Black Iguana

The ctenosaurs are large, bulky lizards with adult males reaching up to 18 inches long with a 18-inch tail. They are predominantly black but the dorsal surface may show black bands on a greyish background. Most have black mottling on their backs. The color may also lighten after basking in the sunlight with yellowish and orange markings becoming evident along the sides. Adult males and females are dimorphic. Adult males have well developed dorsal crests and small dewlaps. The dewlap, the crescent of skin that can be extended under the throat, is not inflated. A small bone bows out to extend the dewlap during times of threat, courtship, or while defending territory. Females lack obvious crests. There is considerable variation with age and sex and therefore identification may be difficult. The lizards have tails ringed with rows of sharp, curved spines, hence the name spiny-tailed iguana. The spines down the back are short. Juveniles tend to be olive-green becoming tan and then finally greyish as they grow.