Anole lizards, commonly observed in various warm regions, possess a distinct feature: a colorful throat fan known as a dewlap. This unique structure, often vibrantly colored, extends from beneath the anole’s chin. This article explores the dewlap’s physical makeup, how it operates, and its varied roles in the life of an anole.
Anatomy and Mechanism of the Dewlap
The anole dewlap is a flap of skin on the underside of the lizard’s throat. This skin is supported by cartilaginous rods that connect to the hyoid apparatus, bones in the throat.
When an anole displays its dewlap, muscles connected to the hyoid apparatus contract. This action pushes the skin flap outwards, extending the dewlap. When the display is complete, these muscles relax, retracting the dewlap against the throat.
Functions of the Dewlap Display
Anoles primarily use their dewlap displays for communication, particularly for attracting mates and defending territory. Male anoles often extend their dewlaps to signal their presence and fitness to potential female partners. The bright colors and patterns of the dewlap can convey information about the male’s health and genetic quality, influencing female choice.
During courtship, the dewlap display is often accompanied by head-bobbing movements or “push-ups.” These actions enhance the signal’s visibility and impact. These displays are a direct form of visual communication, facilitating reproduction.
Dewlaps also serve as a warning signal to rival males, delineating and defending territory. When an anole encounters another male, extending the dewlap, often with aggressive posturing, communicates dominance and a willingness to defend its space. This visual intimidation can prevent physical confrontations, establishing boundaries without direct combat.
Color Variation and Identification
The color, pattern, and size of an anole’s dewlap are often specific to its species, acting as an identifier. For example, the green anole typically exhibits a solid pink or red dewlap, while the brown anole often displays an orange-red dewlap bordered with yellow. This coloration helps anoles distinguish between members of their own species and others, important for successful mating and avoiding territorial disputes.
Dewlap characteristics also show differences between sexes, a phenomenon known as sexual dimorphism. Male anoles possess dewlaps that are larger and more brightly colored than those of females. Female dewlaps may be small, less vibrant, or even absent in some species. This distinction further emphasizes the dewlap’s role in species recognition and sexual signaling.