Thursday, June 27, 2013

Chameleons & Changing colors

Chameleons are lizards belonging to family called Chamaeleonidae. When we think of Chameleons, the first thing that strikes to mind is their ability to change colors.

Change of colour to camouflage!!! Not really!!!

It’s a popular belief that Chameleons change the color to blend with nature and to hide from predators. But camouflage is not the primary reason for change in skin color. Changing skin color in Chameleons is associated with various factors such as their reactions to temperature, light, mood, aggression, health, mating behavior.

Each chameleon species has its own color range. In general calm chameleons show green color. They exhibit darker colors like bright yellow to show their anger. It also serves the purpose of threatening others. Male chameleons when want to mate, show lighter, multicolored patterns.  Female chameleons show black with orange strips or dark brown color when they are carrying eggs. Chameleons become darker to absorb the heat effectively and show lighter grey color to reflect the light. A sick chameleon appears pale due to lack of sufficient energy to change color.

Chameleon’s skin is transparent and below which there are three layers of chromatophores - the specialized cells containing coloring pigments. First layer has xanthophores(yellow pigments) and erythrophores(red pigments). Second layer contains iridophores or guanophores with guanine, exhibiting blue or white color. Third layer has melanophores, (melanin pigment), and is responsible for the intensity of color.

Changing color phenomenon explained...
Coloring pigments are stored in vesicles inside chromatophores. Signals from nervous system or the chemical release in the blood stream initiates release of pigments from chromatophores. Vesicles containing pigments will release the pigment that alters the skin color of chameleon.  When these pigments distribute equally in the chromatophore, intensity of the color will be higher. But if the pigments are located at centre of chromatophores cells, then it looks almost transparent. So these specialized cells will direct sun light to specific pigments which in turn reflected back in different colors.

Only chameleons? We humans too!!!
Chameleons are not the only species to show this color changing phenomena. Cuttlefish is one more example for changing skin color. And we, human beings also change color though not prominently as chameleons. We turn red during anger or embarrassment and pale during shock and ill health.

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