Few animals are as famous for camouflage as chameleons, whose color-changing skills have made them icons of adaptability. But that probably wasn't the reason they evolved the ability — instead, scientists think they mainly change colors to communicate.
Certain hues signal certain moods: Some advertise anger, others mean "I'm ready to mate!" And while this color code may be why chameleons evolved shifty skin, many have clearly seen its value as camo, too. Some even target specific predators — one species in South Africa blends in with the ground to avoid [skipwords]birds[/skipwords], but blends in with the sky to avoid snakes. The key is the chromatophore, a type of pigmented cell layered underneath chameleons' transparent outer skin.