AT A GLANCE
- Common Name: Mexican Spiny-tailed Iguana
- Scientific Name: Ctenosaura pectinata
- Category: Reptiles
- Subcategory: Lizards
- Range: Western Mexico, along the Pacific coastal lowlands and foothills from Sinaloa south to Oaxaca and into the Balsas River depression
- Habitat Type: Tropical dry deciduous forests, coastal thorn scrub, rocky canyons, agricultural stone walls, and cactus savannas from sea level up to 1,500 meters
- IUCN Red List Status: Least Concern
- Lifespan: 15 to 25 years
- Diet: Herbivorous/Opportunistic omnivore (leaves, flowers of cacti and legumes, wild fruits, pods, alongside insects, small lizards, and birds’ eggs)
- Average Size/Weight: Total length 75 to 120 cm; snout-vent length 30 to 45 cm; weight 1 to 2.5 kg
- Key Defining Feature: Heavy-bodied, formidable iguana featuring a muscular tail armed with whorls of razor-sharp, cone-shaped spiny scales, and a spiky dorsal crest running down its spine
Overview
The Mexican Spiny-tailed Iguana (Ctenosaura pectinata), locally known in Mexico as the ‘Garrobo’ or ‘Iguana Negra,’ is a powerful, heavily armored arboreal and rock-dwelling lizard native to the tropical dry forests of western Mexico. Belonging to the family Iguanidae, this robust reptile is renowned for its explosive sprinting speed and formidable defensive weaponry. Equipped with a thick, muscular tail studded with concentric rings of razor-sharp, spike-like scales, it can deliver punishing, bone-bruising tail whips that readily drive away coyotes and hunting dogs.
Biology and Physical Characteristics
Ctenosaura pectinata is a massive, muscular lizard with a deep, triangular head and a prominent throat fan (dewlap) that males flare during territorial disputes. Juveniles emerge as a dazzling, camouflage bright neon-green, but as they mature, their coloration transforms into a rugged, mottled mosaic of charcoal-grey, dusty black, and creamy-yellow with irregular pale cross-bands. A prominent crest of stiff, triangular, comb-like scales runs down the center of the back (pectinata meaning ‘comb-like’). The tail accounts for more than half its total length and is armored with distinct whorls of heavy, enlarged, sharply pointed spinose scales that form an impenetrable physical weapon.
Behavior and Ecology
Diurnal and avid heliotherms, Mexican Spiny-tailed Iguanas spend cool mornings basking high on tree branches, granite boulders, or old stone cemetery walls to elevate their body temperature. Despite their heavy, armored appearance, they are among the fastest lizards on Earth, capable of clocking burst sprint speeds of over 30 kilometers per hour to reach safety. When cornered inside a hollow tree trunk or rock fissure, the iguana turns around, wedges its armored body into place, and lashes its heavily spiked tail back and forth with ferocious speed, inflicting bloody lacerations on any predator attempting to grab it.
Conservation and Human Impact
The Mexican Spiny-tailed Iguana is evaluated as Least Concern by the IUCN Red List due to its broad distribution and resilience in agricultural and rural landscapes. However, wild populations face sustained localized pressure from traditional hunting for its prized meat and eggs, as well as significant habitat conversion from coastal resort development and cattle ranching.
Interesting Factoid
The Mexican Spiny-tailed Iguana is one of the fastest sprinting lizards on Earth, capable of running at nearly 20 miles per hour, and its heavily spiked tail can whip with such force that it can split the skin of a coyote.