Some lizards display a vibrant red throat, a captivating visual phenomenon. Many species, particularly those in the Anolis genus, use this bright coloration as a primary form of communication. This trait plays significant roles in their daily lives, acting as a dynamic signal in social interactions.
Anatomy and Appearance
The “red throat” in lizards is an extendable flap of skin beneath the lower jaw, known as a dewlap or gular fan. This structure typically lies folded when not in use, appearing as a loose pouch of skin. Lizards extend this flap by moving components of the hyoid apparatus, a structure of bone and cartilage in the throat, allowing them to rapidly unfurl the dewlap.
While often recognized for its red hues, the dewlap’s color can vary greatly among species. It may appear in shades of orange, yellow, blue, or even feature intricate patterns. The specific color and pattern of the dewlap differ between species and can vary within the same species based on factors like age or sex.
Key Roles in Communication
The dewlap serves as a crucial signaling tool, primarily facilitating communication. Male lizards use their dewlaps in sexual selection, displaying them to attract mates. The size, color, and vibrancy of the dewlap can convey a male’s health, vigor, and genetic suitability, making him more appealing to females.
Beyond courtship, the dewlap is instrumental in territorial defense. Male lizards display their dewlaps to intimidate rivals and assert ownership over their territory, often preventing physical conflicts. This visual warning helps establish dominance and maintain social order.
Dewlap characteristics also play a part in species recognition. The distinct patterns and colors of dewlaps help lizards identify members of their own species, which is particularly important where multiple species coexist. This helps prevent hybridization and ensures successful reproduction.
Display Behavior
Lizards employ specific behaviors to effectively display their dewlaps as dynamic visual signals. The dewlap is not merely extended; it is often rapidly extended and retracted in a series of flashes. This quick movement ensures the signal is highly noticeable.
These dewlap displays are frequently combined with other body movements, such as head bobbing and push-ups. Head bobbing involves rhythmic up-and-down movements of the head, while push-ups consist of lowering and raising the front part of the body. These coordinated actions amplify the visual message, making the lizard appear larger and more formidable.
The complexity and tempo of these displays can vary depending on the context. A rapid, aggressive sequence might signal a territorial challenge, while a more prolonged display could be part of a courtship ritual. The combination of dewlap extension, head bobs, and push-ups allows lizards to convey messages.
The Science of Color
The vibrant coloration of a lizard’s dewlap is due to specialized pigment cells called chromatophores, located within the skin. Xanthophores produce yellow and orange hues, while erythrophores are responsible for red colors. These pigments, such as carotenoids and pteridines, are often obtained through the lizard’s diet.
Structural coloration also contributes to the dewlap’s appearance. Iridophores, another type of chromatophore, contain light-scattering crystals that produce iridescent or blue hues by reflecting light. The arrangement and concentration of these pigment cells determine the dewlap’s specific color and pattern. The dewlap’s intensity and hue can also be influenced by factors such as health and hormonal levels.