Think of your favorite color and if you’re like most people around the world, there’s a good chance it’s some shade of blue. The vast blue sky and the many blue clothes out there may trick you into thinking this color is common in the natural world but, think again. When was the last time you glimpsed a blue petal, insect or bird? They’re out there, but not many.

Blue is one of the rarest of colors in nature. Even the few animals and plants that appear blue don’t actually contain the color. These vibrant blue organisms have developed some unique features that use the physics of light.

Waves and cones

First, here’s a reminder of why we see blue or any other color.

All light is a form of electromagnetic energy, waves that can travel through a vacuum. The waves fall on a spectrum, with some having longer or shorter wavelengths. X-rays, microwaves and radio waves are all part of the spectrum, each with their own wavelength. There’s only one sliver of the spectrum that we can see, and that’s the visible light spectrum.

Zoom into the light energy and here each color also has its own wavelength. Reds and yellows have relatively long wavelengths, blues and violets have the shortest.

The color we see is the wavelength that reflects most from that object. Take a yellow sunflower, for example. It absorbs the blue, red and other color energy waves then reflects back wavelengths that appear yellow. The color receptors in our eyes then translate the flower’s wavelength into its color and send that to our brain.

Ok, back to blue.

Blue is a tough color to spot in nature because there is no naturally occurring blue compound to color things blue. This is why blue rocks and minerals are so rare and why it was so pricey back when the Egyptians began mining the vibrant blue lapis lazuli mineral thousands of years ago.

Plants are green because of the compound chlorophyll, which has a green pigment. The bright orange of carrots stems from its carotene compounds. And these pigments can go up the food chain. If you were to eat a lot – a whole lot – of carrots, your skin could take on an orange tinge.

Some animals actually rely upon their dinner for their colors. Flamingoes are born with grey feathers, for example, that gradually shift into colorful pinks from the compounds in their meals. https://www.smithsonianmag.com/science-nature/for-some-species-you-really-are-what-you-eat-40747423/

But there are shiny blue butterflies, peacocks, berries and a few other animals with rich blue hues. There’s even a bright blue tarantula. Perhaps you are thinking blueberries are everywhere and they are quite common. They are technically deep purple, not blue, and their color comes from the purple anthocyanin compound.

 

 

So how do the true blue plants, animals, and minerals get their color if there is no actual blue compound? It’s all in how these organisms are built (the external structure and for now, extend that meaning of external structure to what you can visibly see of rocks and minerals) and how light bounces off these structures – it’s actually called structural color. Light hits special structures on the cell, wing or other part of an organism that cause the wavelengths to bounce a certain way – in the very short wavelength way that results in the color blue. There are several ways this can happen and scientists are studying these blue plants and animals to understand it… https://www.gotscience.org/2016/11/nature-uses-physics-create-color-blue/

 

Perhaps that is why blue is so popular in the people world, because it is so rare in nature. But researchers have found ways to develop the color synthetically. So next time you put on your favorite blue jeans or Julianna Rae pajamas, you’ll have even more to appreciate!

Let us know what colors make you sing and if there are other colors you would like us to research!