Black Spiny-tailed Iguana

Scientific Name
Ctenosaura similis
Also Known As
Black Iguana, Common Spiny-tailed Iguana
Central and Southern Florida
Flowers, Leaves, Stems, and Fruit
Life Expectancy
19 Years
The Black Spiny-tailed Iguana

Photo 200032739 (c) Carlos G Velazco-Macias, CC BY-NC

Black Spiny-tailed Iguana conservation status - Invasive

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Black Spiny-tailed Iguanas in Central Florida

The black spiny-tailed iguana (Ctenosaura similis) is an invasive lizard that has established breeding populations in Central Florida. Often confused with the native green iguana (Iguana iguana), the black spiny-tailed iguana can be identified by its distinctive spikes, scales, coloration and habits.

This comprehensive guide provides detailed identification tips, biology facts, and prevention and control methods for black spiny-tailed iguanas in Central Florida. Read on to learn about black spiny-tailed iguana characteristics, reproduction, diet, impacts, signs of infestation, and professional removal options if you see these exotic lizards on your property.

Appearance and Identification

Black spiny-tailed iguanas can be distinguished from the similar-looking green iguana, especially at juvenile and adult stages

Adult Black Spiny-tailed Iguana

Photo 106911977 (c) Ty Smith, CC BY-NC

Adult Black Spiny-tailed Iguanas

  • Size: Adults reach up to 54 inches (137 cm) in total length, with the tail making up two-thirds of that length. They weigh around 9 to 17 lbs (4 to 8 kg).
  • Spikes: Large, keratin spikes extend along the back, tail, and sides. These become pronounced in mature iguanas.
  • Coloration: Adults lose the green and dark bands, becoming solid gray or black dorsal color with off-white on the underside. The throat may show orange coloration.
  • Head: Powerful bite strength with teeth adapted to an herbivorous diet. Eyes have golden irises with black pupils.
Juvenile Black Spiny-tailed Iguana

Photo 167598282 © panchoromo, CC BY-NC

Juvenile Black Spiny-tailed Iguanas

  • Size: Hatchlings are 4.5 to 6 inches (11 to 15 cm) long from snout to vent. The tail is equal to or longer than the body.
  • Scales: White spike-like dorsal scales form five rows down the spine and tail. These spikes are soft and flexible in young lizards.
  • Coloration: Juveniles are bright green with bold dark bands running across the body and tail. The underside is pale yellow or white.
  • Head: Triangular head with spiky scales around the neck that can be extended into a crown-like fringe for defense.

The green iguana lacks the distinctive spikes of the black spiny-tailed variety. The squat, heavy-bodied green iguana also has more orange coloration on the sides and underparts.

Maturation Rate

Young black spiny-tailed iguanas grow rapidly after hatching. They begin developing adult coloration around 8 months old as the spikes harden. At 1 to 1.5 years old, they reach sexual maturity and adult size. Rapid growth allows black spiny-tailed iguanas to reproduce early, fueling proliferation in warm Southern habitats.

Habits and Behavior

The black spiny-tailed iguana is diurnal, active during the daytime hours. They are expert climbers and prefer trees near water sources. Males stake out territory which may encompass female home ranges. They communicate using body signals and head bobs.

Black spiny-tailed iguanas dig burrows or occupy hollow logs, stumps, and crevices as retreats. These iguanas swim and dive well, escaping threats by going underwater. Their powerful tail is used as a weapon in defense. When threatened, they stiffen and extend the spiny scales to appear larger to predators.

Reproduction and Lifespan

Black spiny-tailed iguanas reach sexual maturity between 2 to 3 years of age. Mating takes place in fall or winter, with males courting multiple female partners. Females dig nests in burrows or soil, laying clutches of 16 to 30 eggs in early summer.

The eggs incubate for approximately 75 days before hatching in late summer. Black spiny-tailed iguanas may live up to 19 years in the wild. Their high reproduction rate allows populations to expand quickly with sufficient food and habitat available.