You might know that it has something to do with camouflage, but how? Their bright orange color doesn’t really blend in with their green forest environment.

A tigers diet mostly consists of Sambar deer, Spotted deer, Elk, Wild boars, and in some regions, larger pray such as Indian bison and banteng. What all these animals have in common are that they are all dichromats. Meaning that that they only have two color cones in their eyes. In this case only blue and green cones. (Humans, on the other hand, have blue, green, and red cones, making us trichromatic.) Because they don’t have a red cone that makes them essentially red-green color blind. Making them unable to perceive the difference between red and green. So, a tigers color appears green to them (or at least their version of green).

But why aren’t tigers just green in the first place?

Wouldn’t that be better? So they could also fool the trichromats? Well, tigers are mammals and therefore can not make green pigments. A mammals color is almost exclusively determined by melanin. And melanin can only make shades of black, brown, yellow and red.

What about people with green eyes?

If mammals can’t make green pigments, then how do some people have green eyes? Well, first we have to talk about blue eyes.Blue eyes are the result of low melanin and Rayleigh light scattering. When light enters an iris (the colored ring of your eye) with low melanin, the stroma’s (the middle layer and thickest part of the cornea) collagen fibers scatter the blue wavelengths back. Causing the Iris to look blue because there is too little pigment to obstruct the blue wavelengths. 

Ok, so how do green eyes work?