Green Iguana

Physical Characteristics

The Green Iguana is a large, arboreal herbivorous lizard native to Central and South America, and now widespread as an invasive species in Florida, the Caribbean, and parts of Southeast Asia. Despite its name, the species shows a range of colors and is instantly recognizable for its prominent spines, dewlap, and long tail.

Coloration:

• Juveniles are typically bright green with faint black banding on the body and tail.

• Adults vary by region and age—colors range from gray-green and olive to orange, brown, or even blue.

• Breeding males may display intense orange or rust coloration, especially on the legs, dewlap, and dorsal spines.

Head and Eyes:
Green Iguanas have a large, angular head with powerful jaws, a blunt snout, and prominent jowls in mature males.

• Eyes are lateral with round pupils and capable of detecting motion and color.

• A large subtympanic shield (round scale) is visible on the cheek.

Dewlap:
A large, hanging dewlap under the chin is used in thermoregulation, communication, and mating displays. It is extended in threat posture or when basking.

Body and Scales:
The body is elongated and laterally compressed, covered in tough, overlapping scales.

• A row of spiny dorsal scales extends from the nape down to the tail, more pronounced in males.

Tail:
The tail is extremely long and muscular, making up over half of the total body length. It is used for balance, defense (whipping), and swimming. The tail is banded with dark rings and can be autotomized (dropped) when escaping predators.

Limbs and Toes:
Iguanas have strong limbs with long toes and sharp claws, adapted for climbing trees, gripping branches, and digging burrows.

Size:

• Total Length: 4 to 6.5 ft (1.2 to 2 m), including tail

• Snout-to-vent length (SVL): 1.5 to 2.5 ft (45 to 76 cm)

Weight:

• Adults weigh 4 to 10 kg (9 to 22 lbs), with males generally larger and more robust than females

The Green Iguana’s combination of prehistoric appearance, color variation, and tree-dwelling build makes it one of the most distinctive and widespread reptiles in the Americas—and one of the most recognizable lizards in the world.

Reproduction

The Green Iguana follows a seasonal, oviparous reproductive cycle, marked by male territoriality, color change, and large clutch sizes. Reproduction is synchronized with dry and rainy seasons to ensure hatchling success.

1. Mating and Seasonality:

• Breeding usually occurs during the dry season (December to February), with egg-laying in late winter or early spring.

• Males become highly territorial, displaying bright orange coloration, aggressive head bobbing, dewlap extension, and tail whipping.

• Males may defend a harem of females and compete with other males for breeding rights.

2. Copulation:

• Mating follows brief but sometimes aggressive courtship, during which males may bite or hold the female.

• Copulation involves cloacal alignment and lasts several minutes. A single male may mate with multiple females during the season.

3. Egg-laying:

• Females lay their eggs 3 to 6 weeks after mating, digging long burrows (up to 1 m deep) in sandy or soft, sun-warmed soil.

• Clutch Size: Usually 20 to 70 eggs, with larger females laying more.

• Eggs are leathery, white, and oval, and incubate in the ground without parental supervision.

4. Incubation and Hatching:

• Incubation period: 90 to 120 days, depending on soil temperature and humidity.

• Hatchlings typically emerge with the arrival of the rainy season (May to July), when food is more plentiful.

5. Hatchlings:

• Neonates are about 6 to 8 in (15 to 20 cm) long and are bright green, with faint dark bands on the tail.

• They are completely independent and begin foraging and climbing immediately.

6. Sexual Maturity:

• Green Iguanas reach sexual maturity at around:
  – Females: 2 to 3 years
  – Males: 3 to 4 years

• Maturity depends on size, diet, and environmental conditions.

The Green Iguana’s large clutch size, seasonal timing, and early independence allow it to maintain robust populations across both native and introduced ranges, making it one of the most ecologically successful lizards in the Americas.

Lifespan

The Green Iguana is a long-lived reptile with a lifespan that reflects its large size, slow maturation, and adaptability. While vulnerable during early life stages, iguanas that reach adulthood can survive for decades in the right conditions.

Lifespan in the Wild:
In natural environments, Green Iguanas typically live 10 to 15 years, though some individuals may reach 20 years if they avoid predation and environmental stress.
Juveniles face high mortality due to predation by birds, snakes, mammals, and competition for food and basking space.

Lifespan in Captivity:
With proper care—including UVB lighting, a calcium-rich diet, ample climbing space, and regular veterinary attention—captive Green Iguanas may live 15 to 25 years, and some have lived past 28 years.
However, in inexperienced care, poor husbandry can lead to early death from metabolic bone disease, kidney failure, or malnutrition.

Threats to the Green Iguana:

• Predation: Eggs and hatchlings are especially vulnerable to birds of prey, snakes, mongooses, and domestic cats and dogs.

• Habitat Loss: Deforestation, urban expansion, and agriculture reduce nesting and foraging areas.

• Human Conflict: In some regions, they are hunted for meat or seen as agricultural pests, especially in their invasive range.

• Environmental Extremes: Cold snaps in non-native ranges like Florida can lead to mass mortality events, as iguanas are highly sensitive to low temperatures.

Despite these challenges, the Green Iguana’s high reproductive rate, wide habitat tolerance, and arboreal agility have made it one of the most resilient and successful large reptiles in both native and introduced ecosystems.

Eating Habits

The Green Iguana is a primarily herbivorous lizard, feeding on a variety of leaves, flowers, and fruits. Its digestive system is specially adapted for fermenting fibrous plant matter, making it a key arboreal browser in tropical ecosystems.

Diet:
Green Iguanas feed on a wide range of vegetation, including:

• Leaves of trees and shrubs (e.g., hibiscus, sea grape, mulberry, fig)

• Flowers, especially brightly colored species like bougainvillea and hibiscus

• Fruits such as mango, papaya, banana, cactus fruit, and figs

Occasionally, juveniles or malnourished adults may opportunistically eat:

• Insects

• Eggs

• Small lizards or carrion (though this is rare and not preferred)

Feeding Strategy:

• Green Iguanas are diurnal foragers, feeding during the day and basking to aid digestion.

• They typically forage in tree canopies, using strong limbs and sharp claws to climb and navigate between branches.

• Iguanas use serrated, leaf-cutting teeth to shear tough leaves and crush softer plant matter.

Digestive Adaptations:

• Their digestive tract includes a large, fermentative hindgut, where symbiotic bacteria break down cellulose.

• This slow digestion process requires frequent basking to maintain body heat and metabolic function.

Water Intake:

• Most hydration comes from moist leaves and juicy fruits, but they will drink from rain puddles or water disheswhen available.

• They are excellent at conserving water and can go several days without direct drinking in humid environments.

Feeding in Captivity:

• Captive Green Iguanas require a calcium-rich, oxalate-poor, plant-based diet consisting of:
  – Dark leafy greens (collard, mustard, dandelion)
  – Squash, zucchini, bell pepper
  – Limited fruit (as a treat)

• Animal protein should be avoided, as it can cause kidney damage and reduce lifespan.

The Green Iguana’s arboreal, plant-based diet, slow metabolism, and leaf-processing dentition make it a highly specialized tropical browser—one that shapes and depends on the health of forest canopy ecosystems.

Uniqueness

The Green Iguana is one of the most widely recognized reptiles in the world, celebrated for its prehistoric appearance, tree-dwelling lifestyle, and cultural significance. Its size, adaptability, and ecological role make it unique among lizards in both wild and urban landscapes.

Tree-Dwelling Giant:
Few lizards rival the Green Iguana in size and agility—reaching up to 6.5 ft (2 m) in length while remaining fully arboreal. Their ability to leap from trees into rivers, often from heights of 40–50 ft (12–15 m), makes them both graceful and fearless climbers.

Swimming and Escaping Abilities:
Although tree-based, Green Iguanas are strong swimmers and may use submersion as an escape tactic, holding their breath for over 30 minutes. Their long, muscular tails help propel them through rivers and mangrove lagoons.

Thermal Basking and Color Change:
Green Iguanas are masters of thermoregulation. They use sunbathing and color shifts (from dark to light greens or browns) to regulate body temperature. Males may turn bright orange during breeding season to signal dominance and mating readiness.

Subtympanic Shield and Dewlap Displays:
Unique among iguanas, Green Iguanas display a large round subtympanic scale (cheek patch) and a broad dewlap that they extend to communicate territory, alertness, or reproductive status—both to rivals and potential mates.

Pet Trade Icon and Invasive Success:
Once a staple of the exotic pet trade, Green Iguanas have been released or escaped into wild populations throughout Florida, the Caribbean, and parts of Southeast Asia. Their ability to thrive in urban areas, reproduce rapidly, and tolerate a variety of climates has made them both admired and problematic.

Cultural Symbol and Ecological Role:
In Central American cultures, iguanas are known as “gallina de palo” (chicken of the tree) and have been a traditional food source. Ecologically, they act as seed dispersers and folivores, impacting forest regeneration and plant dynamics.

The Green Iguana’s blend of bold coloration, arboreal grace, resilience, and symbolic presence makes it one of the most iconic and ecologically important reptiles of the tropics—and one of the few lizards with global recognition and influence.