Western Spiny-tailed Iguana

C. pectinata has distinctive keeled scales on its long tail, to which its common name refers. It is one of the larger members of the genus Ctenosaura, capable of growing to 1.3 m (4.3 feet) in total length (including tail), with females being slightly smaller than males at 1.0 m (3.3 ft). It is usually brown or grey-brown in coloration dorsally, with a yellowish ventral surface. It has a crest of long spines which extend down the center of its back. Hatchlings are often a bright green color with no body pattern, and darken as they age. Ctenosaura pectinata often (but not always) has an irregular piebald pattern on the head or dorsal areas. Although the tail may be banded with light and dark crossbands, C. pectinata typically lacks a clear or well developed crossband pattern on the body, which is often present in the similar appearing and closely related species Ctenosaura similis and Ctenosaura acanthura.Ctenosaura pectinata varies from gray to a brownish-black, with some males exhibiting yellowish colors, and females orange color, on the lateral sides of the body. The young are bright green and unmarked except for black tail bands, present also on adults.

C. pectinata is native to the coastal lowlands of Western Mexico from Sinaloa to extreme western Chiapas. It follows many valleys and canyons into lower elevations of the Sierra Madre Occidental and Sierra Madre del Sur, including extensive areas of the Rio Balsas Basin. This iguana has been introduced to Brownsville, Texas and South Florida and reproduces in the wild in several feral populations. On the south-eastern Florida coast, these iguanas have been found on Key Biscayne, Hialeah, and in Broward County. On the south-western Florida coast, it has been reported on Gasparilla Island, where in December 2007 the population was estimated to be 12,000 iguanas, descended from pets released by a resident in the 1970s. The iguanas are regarded as a nuisance there because they eat ornamental flowers and shrubs, prey on nesting birds and sea turtle eggs, and have been reported to chew through electrical cables. Some residents have speculated that the iguana's habit of burrowing tunnels in the sand could cause dunes and even seawalls to collapse and deprive the island of crucial protection from hurricanes. There is also a small introduced population at the Arizona-Sonora Desert Museum in Tucson, Arizona. It was established in the 1970’s and has remained confined to the museum grounds.

C. pectinata is a social lizard, which has adapted to living in groups as opposed to other species of Ctenosaura which tend to be solitary animals. These iguanas are excellent climbers, and prefer a rocky habitat with plenty of crevices to hide in, rocks to bask on, and nearby trees to climb. They are diurnal and fast moving, employing their speed to escape predators but will lash with their tails and bite if cornered. They are often found dwelling near or in towns in their native Mexico and where they have been introduced elsewhere. Juveniles consume a diet consisting mostly of insects. However, adults are primarily herbivorous, eating a variety of flowers, leaves, stems, and fruit, but they will opportunistically eat small animals, eggs, and arthropods.