Chameleons change color by altering the spacing of nanocrystals within specialized skin cells called iridophores, which reflect light differently based on the spacing. When the crystals are close together, they reflect shorter wavelengths, producing colors like blue and green. When the crystals spread apart, they reflect longer wavelengths such as red, yellow, and orange. Additionally, chameleons can disperse or concentrate pigment granules inside other cells (melanophores), which affects whether their skin appears lighter or darker. This color change is controlled by a combination of hormones, temperature, the nervous system, and the chameleon's emotions, rather than simply blending into surroundings. Often, color changes serve to communicate emotions like excitement, aggression, or submission, and are influenced by environmental factors like light and temperature.