Monday, March 30, 2015

Chameleons: Your Secret is out….!!!!

We know that the Chameleons are lizards that are part of the scientific family called Chamaeleonidae which can change their colour… How do chameleons change their colour? Swiss scientists have found the answer to this riddle.

Most people believe that Chameleons blend with nature to escape from predators … But is it really so??  Chameleon can run up to 21 miles per hour and can avoid most predators quite easily.  Therefore camouflage is their secondary function. Light, temperature, and emotional state commonly bring about a chameleon's change in colour. The chameleon will most often change between green, brown and grey, which coincidently often match the background colors of their habitat. The amazing features of chameleon are more. They also have parrot-like feet, eyes that can look in two different directions at once and long tongues and tails.

Earlier claim was that chameleons change their colour by manipulating specialized cells called chromophores that contain different colors of pigment. But latest version is something interesting and new. The newest study shows that chameleons have a mobile “lattice” of nanocrystals on the surface of their skin, which come together and disperse thereby shifting the wavelength of light reflected by the reptile. Researchers reveal chameleons use futuristic nanotechnology to carry out their extraordinary colour changes.

To discover how the chameleons switch from one colour to another, the researchers employed both quantum physics and in evolutionary biology. Scientists from University of Geneva studied the panther chameleon (Furcifer pardalis), native to Madagascar, which has one of the most impressive colour displays in the chameleon kingdom. They studied the skin of the lizards using spectroscopy and have found that the lizards possess a layer of skin cells that contain floating nanocrystals. The tiny crystals called iridophores are roughly evenly spaced throughout the cell and this spacing determines the wavelength of light that the cells reflect. Iridophores contains nanocrystals made of guanine, one of the four key components of DNA.

The guanine nanocrystals are arranged in a lattice throughout the cell, the spacing of which determines the cell’s colour. I.e. chameleons switch colour from green to red by actively changing the spacing between these tiny cellular crystals. When the chameleon is calm, the crystals were found to be organised into a dense network, reflecting blue wavelengths most strongly. When excited, the chameleon was found to loosen its lattice of nanocrystals by about 30%, allowing the reflection of yellows or reds. The chameleons change the structural arrangement of the cells by relaxing or exciting the skin, which leads to a change in colour.

Besides the layer of iridophores an additional layer where the cells were much bigger and more chaotically organised is also spotted. This layer reflects infrared light which prevent the chameleon getting too hot in the tropical sun. I.e. why chameleon is really cool…

"Chameleons invented something completely new in evolution," Prof Milinkovitch of the university, said." They split the iridophores into two layers, one that is specialised for colour change... and one to reduce the amount of energy absorbed by the animal.

While the new study sheds some light on the chameleon, there's still a lot of confusion regarding the animal. The scientists are yet to work out how chameleons cause this change, but it could be due to cells shrinking or expanding, giving the crystals more or less space to fill. More investigations may need in this matter to unveil the mystery further…

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