Spiny tailed Iguana

(Ctenosaura similis)


Spiny tailed Iguana IUCN LEAST CONCERN (LC)


Facts about this animal

Spiny-tailed Iguanas are large, bulky lizards with adult males reaching up to 50cm in body length and additional 50 cm in tail length. The coloration of adults can be silver-gray, gray, bluish, or peach, with infusions of red or dark orange. The dorsal surface shows black bands on a greyish or light brown 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. Most adults, especially males have black chevrons. Adult males have well developed dorsal crests (up to 15 mm high) and small dewlaps. The dewlap 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. The tails are ringed with rows of sharp, curved spines, hence the name spiny-tailed iguana. Ctenosaura similis can run in a bipedal fashion and are more terrestrial than arboreal. In general they are herbivorous, particularly on legume fruits, but are also known to have a diverse carnivorous diet that consists of small animals. They eat rodents, bats, frogs, small birds (and birds eggs), crustaceans and a variety of insects. Young animals are primarily insectivorous, switching into herbivorous habits as adults. The species becomes sexually mature at around 3 or 4 years. They congregate and mate during specific times of year that varies between populations. Male iguanas possess a pair of intromittent organs, the hemipenes. When not in use the hemipenes lie adjacent to the cloaca within the base of the tail. During sexual activity one hemipenes is everted by the action of muscles and fills with blood. In copulation, which follows courtship behavior, only a single hemipenis is inserted into the female's cloaca, and the sperm travel along a groove in the hemipenis. Retraction of the hemipenis is accomplished by drainage of the blood sinuses and activation of retractor muscles that invert the structure as it is withdrawn. The oviparous females then migrate to suitable areas to nest. After a gestation period of app. 40 days they dig a burrow about half a meter deep and lay 2 to 25 eggs. They then defend the burrow for some time to prevent other females from nesting in the same spot. The young iguanas hatch 3 to 4 months later and then take about a week to dig their way out of the nest. If they survive the first difficult years of life, when food is often scarce and predators such as hawks and owls are dangers, they can live more than 60 years.

Did you know?
These iguanas live in colonies, ruled by a pecking order: One male in the colony is dominant, and although the other males hold territories, they will only defend them against one another and not against the dominant individual. Territorial displays involve color changes, body inflation, jaw-gaping, "push-ups" or rapid nodding of the head, and sometimes, biting and tail thrashing battles. Larger males usually hold bigger and better territories and they mate more often. Combat often occurs when iguanas are attaining or defending a territory or a mate. The males always court, but they can only progress if the partner provides them with the right stimuli. The female must respond by species specific sexual stimuli. She must also signal that she is receptive-with mature ova ready for fertilization. The males often bite, scratch, or lick females that have signalled their receptivity.In parts of South America iguanas are hunted by men imitating the screams of hawks. The iguanas' reaction to the cries is to "freeze" and they are then easily caught.


Name (Scientific) Ctenosaura similis
Name (English) Spiny tailed Iguana
Name (French) Iguane à queue épineuse
Name (German) Schwarzer Leguan
Name (Spanish) Iguana rayada
CITES Status Not listed
CMS Status Not listed



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Range South Mexico (Yucatan), Nicaragua, Guatemala, El Salvador, Honduras, Belize, Costa Rica, Panama, Old Providence Island (Colombia), San Andres Island.
Habitat Mainly in bushy dry areas (found in particular around ruins, stone walls or rocky open slopes), but also in other ecosystems, like on trees of the coastal region.
Wild population Man and his domestic animals are inevitably destroying the iguanas' environments and their species. The domestic animals such as cows devour most of the vegetation, which are the food sources for the iguanas The spiny-tailed iguana is edible and is also a popular food for much of the rural population of Central America. In some areas, eating their flesh is considered potent "medicine", with the person deriving the iguana's strength after eating it. Also, the spiny-tailed iguanas are supposed to be a cure for impotence. In addition they are collected for the pet trade. However Ctenosaura similis is actually farmed with Iguana iguana (Green Iguana) and Basiliscus plumifrons (Plumed Basilisc). The farming of this species provides a monetary incentive in economically depressed countries and produces minimal environmental impact. It also provides a ready source of specimens for those who wish to keep Ctenosaura.
Zoo population 25 reported to ISIS (2007)

In the Zoo

Spiny tailed Iguana


How this animal should be transported

For air transport, Container Note 41 of the IATA Live Animals Regulations should be followed.


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Photo Copyright by
Ken Thomas

Why do zoos keep this animal

The spiny-tailedn iguana is not a currently threatened species. zoos keep it primarily for educational reasons as a large and conspicuous representative of the lizards, and as an ambassador species for the conservation of neotropical ecosystems.