Ctenosaura similis, commonly known as the black spiny-tailed iguana, black iguana, or black ctenosaur, is a lizard native to Mexico and Central America that has been introduced to the United States in the state of Florida. It is the largest species in the genus Ctenosaura and has been recorded as the fastest-running species of lizard.
Black spiny-tailed iguana have distinctive black, keeled scales on their long tails, which gives them their common name. They, along with C. pectinata, are the largest members of the genus Ctenosaura. The males are capable of growing up to 1.3 meters (4 ft 3 in) in length and the females are slightly shorter, at 0.8–1 meter (2 ft 7 in–3 ft 3 in). They have a crest of long spines which extends down the center of the back. Although coloration varies extremely among individuals of the same population, adults usually have a whitish gray or tan ground color with a series of 4–12 well-defined dark dorsal bands that extend nearly to the ventral scales. Males also develop an orange color around the head and throat during breeding season with highlights of blue and peach on their jowls.
In some parts of Central America, the black spiny-tailed iguana, colloquially called the “chicken of the trees,” is farmed alongside the green iguana as a food source and for export for the pet trade [see iguana meat]. Although it is heavily hunted it does not appear to be endangered in any of its native territory.