Revealed: the chameleon's disguise

Who hasn't dreamed of having a chameleon as a pet? Just me? Oh, ok then. Anyway, I've never understood the the biology that allows them to change colour dependant on mood or surroundings, so I thought I'd do a little research... I discovered that chameleons have a transparent outer skin, below which there are 3 layers of specialised chromatophore cells with chemical pigments in their cytoplasm. In the top layer, the chromatophores used are known as xanthophores and erythrophores, which contain yellow and red pigments. The second layer contains iridophores and guanophores, which contain guanine and contain the blue/white pigments. The 3rd and deepest layer of chromatophores, known as melanophores, have a slightly different and all together more interesting function. They are the cells which control how much light is reflected back from these 3 layers, to adjust for light intensity. The intensity of the colours given off is determined by the distribution of pigment molecules within the cells- if these molecules are spread all over the cytoplasm, the colour given off is more vibrant. But the chameleon can also make these cells transparent by concentrating the pigment in the centre of the cell. The reptile is able to rapidly reallocate the pigment molecules, allowing the colours to shift wildly like a bad LSD trip. But why go to all this trouble to develop such a mechanism? Many believe that it is so chameleons can blend in with their environment, however for the majority of chameleons this is not the case. Most species use their colour change ability to signal to other chameleons their physiological condition and their emotions; for example they show darker colours when angry, to intimidate foes. The Namaqua chameleon species even uses the ability to help regulate its body temperature (homeostasis yo!), turing a light grey colour during the heat of the day to reflect infra red radiation from the scorching desert sun. As Adam Savage might say: MYTH BUSTED! Woa Woa Woa, hold your horses there! Why do chameleons bother with such a complicated mechanism, which could be almost entirely replaced by simple body language to portray emotions? Most of the animal kingdom uses body language for intraspecies communication. However I have a theory: because chameleons rely on an element of stealth and patience to catch prey and evade predation, they cannot afford superfluous motion which may give them away to other species. Therefore they use colour changes which not all predators/prey have the optic capability to see, in order to communicate. That is their ecological niche. It all fits rather well doesn't it? Although I can't prove this hypothesis without data...this isn't Philosophy! (joking).