Amethyst starling Cinnyricinclus leucogaster The striking purple on these birds is caused by a combination of pigmentation and structural color. The pigment is melanin, producing varying reddish colors; the structural element is the refraction of blue light scattered by the structure of the feathers. Red and blue together make purple. This is a shimmering, shifting purple, though—the blue light is refracting off many different angles, which creates iridescence.
Blue morpho butterfly Morpho peleides Butterfly wings are made up of thousands of tiny scales—and most are colorless. It’s the way that light hits their many surfaces that creates the color we see—in this case, mostly blue light, refracting from many angles to create what our eyes see as shining, shimmering blues.
Great blue heron Ardea herodias As with other birds, the blues in this heron’s feathers are the result of blue light bouncing off the structure of the feathers. The different shades are created by differing amounts of other melanin pigments in the feathers.
Cheetah Acinonyx jubatus In mammals, melanin is the pigment that gives skin and hair their color, contained in pigment cells called melanocytes. However, there are two types of melanin in mammals: eumelanin, which produces browns and blacks, and pheomelanin, which produces yellows and reds. The cheetah’s black spots contain mostly eumelanin. Its golden fur has little eumelanin; but it only has some pheomelanin—more, and cheetahs would be orange or red! Genetics determines how the spot pattern will be laid out.
Thick-billed parrot Rhynchopsitta pachyrhyncha These parrots are this shade of green because of a combination of factors. First, melanin in the cells of their feathers produces a reddishbrown color. Second, they eat plants containing carotenoids, which are pigments that produce yellow colors, that are deposited in the feather cells. And third, blue light reflects off the feathers. It’s the interaction of all three that results in the green we see.
Emerald tree boa Corallus caninus Amphibians and reptiles have pigment-bearing cells in their skin called chromatophores, composed of three layers. The bottom layer contains the dark pigment melanin; the middle layer is colorless but reflects light wavelengths; and the top layer contains yellow/red pigment. When light hits the cells of this boa, most of the colors are absorbed, except for blue. It hits the middle layer and bounces back through the top layer. The combination of blue light plus yellow pigment means we see a green snake.
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