Among living things, the color blue is oddly rare. Blue rocks, blue sky, blue water, sure. But blue animals? They are few and far between. In this video, we'll look at some very cool butterflies with Bob Robbins, Ph.D. from Smithsonian's National Museum of Natural History to help us learn how living things make blue, and why this beautiful hue is so rare in nature.

Originally released by Knowledgemotion, 2018. Streaming video file encoded with permission for digital streaming by Infobase on February 21, 2020.

Why Is Blue So Rare In Nature? (7:39); .