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How and Why Do Chameleons Change Color?

Chandramita Bora
Chameleons can change their skin color due to the presence of specialized pigment cells beneath their transparent outer skin. A change in skin coloration is usually induced by factors like light, temperature, and mood of the chameleon.

Did You Know?

Some chameleons can change their skin color in less than 20 to 30 seconds.
Chameleons have several interesting characteristics, but what makes them so special and distinct is their ability to change color. Apart from this unique ability, this highly specialized clad of lizards possess eyes that can move independently from each other, enabling the reptile to look in two different directions simultaneously.
Contrary to popular belief,not all chameleons can change their color.Among those which possess this quality,some can change their skin coloration just a few shades, to green, brown, or gray. However, a few species of chameleons can literally change to almost any color.So,let's find out more about chameleons, and why and how they change the color of the skin.
About Chameleons

There are approximately 160 species of chameleons having different skin colors, right from gray, brown, and green, to pink, blue, red, yellow, orange, purple, and turquoise. Chameleons can be identified by the presence of horn-like projections or large crests on their heads.
They possess long extrudable tongues that can be squeezed out in an instance to catch prey. Several species of chameleons possess tails, known as prehensile tails, that are uniquely adapted for grasping.
The eyes of this reptile are also unique in the sense that each eye can move independently from each other. Chameleons can be mostly found in warm habitats from Africa and Madagascar, to south Asia and southern Europe.

Why Do Chameleons Change Color?

➤ Contrary to popular belief, chameleons usually do not change their color to camouflage or to match the color of their surroundings. Each species can change their skin color within a specific range, and for most of them, this range is green, brown, or gray. Coincidentally, these are the usual colors of their surroundings as well.
➤ In chameleons, a change in color is usually induced by factors like their mood and health. They can also alter their skin color to adjust to a change in temperature and the light conditions of their surroundings. Light usually reflects off their skin changing the color. When a chameleon gets cold, it makes itself flat and turns to a darker color, so that it can absorb more heat.
➤ Sometimes, chameleons change their skin coloration to communicate. For example, an angry chameleon can turn bright yellow or red to warn other chameleons, while a calm one may appear pale green. Similarly, a sick chameleon can also appear pale, due to lack of energy. On the other hand, there are certain species of chameleons that can change their skin color to a combination of various bright shades at the time of mating.

How do Chameleons Change Color?

➤ Chameleons can change their skin coloration with the help of specialized pigment cells, known as chromatophores. There are mainly three layers of cells that lie beneath the transparent outer skin of chameleons. Some of these cells contain pigments, while others reflect light.
➤ The first layer of chromatophores contains yellow and red pigments. The chromatophores that contain yellow pigments are known as xanthophores, while the cells that contain red pigments are called erythrophores.
➤ The second layer of chromatophores are known as iridophores. These pigment cells contain colorless stacks of platelets or crystals, which can reflect and scatter light. The iridophores can produce bright green and blue color by polarizing light.
➤ The last layer of pigment cells are the melanophores, which contain melanin granules that can move within a cell. When the melanin granules remain concentrated in the center of a cell, the skin appears pale. But, when they are distributed throughout the cell, skin of the chameleon becomes intensely colored. The color of a chameleon is thus determined by whether the melanin granules are clustered in the center, or distributed fully or partially inside the melanophores. The melanophores can also regulate the amount of light that is reflected.
➤ The iridophores that lie beneath the yellow-pigmented cells also play an important role in changing the skin color of chameleons. A change in the arrangement of the stacks of platelets and crystals within the iridophores can alter the way in which they reflect and scatter light. Thin in turn, can change the color of the skin.
➤ The entire of process of changing skin coloration is regulated by certain hormones released by the brain. These hormones control the melanophores, and affect the distribution of melanin granules inside them. They also regulate the contraction and expansion of the chromatophores.
➤ When the chromatophores of a particular color get expanded, a chameleon's skin acquires that color. For example,an angry chameleon can appear red, due to the expansion of the erythrophores. Once the chameleon calms down,the erythrophores contract and the blue light gets reflected through the yellow-pigmented layer.As a result, the skin color becomes green.