Geckos are known for their habit of licking their eyes. This common behavior prompts curiosity about its purpose. Understanding why geckos engage in eye-licking reveals adaptations that allow these creatures to thrive in various environments.
Unique Eye Anatomy
Many gecko species possess a specialized eye structure that differs from animals with movable eyelids. Instead of blinking, these geckos have a transparent, protective scale covering each eye, known as a spectacle or brille. This spectacle safeguards the eye from dust, debris, and injury. Unlike an eyelid that can blink, the spectacle remains stationary, requiring an alternative method for maintenance. Not all gecko species share this trait; some, such as the leopard gecko, possess functional eyelids and do not typically lick their eyes for cleaning.
Cleaning and Moistening
The primary reason geckos lick their eyes is for cleaning and moistening. The gecko’s long, agile, and often sticky tongue serves as an effective tool for the spectacle. When a gecko licks its eye, its tongue sweeps across the transparent surface, removing dust, dirt, and particles. This action also helps to clear away shed skin. The saliva deposited by the tongue keeps the spectacle hydrated, preventing it from drying out and becoming opaque, which would impair the gecko’s vision. Maintaining clear and moist eyes is important for geckos, allowing them to navigate their surroundings, locate food, and detect threats.
Sensory Exploration
Beyond hygiene, eye-licking can also contribute to a gecko’s sensory perception. Like many reptiles, geckos use their tongue to collect chemical cues from their surroundings. These chemical particles, which may include scents from prey, predators, or other geckos, are transferred by the tongue to a specialized chemosensory organ in the roof of their mouth, called the vomeronasal organ, also known as Jacobson’s organ.
While the tongue primarily gathers cues by touching surfaces, it is plausible that airborne chemical particles could settle on the eye’s surface. When the gecko then licks its eye, these particles could be picked up by the tongue and transferred to the vomeronasal organ for analysis, providing the gecko with additional information about its immediate environment. This allows geckos to “taste” or “smell” their surroundings, aiding in crucial behaviors such as foraging and identifying other individuals.