Chameleon colour is mostly signalling, not camouflage
Chamaeleonidae counts about two hundred Old World lizard species famous for shifting hues. Skin stacks chromatophores and iridophore crystal lattices that change spacing to flip reflected wavelengths. Social signalling and temperature control usually matter more than pure camouflage, though some species still tune colours to specific predators.
Independent eyes feed the brain two separate images until hunting locks them for stereo vision. Zygodactyl feet, a prehensile fifth-limb tail, compressed bodies, casques, and ballistic tongues complete the toolkit. Most species live in Africa—about half restricted to Madagascar—with outliers in southern Europe and southern Asia, plus introductions in Hawaii and Florida. Sizes span male Brookesia nana at twenty-two millimetres, among Earth's smallest reptiles, to Furcifer oustaleti males near sixty-eight point five centimetres. The Greek name means ground lion.
Layered xanthophores, erythrophores, iridophores with guanine nanocrystals, and basal melanophores mix chemical and structural colour. Exciting the crystal lattice widens gaps so reflected light swings from blue-tinged resting greens toward yellows, oranges, or reds. Functions include display, thermoregulation—darker to warm, lighter to cool—and camouflage whose importance varies by species. Smith's dwarf chameleon and other Bradypodion adjust differently for bird versus snake eyes; Hawaiian Jackson's chameleons show more communication colour and less anti-predator shift than Kenyan source populations.
Fossils reach Middle Paleocene China with Anqingosaurus about fifty-eight to sixty-two million years old; Miocene finds span Europe and Kenya. Molecular work points to mainland African origins with two oceanic colonisations of Madagascar, not a Malagasy cradle. Subfamily splits remain debated since nineteen eighty-six. Viviparity evolved twice by the Early Oligocene. Whether resting green or flashing rival reds, the famous wardrobe is active physics under hormonal and neural control—not mood rings.
Source: Chameleon
