You might think blue is everywhere; it’s the color of the oceans and the sky; look further than that, and you will realize that blue isn’t very common in living things.
The world's most favorite color is blue. This color has delighted and intrigued artists and scientists alike for centuries and is a number-one choice for everything from house paint to the jeans you're probably wearing this very minute. Yet it turns out the color is surprisingly hard to come by in nature. So, let us find out why blue is so rare in nature.
Shorter wavelength and cones
All light is a form of electromagnetic energy or waves that can travel through a vacuum. The waves fall on a spectrum, with some having longer or shorter wavelengths. Zoom into the light energy and you’ll find every color having its own wavelength. Red and yellow have relatively long wavelengths, while blue and violet have the shortest. The color that we see is the wavelength that reflects most from that object. For instance, take a yellow sunflower. It absorbs the blue, red, and other color energy waves then reflect 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.
Absence of blue biological pigment in animals
The color of an animal’s fur, skin, or feathers typically comes from pigments or chemicals that absorb specific wavelengths of light and others' reflections. Animals obtain these pigments from the food they consume. However, natural blue pigments are almost nonexistent. The phrase “truly blue” refers to animals with blue pigmentation, as most blue animals derive their blueness not from pigments, but from the structures of the molecules on their body and how they reflect light. In the case of the blue jay, its feathers have a specific bead design that scatters light in a way in which only blue light can escape, making the bird appear blue.
Absence of blue biological pigment in blue morpho butterflies
As for the blue morpho butterfly, the ridges in its scales cause the butterfly to look blue due to constructive interference. When light hits the ridges of the scales, some light reflects off the top layer, and the rest goes deeper into branches of the ridges, some of which also gets reflected off the branch’s bottom layer, resulting in two rays of light. Like many blue animals, the structural blue color is created using optical effects, such as interference, rather than biological pigments.
How do most blue flowers get their color?
Blue flowers usually get their blue coloring from modifying the red pigment anthocyanin through shifting the pH, mixing it with other pigments, or adding on molecules and ions to change the color of anthocyanin. Through pH shifts and the mixing of pigments, combined with the reflection of natural light, the plants are able to generate the appearance of a naturally occurring blue hue. That is the reason why plants such as hydrangeas, bluebells, and morning glories appear to be in various shades of blue, when in fact, there is no true blue pigment in plants.
The rarity of blue in nature is perhaps the reason why people love the color so much.
