Dewlaps

Reptiles and birds

Many reptiles have dewlaps, sometimes called throat fans, most notably the anole family and Sitana genus of lizards, which have large skin dewlaps they can extend and retract. The anole family has been found to have enhanced vision for color and depth perception. This family is able to see dewlap coloration from a distance, giving the dewlap use and importance. These dewlaps are usually of a different color from the rest of their body and, when enlarged, make the lizard seem much bigger than it really is. The dewlap is primarily used when indicating territorial boundaries and for males to attract females during the mating season. The pigments generating this color are pterins and carotenoids. These two pigments are the most easily seen through the anole's eyes. Pterin and carotenoid pigments are located throughout the tissue of the dewlap, creating yellow and red hues. Lizards usually accompany dewlap movement with head bobs and other displays. The dewlap moves through extension and contraction. The muscles creating this movement are the ceratohyoid muscles and are connected to the hyoid apparatus in the throat and larynx area. Though the purpose of these displays is unclear, the colors of the dewlap and the movements during the displays are thought to be a way of standing out against visual background noise.