Black Spiny Tail Iguana (Ctenosaura similis)

Scientific Name: Ctenosaura similis
Common Name: Black Spiny Tail Iguana

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Species Overview

Size: Adults typically reach 3–5 feet (0.9–1.5 m) in total length, with robust bodies and long, spiny tails.

Appearance: The Black Spiny Tail Iguana is a large, muscular lizard with a dark grey to black base coloration. Its distinctive tail is lined with pronounced spiny scales, which it uses for defense. Juveniles display lighter body tones with more prominent banding, which darkens with age. The head is broad and angular, and the body is covered in rough scales adapted to a rocky, arboreal, and terrestrial lifestyle.

Distribution: Native to Central America, particularly southern Mexico, Guatemala, Honduras, Nicaragua, and Costa Rica.

Habitat: Wild Black Spiny Tail Iguanas inhabit rocky outcrops, dry forests, scrublands, and open areas with abundant sun. They are primarily terrestrial but are excellent climbers. In captivity, they thrive in large enclosures with climbing structures, basking areas, and secure hiding spots.

Behaviour: This species is diurnal and highly active. They are territorial and can be aggressive toward conspecifics. Wild-caught individuals may be defensive, while captive-bred animals can become accustomed to human presence with proper handling. They are fast runners and capable climbers.

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Captive Care

Enclosure: Provide a large, secure enclosure at least 8 feet × 4 feet × 6 feet (2.4 × 1.2 × 1.8 m) for a single adult. Include climbing branches, rock ledges, elevated basking areas, and secure hiding spots. A deep substrate for digging and burrowing is recommended.

Temperature & Humidity:

• Basking area: 105–110°F (40–43°C)

• Ambient temperature: 85–95°F (29–35°C)

• Night temperatures: 70–80°F (21–27°C)

• Maintain moderate humidity of 50–70%, with daily misting or water access.

Lighting: Provide strong full-spectrum lighting and high-output UVB (10–12%) for 12–14 hours daily. UVB and heat gradients support calcium metabolism, healthy growth, and natural behaviour.

Diet: Offer a varied omnivorous diet consisting of leafy greens, vegetables, fruits, and occasional insects or small prey. Adults primarily consume vegetation, while juveniles require higher protein intake. Supplement with calcium and vitamins as needed.

Behaviour in Captivity: Black Spiny Tail Iguanas are active, alert, and fast-moving. They enjoy climbing and exploring their enclosure. Handling should be cautious, particularly with larger adults, due to their powerful tail and defensive nature.

Special Considerations: This species requires substantial space, climbing opportunities, and high temperatures. Secure, escape-proof enclosures are essential due to their speed and strength. Aggression between individuals is common.

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Taxonomy Note

The Black Spiny Tail Iguana (Ctenosaura similis) belongs to the family Iguanidae and is one of the largest species in the genus Ctenosaura. Known for its distinctive spiny tail and adaptability, it is a popular species for experienced reptile keepers.

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Genetics Note

There are no recognized morphs or selectively bred variants for the Black Spiny Tail Iguana. Natural variation is primarily in coloration and pattern contrast between individuals and age classes.