Nature entails species that have a wide spectrum of colors, ranging from the olive- colored Ridley turtles, to pink flamingos, to the red-billed firefinch. But what about the color blue?
Well, blue is an extreme rarity when it comes to the animal kingdom. Although we may find blue butterflies and blue whales, they are actually not blue. These species merely seem blue.
Most animal/bird species around the globe lack the pigment needed for them to look blue. But if they lack the pigment, which is a prerequisite for any color to be visible, then how are they still blue?
Well, this is a question that had baffled scientists for decades. After much research and analysis, they found the answer to this macrocosmic question in the microcosm of the cells.
The Science behind it
Instead of containing the blue pigment, the species that “appear” blue, consist of unique cell structures at the microscopic level. We already know that different colors exhibit different wavelengths. In the VIBGYOR spectrum, the color violet has the shortest wavelength when compared to the color red.
So, when different colors come in contact with these cells, their unique structure results in various colors bouncing off, but in a haphazard manner. However, the color blue, with its short wavelength, bounces off symmetrically upon hitting the cell. It is due to this selective reflection that blue is visible to us. This phenomenon is known as structural coloration.
This phenomenon hit headlines yet again when the Indian state of Maharashtra declared Blue Mormon Butterfly as the state butterfly in 2015. Its scientific name is Papilio Polymnestor. With black wings with vibrant blue streaks, it is the second largest butterfly of India.
The Human Connection
It is also because of this phenomenon that some human beings have blue irises. The color palette in humans ranges from brown to black, depending on the melanin concentration in the iris. Thus, colors like silver, hazel, blue, green, etc. are merely a result of the structural coloring of the iris.
Well, it looks like our vision has been fooling us all along, hasn’t it?