Chameleons are known for their dramatic chromatic metamorphoses but do you know how and why they achieve this amazing feat? It was long believed that chameleons would change colour to blend into their surroundings as a form of camouflage. But actually, that is not the reason at all. The versatile reptiles adjust their pigmentation to regulate their temperature, communicate their mood and attract mates.
So while the first mystery has been solved, it’s onto the next one. How do they do it? Animals like squid and octopuses have sacs filled with various pigmentation that they accumulate and release to change their colour, and up until recently, scientists thought it was a similar situation with chameleons.
But in the past couple of years it was discovered that their method is somewhat more complex and fascinating – involving refracting nano salt crystals and iridophores in their skin that influence their colour by controlling the wavelengths of light that penetrates these multiple layers of skin, mixing in intensity to create their various vibrant hues.
As we know from our junior school art classes, primary colours can be mixed to create the full spectrum. And as we learned in science a ray of white light contains the 5 colours of the rainbow. Chameleons have yellow pigmentation in their skin and the iridophores refract blue light which is how they appear green in colour. When chameleons move the nano salt crystals in their skin around it affects the refraction of light that comes through their skin layers which influences their pigmentation. It all depends on how closely the crystals are clustered together or spread apart.
They do this by stretching and relaxing their skin which in turn moves and adjusts the lattice network of nanocrystals. Tightly clustered nanocrystals reflect short wavelengths like blue. When the distance between the crystals is increased they reflect longer wavelengths that include yellow, orange or red. It’s a complex and intricate process that allows chameleons to paint their own canvas.
Madagascar is home to half of the world’s 150 chameleon species and 59 of those can only be found on the island nation, making it an excellent destination to observe an incredibly diverse range of chameleons and the magnificent colours and patterns they can create. The studies that discovered these fascinating colour changing methods were actually done on Malagasy chameleons. Why not take a trip to Madagascar to see these colourful little critters up close?