Among the world's weirdest reptiles, chameleons are renowned for their ability to change colour, for their revolving eyes, and their long sticky tongues. Around 140 species, from thumb-size creatures to the 60 centimetre-plus Parson's chameleon, roam the African bush and the forests of Madagascar. Award-winning photographer Chris Hellier shoots a dozen portraits of some of the most striking and colourful species.