This is the olivewing butterfly. It’s one of very few insect species on Earth known to have a true blue pigment. This is a blue poison dart frog, one of the only vertebrates known to contain blue pigment. No matter how you look at them, they’re blue. No matter how you look at them, they’re blue.





All of the other animals only appear blue. You may perceive blue, but it’s because these animals have all evolved a way to trick your eyes using the physics of light to control what you see.

What’s happening when our eyes see structural colors like the blue of a peacock feather, a beatle’s elytra, or a blue morpho wing? And why is blue pigment so rare in nature? This Explorer clip from National Geographic summarizes the science behind what you’re really seeing when you see a blue animal.

Related listening from NPR: How Animals Hacked The Rainbow And Got Stumped On Blue.



Also: Pollia condensata.

Plus, watch related videos: Go inside an ice cave to see nature’s most beautiful blue, What Gives the Morpho Butterfly Its Magnificent Blue? And why is the sun yellow and the sky blue?

Plus: In Search of Forgotten Colours – Sachio Yoshioka and the Art of Natural Dyeing.