Color me green, or gray, or brown…

Last month, in a post about the green anole, I mentioned that it was able to change color. Anoles and chameleons are not the only color-changing animals. If you’ve ever caught a frog outdoors in cold weather and it seemed to get lighter as it warmed up in your hands, that wasn’t your imagination.

Backyard Biology has a fantastic explanation of frog skin colors and how they can change.

Back Yard Biology

Gray Treefrog, Hyla versicolor The ever-changeable, Gray Treefrog.  How does it do it?

Green is a popular color for frogs, and birds too, but that lovely green color doesn’t come from a green pigment as you might expect, but from the interaction of multiple layers of specialized color and light-reflecting cells in the upper layers of their skin.

Frogs have three layers of chromatophores (color-producing cells) in their skin. The deepest layer are melanophores that produce melanin pigment giving skin a brown to black color. The middle layer are iridiphores which contain no pigment but instead have mirror like plates capable of producing iridescence, or when viewed from a certain angle, reflect blue light. The most superficial layer of chromatophores are xanthophores that contain a yellow pigment.  When the middle layer of iridophores interact with the top layer of yellow-pigment containing xanthophores, you get what elementary school students have learned:  yellow paint + blue paint…

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Bethany Harvey

I’m a biologist, GIS nerd, and occasional wildland firefighter living in North Carolina. The many hobbies I enjoy but am bad at include photography, rock climbing, tabletop RPGs, knitting, and orienteering. I write literary short stories and SFF novels, and hope to someday figure out why it doesn’t work the other way around. You can find me yelling about politics, gaming, and writing on Twitter (@bethanyharvey) or about under-appreciated wildlife at OverlookedNature.com.