Photo by Casey Gilman, U. Mass. Amherst

In addition to performing dewlap extensions, head bobs, and pushups, many anoles raise a dorsal crest during territorial disputes. Here, two Anolis sagrei males square off. The static dorsal crest serves to modify the appearance of active pushups and dewlap extensions, perhaps making the male appear larger and more imposing. It is unclear how the crest is controlled. Jenssen notes the lag period before the crest is raised and the persistence of the crest after a territorial bout is concluded; thus, the crest may be a response to adrenaline and under the control of the sympathetic nervous system. Note the tongue extension by the top lizard.