How to Tell These Costa Rican Lizards Apart
Costa Rica is home to a stunning array of reptilian wildlife, and two of the most commonly spotted large lizards are the Green Iguana (Iguana iguana) and the Ctenosaur (Ctenosaura similis), often called the Black Iguana. While visitors may easily confuse these impressive reptiles at first glance, they have distinct differences in appearance, behavior, and habitat preferences.
If you’ve ever wondered how to tell them apart, here’s your guide to understanding these fascinating lizards.
Green Iguana (Iguana iguana)
Appearance:
Green Iguanas are typically bright green when young, though adults can vary in color from green to brown, gray, or even orange during breeding season. They have a long, slender body with a pronounced dewlap (the loose skin hanging under their throat) and a row of spines running down their back and tail.
Habitat & Behavior:
Green Iguanas prefer humid environments near rivers, mangroves, and rainforests. They’re excellent climbers and are usually found high in the trees. These iguanas are primarily herbivorous, feeding on leaves, flowers, and fruits.
Fun Fact:
When threatened, Green Iguanas can drop from treetops into rivers below, swimming gracefully to safety.
Best Places to Spot:
Tortuguero National Park, Manuel Antonio National Park, and the Osa Peninsula.
Ctenosaur (Ctenosaura similis)
Appearance:
Also known as the Black Iguana, the Ctenosaur sports rough, grayish-black scales with darker bands along the body and tail. Males often have spiky crests along their back, which give them a dinosaur-like look. They are more heavily built compared to Green Iguanas.
Habitat & Behavior:
Ctenosaurs thrive in drier, open habitats like rocky outcrops, dry forests, and even urban areas. Unlike their arboreal cousins, these iguanas are typically ground dwellers but are agile climbers when needed. They’re omnivorous, consuming a mix of fruits, flowers, insects, and small animals.
Fun Fact:
Ctenosaurs are considered the fastest lizards on Earth, capable of running up to 21.7 miles per hour (35 km/h).
Best Places to Spot:
Guanacaste’s dry forests, Palo Verde National Park, and beachside cliffs around Tamarindo.
Key Differences at a Glance:
| Feature | Green Iguana (Iguana iguana) | Ctenosaur (Ctenosaura similis) |
|---|---|---|
| Color | Bright green to brown/orange | Gray to black with dark bands |
| Size | Up to 6.5 feet (including tail) | Up to 5 feet |
| Preferred Habitat | Humid rainforests, riversides | Dry forests, rocky areas, urban |
| Diet | Herbivore | Omnivore |
| Behavior | Arboreal, shy | Ground-dwelling, bold |
| Distinctive Feature | Dewlap and back spines | Spiky crest and rugged appearance |
While both the Green Iguana and Ctenosaur are impressive members of Costa Rica’s reptilian community, they lead very different lives and have distinct appearances.
Next time you’re exploring Costa Rica’s wild trails or even relaxing by the beach, see if you can spot both of these lizard legends — and impress your fellow travelers by knowing exactly which is which!