At least 134 chameleon species exist, about half of which live on the island of Madagascar. Although it is widely believed these lizards change the color of their skin to camouflage themselves by mimicking the surrounding environment, this is only part of the story. Chameleons also change colors to send signals to other chameleons nearby. Each species has a distinct range of color variation, and individuals can only understand the color codes of members of their own species.
Chameleon skin contains three layers of cells called chromatophores. These cells are filled with melanin of different colors: yellow and red closest to the surface of the skin, blue in the middle, and black at the bottom. Neurotransmitters in the chameleon's brain signal specific cells to expand or contract, which changes the color of the animal's skin. Scientists don't know whether the lizard consciously controls its color changes or if the process is completely autonomic.
Aggression or Submission
The territorial chameleon displays its dominance to interlopers using rapid flashes of vivid color, which may last less than 20 seconds. The panther chameleon's skin, for example, will change from its resting blue and green tones to red when the lizard is angry or threatened. Most species display dark or dull, muted colors to indicate submission. A male Meller's chameleon that is intimidated by another's display of dominance will change to dark, submissive coloring and shrink away.
A male chameleon also displays bright, vivid coloration to court a female. The male Meller's chameleon, for example, flashes red to show interest; the consenting female's skin changes to bright yellow with black and cream patterns. If a male panther chameleon is looking for a mate, it attempts to impress the female with brilliant blue, green, orange, yellow, red and white coloration. The pregnant female's skin turns dark brown or black to indicate the lizard is unavailable for mating.
Identity and Well-Being
A chameleon's skin color also communicates the lizard's body temperature, stress level, nutrition and even mood. A calm chameleon may have a green coloration, and its resting coloration typically is designed to camouflage the lizard to some extent in its surrounding, protecting it from predators. A veiled chameleon, for example, has adapted colors at rest that mimic the browns and greens of its arboreal desert habitat. A chameleon's coloration may also indicate if it is ill or injured.
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