The way in which chameleons change colors is similar to how mixing different colors of paint creates new colors. In general, chameleons change colors by using chromatophores and melanin. Chromatophores are cells that contain pigment, or color; these cells have two layers, with the top layer containing red or yellow pigment and the bottom layer containing blue or white pigment. Melanin, on the other hand, is essentially a substance that determines the darkness of skin color, with the presence of more melanin causing darker skin. When the autonomic nervous system (ANS), a part of the nervous system that controls involuntary functions of the body, tells the cells to expand or shrink, the different colors mix together much like paint and change a chameleon’s skin color.
Although chameleons have the ability to change colors, some species have limits on the range of colors that they can display. The same goes for the range of patterns that they can display as well. In general, most chameleons are able to change among the colors green, black and brown. Some chameleons can change into an array of other colors as well, with the most vibrant color changes usually appearing in males when they are looking and ready to mate.
While the purpose of some patterns is to help chameleons blend in with their surroundings, it is a very common misconception that chameleons change colors to camouflage. This misconception is understandable, since chameleons can change colors and very much resemble their surroundings. For example, a chameleon with certain patterns and colors can blend in very well with a branch. In actuality though, chameleons change colors in reaction to such environmental factors as light and temperature, as well as in reaction to their emotions or moods. The ability to change colors enables chameleons to adapt to their surroundings and become more comfortable and also helps them communicate with each other.
Chameleons change colors to reflect or absorb light and temperature. When lying under the hot sun, for example, chameleons can change into a lighter color to reflect the brightness of the sun. As for temperature, when it is cold out, chameleons can become darker in color so they might absorb as much heat as possible. In general though, most of the time color changes occur because of changes in mood. As such, when chameleons change colors, they might be doing so because they are expressing their emotions, such as anger or fear.