Why do lizards throats turn red?

Answered by Robert Dupre

Lizards, specifically some species of anoles, have a fascinating adaptation that causes their throats to turn red. This phenomenon is primarily observed in males and is known as a throat fan or dewlap. The purpose of this vibrant display is two-fold: territorial defense and attracting a mate.

Territorial defense is an essential aspect of a male anole’s life. They establish and defend their territory against rival males, and the red throat plays a crucial role in this behavior. When a male anole feels threatened by another male encroaching on its territory, it extends its throat fan and displays its vibrant red coloration. This serves as a visual warning to the intruder, signaling that the territory is already claimed and defended. The bright red throat acts as a visual deterrent, indicating that the male anole is ready to defend its turf if necessary.

The red throat also plays a significant role in attracting a mate. During the breeding season, male anoles engage in elaborate courtship displays to attract females. The red throat is a vital component of this display. When a male anole spots a female of interest, it extends its throat fan and vibrates it rapidly. The combination of the red coloration and the movement creates an attention-grabbing display that is difficult for a female to ignore. The vivid red throat serves as a visual cue, indicating the male’s fitness and readiness to reproduce. It is believed that females are attracted to the brightest and most vibrant throats, as they indicate the presence of a strong and healthy mate.

Interestingly, the red coloration of the throat fan is not due to pigmentation but rather the reflection and scattering of light. The skin of the throat flap contains specialized cells called iridophores, which contain guanine crystals. These crystals act as tiny mirrors, reflecting and scattering light to create the vibrant red color. The intensity of the red coloration can vary depending on factors such as the angle of light, the male’s health, and its hormonal state.

The red throat of male anoles serves both as a means of territorial defense and attracting a mate. This adaptation allows males to visually communicate their dominance and fitness to rivals and potential mates. The vibrant red coloration is a result of light reflection and scattering from specialized cells in the throat flap, rather than pigmentation. Understanding the purpose and mechanism behind this unique feature provides us with valuable insights into the fascinating behavior and adaptations of lizards.