored lower jaws; found on every continent but Antarctica. Shown here is the Ground Skink, Scincella lateralsis, found from New Jersey south through Florida, west to central Texas, north to Nebraska and Missouri. It's often seen in my garden in southern Mississippi, for it's diurnal (out during the day), and it likes to hang around my mulch. Amazingly, this species has been seen to bite off its own tail and eat it!

Gila Monster, Heloderma suspectum, image by Gary M. Stolz, courtesy of U.S. Fish and Wildlife Service Gila Monster (Gila Monster Family, the Helodermatidae): the only poisonous lizard, very thick and blunt-tailed, with bands running across the body, not lengthwise; in the Desert Southwest. Mostly nocturnal. The Gila Monster's venom is not injected into a victim's body, as happens with venomous snakes, but rather flows into the open wound as the lizard chews on its victim. The Gila Monster's eye-catching black and reddish/orange/yellow striped pattern constitutes a classic BEWARE message that higher animals (including us humans) seem to intuitively interpret as "keep away."