Why are Tigers orange?

The colours and patterns of an animal serve lots of different purposes — for instance, to help them stand out to mates or even to warn predators that they're toxic. But for ambush predators like tigers, the ability to remain invisible to their prey determines whether they catch dinner or go hungry. So, of all the colours they could be, why are tigers orange?

16….. To our eyes, orange stands out in most environments, which makes tigers relatively easy to spot.

But that's because we have what's called trichromatic colour vision. When light from the outside world enters the eye, it hits a thin layer in the back called the retina. 17….. Rods only sense differences in light and darkness, not colour, and they're used mostly in dim light. Cones are what we use for colour perception, and most humans have three types: cones for blue, green and red. That's why our vision is called trichromatic: We can see three primary colours and their colourful combinations. We share this style of vision with apes and some monkeys.

18….. That means their retinas contain cones for only two colours: blue and green. Humans who get information only from their blue and green cones are considered colour-blind, and can't distinguish between red and green shades. The same is likely true for dichromatic animals.

Terrestrial mammals like deer are the tiger's main prey, and their dichromatic vision means they don't see the predator as orange — they see it as green. That makes the tiger much harder to spot as it's prowling behind a bush or crouching in the grass. 19…..

In essence, it is easier to produce browns and oranges because of the biomolecular structure of the makeup of the animal than it is to produce green. 20…. That's an alga that grows in its fur. And as far as I'm aware, there are no green furry animals.

But considering that evolution tends to favour traits that help a species survive, why wouldn't prey animals have evolved the ability to see orange?

You would imagine that in an evolutionary arms race, an improvement in visual perception would provide the prey with better visual systems in the first instance. But there seems to be no evolutionary pressure, particularly for deer, which are the main prey of the tiger, to become trichromatic. 21…..

So the evolutionary arms race really doesn't exist for that colour, as such, it's just that the tiger has evolved over the sweep of evolution to have a colouring, a camouflage system, which protects it very well in its jungle setting.