#140 Chameleons (English)

All you’ve ever wanted to know about chameleons

Chameleons are fascinating creatures, part of the reptilian family, known for their ability to change colour. They are commonly found in Madagascar, Africa, Spain, Portugal and Asia in rain forests, savannas, semi-deserts and steppes. The typical diet consists of insects and birds. Their main tool is their tongue which can be twice as long as their bodies! There are 171 species of chameleons and as a result there is an extreme variety in size. The largest being the Parson’s chameleon which can grow up to 69.5 centimeters long, and the smallest which grows to just 16 millimeters long known as the leaf chameleon. The leaf chameleon is one of the smallest vertebrates discovered and is so small it can sit comfortably on the head of a match stick!


Now let’s get to the age old question – why and how do chameleons change colour?! Well often we’re told that chameleons change colour to camouflage into their surroundings. Although this seems to make sense it is not the real reason explaining their nifty skills. The rapid colour change is caused by the adjustment of special skin cells. Chameleons rely on structural changes that affect how light reflects off their skin. The cells involved are called iridophore cells. These contain pigment as well as reflecting light. There are two thick layers of these cells which contain nano-crystals, all of different shapes and sizes. These “crystals” are key to the dramatic color shifts. The arrangement of the upper cell can be stimulated through excitement or relaxation leading to a change in colour. When the skin is in the relaxed state, the nano-crystals  are very close to each other causing the cells to reflect short wavelengths. In instances of excitement they are further apart and thus longer wavelengths are reflected. Only adult male chameleons change color while females and young chameleons are seemingly more dull-colored and have a very reduced upper layer of iridophore cells. Colour change is common when a chameleon faces a rival male or when they are trying to attract a female.
Another interesting feature of the chameleon is their independent eye movement. They can look in two directions at the same time as well as having 360 vision. Cool right? Their eyes are similar to that of a camera lens as they can focus quickly enlarging images.
McA