The lizards known for a colorful throat fan called a dewlap are anoles. The dewlap is a flap of skin supported by modified cartilage from the hyoid apparatus, and anoles extend it from the throat as a highly visible signal.
Dewlaps vary widely among anole species in size, shape, color and pattern. In the Carolina anole, for example, the male’s dewlap is typically bright orange-red and much larger than the female’s. Some dewlaps can also reflect ultraviolet light, which anoles may see even though humans cannot.
Anoles use this throat fan for communication rather than breathing or feeding. A male may extend it while courting, defending territory or confronting a rival, often combining the display with head-bobbing, push-ups and an erect dorsal ridge. The color and movement can help anoles recognize members of their own species.
Anoles are sometimes called “American chameleons” because several species can shift between green and brown. They are not true chameleons, however, and geckos, iguanas and most other familiar lizards do not have the classic anole dewlap.