Duh, except for the sky… and the ocean… Don't miss our next video! SUBSCRIBE! ►► http://bit.ly/iotbs_sub ↓↓↓ More info and sources below ↓↓↓ 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. And the ones that do make blue? They make it in some very strange and special ways compared to other colors. In this video, we'll look at some very cool butterflies to help us learn how living things make blue, and why this beautiful hue is so rare in nature. SPECIAL THANKS: Smithsonian Institution - National Museum of Natural History Bob Robbins, Ph.D. - Curator of Lepidoptera Juan Pablo Hurtado Padilla - Microscope Educator Richard Prum, Ph.D. - Yale University Vinothan Manoharan, Ph.D. - Harvard University SOURCES: Bagnara, J. T., Fernandez, P. J., & Fujii, R. (2007). On the blue coloration of vertebrates. Pigment Cell & Melanoma Research, 20(1), 14-26. Cuthill, I. C., Allen, W. L., Arbuckle, K., Caspers, B., Chaplin, G., Hauber, M. E., ... & Mappes, J. (2017). The biology of color. Science, 357(6350), eaan0221. Kinoshita, S., Yoshioka, S., & Miyazaki, J. (2008). Physics of structural colors. Reports on Progress in Physics, 71(7), 076401. Kinoshita, S. (2008). Structural colors in the realm of nature. World Scientific. Prum, R. O., Quinn, T., & Torres, R. H. (2006). Anatomically diverse butterfly scales all produce structural colours by coherent scattering. Journal of Experimental Biology, 209(4), 748-765. Vukusic, P., & Sambles, J. R. (2003). Photonic structures in biology. Nature, 424(6950), 852-855. Vukusic, P., Sambles, J. R., Lawrence, C. R., & Wootton, R. J. (1999). Quantified interference and diffraction in single Morpho butterfly scales. Proceedings of the Royal Society of London B: Biological Sciences, 266(1427), 1403-1411. ----------- FOLLOW US: Merch: null Facebook: http://www.facebook.com/itsokaytobesmart Twitter:@DrJoeHanson @okaytobesmart Tumblr: http://www.itsokaytobesmart.com/ Instagram: @DrJoeHanson ----------- It's Okay To Be Smart is hosted by Joe Hanson, Ph.D. Director: Joe Nicolosi Writer: Joe Hanson, Ph.D. Producer/editor/animator: Jordan Husmann Producer: Stephanie Noone and Amanda Fox Produced by PBS Digital Studios Music via APM