So why is brown (which is essentially a shade, or rather a collection of shades, of orange) so common? Why is absorbing blue and nothing else so much easier?
How do you mean rare?
“I often wonder why there’s no blue food. Every other color in well represented in the food kingdom. And don’t bother me with blueberries; they’re purple. The same is true with blue corn and blue potatoes. They’re purple. Blue cheese? Nice try. It’s actually white cheese with blue mold. Occasionally, you might run across some blue Jell-o in a cafeteria. Don’t eat it. It wasn’t supposed to be blue! Something went wrong.”
Blossoms?
Bollocks it’s rare! Blue is THE MOST COMMON COLOR for flowers on the planet. Talk to any florist and they’ll bemoan the profusion of blues and violets and purples in petals, and the relative lack of other colors in nature.
The correct title of the post should perhaps be “why is blue so rare in the ANIMAL KINGDOM?” In nature as a whole, it’s pretty darn common.
There are lots of pigments and dyes so it is hard to give a completely general answer. But here are two simplified ones…
Blue photons have about twice the energy of red photons. It is easy to imagine some process where a blue photon has enough energy to move an electron’s energy level from one band to another, perhaps with some energy left over; while a red photon does not. So the blue photon gets absorbed and the red one does not. You can make green and blue by having something where the photons are absorbed if the energy falls within a band, but this is harder, particularly if you want a sharp cut-off to the high energy passband.
Blue photons have a photon energy that is similar to many of the bond energies of organic materials. This means blue, and more particularly UV photons can damage organic compounds. So, when you dump the energy of a blue photon, an organic compound has to have a way to dump this energy without breaking bonds. There are less organic compounds that can do this, but if you find one, then it is probably less prone to fading. Most CMY prints left in the sun will fade in the yellow first, and in the cyan last.
bFlowers?
i think of tropical fish and poison dart frogs with bright blue coloring
I was joking. Sorry about that.
Lots of birds have blue eggs, and it’s not a structural colour- it’s from biliverdin.
Starlings alone must produce nearly a billion blue eggs every year:
http://1.bp.blogspot.com/-OYuJC1Yzapk/VaEsNuSzqsI/AAAAAAAABsA/rvUcsePJ2qg/s1600/81oYx2dS2gL.SL1500.jpg
Speaking of ‘blue’ and ‘eyes’, some “shiners” can also be blue in appearance.
