Have you ever walked into a pet store and been captivated by the array of reptiles, especially the lizards? Perhaps you’ve noticed a tank bustling with lively green and brown lizards, maybe even a sign that mentions “80 geckos and anole lizards altogether.” It’s easy to be intrigued by these creatures, and you might even wonder about taking one home. Among these pet store inhabitants, anoles and geckos are frequently encountered, and while they are both fascinating reptiles, they are quite different. Often, people mistake anoles for chameleons due to their color-changing abilities, but they belong to a distinct family with their own unique characteristics and natural history. Let’s delve into the world of anoles, particularly the green anole, to understand what makes them special and how they differ from geckos and true chameleons.
A Green Anole carefully observing its environment. Their alert posture is characteristic of their diurnal, active nature.
Green Anoles: Not Chameleons, But Still Masters of Color Change
When you observe a green anole, scientifically known as Anolis carolinensis, you might be struck by its ability to shift colors, sometimes displaying vibrant greens and at other times earthy browns. This color change is a fascinating adaptation, often leading to the common misconception that they are chameleons. However, green anoles are New World lizards belonging to the Iguana family, quite distinct from the true chameleons of Africa and the Old World.
True chameleons are renowned for their dramatic color changes and several other unique features, including specialized feet for gripping branches (two toes forward, two back, like parrots), independently moving eyes, prehensile tails, and projectile tongues for catching prey. In comparison, the green anole’s color palette is more limited, and they lack these other specialized chameleon traits. Despite these differences, the green anole is a remarkable reptile in its own right, perfectly adapted to its environment in the southeastern United States.
The Resilience of Green Anoles
Native to the southeastern United States, from East Texas to North Carolina and throughout Florida, green anoles are surprisingly resilient creatures. They have faced numerous challenges, including collection for the pet trade, habitat loss, and the introduction of their cousin, the Cuban or brown anole (Anolis sagrei). Ironically, while native to the US mainland, green anoles have become invasive in places like Hawaii, Japan’s Ogasawara Islands, and Guam. In Guam, however, they now face a threat from the introduced brown tree snake, highlighting the complexities of invasive species dynamics. There are even isolated populations of green anoles in California, further demonstrating their adaptability.
Although green anoles can turn brown, distinguishing them from brown anoles is relatively easy. Green anoles possess a longer, more slender snout, whereas brown anoles have shorter snouts. This is a key identifying feature, much like the difference between crocodiles and alligators. Brown anoles exhibit a wide range of brown shades, and females often have distinctive dorsal stripes. Juvenile brown anoles sometimes display an orange tinge on their heads. While brown anoles can change color from brown to black, they cannot turn green.
A Brown Anole showcasing its dewlap on a tree trunk. The dewlap is a vital tool for communication and territorial displays among anoles.
Both green and brown anoles possess dewlaps, foldable throat fans used for courtship and territorial displays. In brown anoles, the dewlap is typically orange, often rimmed or speckled with yellow. In Southwest Florida, the local subspecies of green anole, the southern green anole (Anolis carolinensis seminolus), has a pale cream-colored dewlap, contrasting with the reddish dewlap of the more common northern green anole (Anolis carolinensis carolinensis).
Diet and Behavior: Observing Anoles in Action
Anoles are primarily insectivores, feeding on bugs and other small invertebrates. They employ a quick “dash and seize” hunting technique, which can sometimes appear rather messy as they consume their prey with legs and antennae sticking out of their mouths. Interestingly, as relatives of iguanas, green anoles occasionally supplement their diet with nectar, pollen, and flower petals, hinting at the herbivorous tendencies of their larger iguana cousins.
The Spread of Brown Anoles and Competition
Brown anoles likely arrived in the Florida Keys in the 1880s and rapidly colonized the peninsula. The movement of landscaping materials during Florida’s population boom further accelerated their spread. Today, brown anoles are found in Louisiana, as far west as Houston, and into central Georgia. Their northward expansion is currently limited by colder winter temperatures, as they are less cold-tolerant than green anoles. However, this may change over time through natural selection or climate change.
In areas where green and brown anoles coexist, green anole populations often decline due to competition for food and habitat. While there is some natural resource partitioning, with brown anoles being more terrestrial and green anoles preferring higher, more arboreal zones, both species must come to the ground to lay eggs. Brown anoles are also more prolific egg layers, giving them a competitive edge. The presence of vertical structures like trees in suburban yards can favor green anoles, but many modern landscapes with expansive lawns offer little habitat for them.
Geckos: A Different Kind of Lizard
Many observers mistakenly identify both anoles and geckos as the same type of lizard. A simple nighttime flashlight check around your house eaves will reveal the key differences. Geckos, in contrast to the diurnal anoles, are nocturnal lizards with large eyes adapted for low-light conditions. They have padded, suction cup-like feet, a flattened body posture, and a distinctive, somewhat squiggly running motion. Most geckos in Florida are introduced exotic species, but they generally fill a different ecological niche than anoles, primarily competing with invasive Cuban tree frogs in urban environments.
The Knight Anole: A New Challenge
A more recent threat to anoles is the knight anole (Anolis equestris), the largest anole species, reaching up to 19 inches in length. Native to Cuba, knight anoles likely arrived in Florida in the 1950s. Initially confined to areas around Coral Gables, they have since expanded their range, becoming more commonly sighted in areas like Naples. Knight anoles are significant predators, preying on tree frogs, bird nests, and even other anoles, including green and brown anoles.
A Knight Anole expertly climbing. Their size and predatory nature pose a threat to smaller lizard species in their introduced range.
Knight anoles are entirely arboreal, rarely venturing to the ground except to move between trees. Their range is temperature-dependent, and they can become comatose in cold temperatures. However, if warmed, they can become surprisingly aggressive, hissing and biting, highlighting their formidable nature.
Evolutionary Adaptations and Survival
Green anoles may have a slight advantage over brown anoles in escaping knight anole predation due to their greater agility in treetops and ability to navigate slick leaf surfaces. Studies in evolutionary biology, such as those by Dr. Jonathan Losos, have demonstrated the remarkable adaptability of anoles. Experiments on Bahamian islets showed that brown anoles could rapidly evolve shorter limbs in just a few generations when faced with ground-dwelling predators that forced them into more arboreal habitats.
Anoles also possess the ability to shed their tails to distract predators, a process called autotomy, and then regenerate them. While this is a valuable survival mechanism, it comes at a cost, requiring energy for regeneration and temporarily affecting balance and agility.
Conclusion: Appreciating Anoles
Observing an anole in its natural habitat, as it leaps through foliage or surveys its surroundings, provides a glimpse into the fascinating world of these adaptable lizards. Whether you encounter them in a pet store, your backyard, or in the wild, understanding the differences between anoles and geckos, and appreciating the unique challenges and adaptations of anoles, enriches our understanding of the natural world. Perhaps seeing these creatures will even inspire you to create more vertical structure in your own backyard, planting trees and shrubs that can provide habitat for these resilient and captivating lizards.
