If you’re a fan of lizards, you probably already know that there are some types of lizards — called chameleons — that can change their color. Have you ever wondered why — and how — they can do this?
Chameleons are lizards that are part of the scientific family called Chamaeleonidae. In addition to the ability to change color, chameleons have many other characteristics that make them special, including parrot-like feet, eyes that can look in two different directions at once, and long tongues and tails.
Chameleons come in many colors, such as pink, blue, orange, red, yellow, green, and turquoise. They can be found in Africa, Europe, Asia, and North America. There are about 160 different species of chameleons, and they can live in both rain forests and deserts.
Many people believe chameleons change colors to disguise themselves and hide from predators. However, chameleons are very fast — many can run up to 21 miles per hour — and can avoid most predators quite easily. Camouflage is thus only a secondary reason why most chameleons change color.
So why would they want to change colors? Scientists believe that chameleons change color to reflect their moods. By doing so, they send social signals to other chameleons. For example, darker colors tend to mean a chameleon is angry. Lighter colors might be used to attract mates.
Some chameleons also change colors to help their bodies adjust to changes in temperature or light. For example, a chameleon that gets cold might change to a darker color to absorb more heat and warm its body.
For many years, scientists believed that chameleons change their color by manipulating specialized cells — called chromatophores — that contain different colors of pigment. For example, when a chameleon wants to convey a particular mood or message, its brain sends a message to its chromatophores, which then move pigments around to change the chameleon’s color.
Today, researchers believe that pigments aren’t the only mechanism chameleons use to change their colors. While pigments can account for warmer tones, such as greens, they can’t explain brighter tones, such as reds and yellows.
Recent studies have shown that chameleons also have a special layer of cells — called iridophores — under their skin. These special cells, which contain pigment and reflect light, are made up of hundreds of thousands of guanine crystals. Chameleons can relax or excite their skin, causing these special cells to move and change the structure. Researchers found that, when this happens, these cells act like prisms, reflecting different wavelengths of light to create the variety of tones we see.
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