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.
Diet and behavior
Black spiny-tailed 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. The Guinness Book of World
Records lists the running speed of this species at 21.7 mph or 34.9 km/h making it the world's fastest
They are primarily herbivorous, eating flowers, leaves, stems, and fruit, but they will opportunistically eat
smaller animals, eggs, and arthropods. Juveniles tend to be insectivores becoming more herbivorous as they
The black spiny-tailed iguana is native to Central America, and has the widest range of all Ctenosaura
species from the Isthmus of Tehuantepec to northeastern Nicaragua and western Panama on the respective
Atlantic and Pacific coasts. It is commonly found throughout Costa Rica, Honduras and has been reported in
Colombia. In addition to its varied appearance it may interbreed with other Ctenosaur species throughout
The black spiny-tailed iguana has been introduced to South Florida and reproduces in the wild in several
feral populations. On the south-eastern Florida coast, black spiny-tailed iguanas have been found on Key
Biscayne, Hialeah, and in Broward County. On the south-western Florida coast, it has been discovered on
Gasparilla Island and in adjacent areas, throughout Lee and Charlotte counties. This iguana has also been
introduced to several islands in the Caribbean. As this species will opportunistically feed on small
vertebrates, such as fish, rodents, eggs, birds, and even hatchling sea turtles it may pose a threat to
endangered native species.
Mating generally occurs in the spring. Males show dominance and interest by head bobbing; eventually the
male will chase the female until he can catch her and subdue her. Within eight to ten weeks, the female will
dig a nest and lay clutches of up to 30 eggs. The eggs hatch in 90 days with the hatchlings digging their
way out of the sand. These juveniles are typically green with brown markings, although all brown hatchlings
have been recorded as well.
Zoológico de Vallarta A. C.
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