Chameleons (family Chamaeleonidae) are a distinctive and highly specialized clade of lizards. They are distinguished by their zygodactylous feet, their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues, their swaying gait, the possession by many of a prehensile tail, crests or horns on their distinctively shaped heads, and the ability of some to change color.