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| Common Green Iguana, Iguana iguana Linnaeus, 1758. Top photo is a captive animal. The bottom two photos are a juvenile found sitting on a branch over Trinidad's Arima River. Hatchlings are 70-80 mm in body length. Adult body size to 580 mm, and a total length of 2 m may be attained. Ranges from Sinaloa, Mexico to southern Brazil, occurs on many Caribbean islands, and it has been introduced into Florida. These lizards are usually close to water, and sit in the vegetation along and over streams. When disturbed, they dive into the water to escape. While adults may be solitary, I have seen groups of large animals concentrated in trees over streams. Juveniles are usually on the ground during the day but climb into the vegetation to sleep. Iguanas are mostly herbivorous and feed on fruits, flowers, and foliage. They use hindgut fermentation to increase the number of calories they get from food, and this requires a community of symbiotic protists that are passed from adults to juveniles, when the juveniles inspect adult fecal matter with their tongues. Females lay 9-70 eggs in a burrow that may be two meters long and 300-600 mm deep. At some locations females use a communal nest that may have multiple entrances and 24 m of tunnels. Large birds, snakes, and cats all feed on iguanas. However, humans also eat them and over much of its range Iguanas are hunted for meat and eggs. |
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| Chuckwalla, Sauromalus obeus (Baird, 1859). Photographed in Arizona. Chuckwallas are rock dwelling iguanids of the Sonoran and Mojave deserts. They range from eastern California and southern Nevada and Utah southward to Arizona, Baja California and northwest Sonora, Mexico. Adult body length reaches 228 mm. They prefer rock outcrops with boulders and uses the crevices to escape predation, wedging themselves between the rocks and inflating their body to avoid extraction. They bask in mid morning and feed on the flowers that are in the vicinity of their burrows or hides. Coloration is variable, the male that is black with the bright orange tail and the female below it are from an area south of Phoenix, Arizona. |
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| The Black Iguana or Spiny Tailed Iguana, Ctenosaura similis (Gray, 1831). Photographed in northwest Costa Rica. Adult males reach 1300 mm in total length, females are somewhat smaller. They range from central Mexico to Panama, and use lowland dry and wet forests, including areas that have been cleared for pasture. Black iguanas may also occur in city lots and gardens. Rocky outcrops, fallen trees, and fences are often used as basking sites. Juveniles are insectivorous and bright green (bottom photo) and are easily mistaken for young common iguanas. Adult Ctenosaura are herbivorous. Like the green iguanas they are used for food, and also for traditional medicines. |
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| The Desert Iguana, Dipsosaurus dorsalis Baird and Girard, 1852. Photographs of captives from Arizona. Desert Iguanas inhabit the Mojave Desert regions of California, Nevada, and western Arizona, and range southward to Baja, Sonora, and Sinaloa, Mexico. Habitats used include sand flats and creosote bush hummocks. Like most iguanids they are mostly herbivorous and feed on the bright yellow flowers of the creosote bushes, however they will also eat insects. These lizards love heat and control their body temperature by moving from sun to shade, or to their burrows. They may achieve body temperatures exceeding 40 degrees Celsius, one of the highest for any vertebrate. Females lay 2-10 eggs that hatch in September, and may double clutch in some years. These lizards are often seen racing around from one shade patch to another at mid day, as they do they have femoral pores that release a chemical that marks where they have been, this molecule probably provides chemosensory information and well as visual information since it fluoresces. It is one of the smaller members of the family, reaching a total length of 400 mm. Dipsosaurus is a basal lineage within the Iguanidae. |
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| Iguanids are found mostly in the Western Hemisphere from the southwestern USA southward through Central America and into South America to Paraguay. They also occur in the Galapagos Islands and in the West Indies. One genus is found in the Fiji and Tonga Islands. The South Pacific species presumably rafted to the islands from mainland South America, as did the Galapagos species. There are eight living genera with about 29 species in the family, in addition to three fossil genera. Adult iguanids are herbivorous, some of the juveniles are more omnivorous. The Galapagos Marine Iguana forages in the ocean for algae. All are oviparous, and several species are communal nesters. They range in size from about 140 mm to about 700 mm in body length. |
