Why Aren't Tigers Green or Brown?
There are few sights more striking than a tiger with its brilliant orange coloring. But does their coloring put them at a disadvantage when hunting?
STORY AT-A-GLANCE
Predators, such as tigers, would seem to be at a great disadvantage due to their brightly colored fur
However, most terrestrial mammals, including dogs and deer — tigers’ favorite prey — have dichromatic vision, which means they have two color receptors that perceive wavelengths of light that correspond to blue and yellow
Tigers’ prey can see color in combinations of blue and yellow, so to a deer, a tiger appears green — the perfect color to blend in with the grass behind them
In the wild, animals are often uniquely adapted to blend in with their environments, so they can easily camouflage themselves against their forest, desert, jungle or other habitat. There are exceptions, of course, like poison tree frogs, which sport bright yellows, blues and oranges to warn predators that they’re toxic.
However, predators, such as tigers, would seem to be at a great disadvantage due to their brightly colored fur, which makes them stand out to their potential dinners. Why, then, are tigers bright orange? It has to do with vision.
Color-Blind Animals Can’t See Orange
Humans are able to marvel at the beauty of a tiger’s orange fur courtesy of trichromatic color vision. Most humans, except those who are color blind, have three color receptors, or cones, in their eyes, which allow them to see blue, green and red — and all of the color combinations they create.
Most terrestrial mammals, including dogs and deer — tigers’ favorite prey — have dichromatic vision, which means they have two color receptors that perceive wavelengths of light that correspond to blue and yellow. This means tigers’ prey can see color in combinations of blue and yellow. To a deer, a crouching tiger appears not orange but green — the perfect color to blend in with the grass behind them.1
Why Aren’t Tigers Green?
If green is the perfect color for tigers to conceal themselves in a forest, then why aren’t they green instead of orange?
The answer, again, depends largely on the visual system of the prey. In a study published in the Journal of the Royal Society Interface, researchers used image processing techniques to simulate how a tiger appears while walking in a forest to a being with dichromatic or trichromatic vision.2 For an animal with dichromat vision, the tiger quickly becomes camouflaged against the lush, green background.
“Consider the coat of a tiger (Panthera tigris),” the researchers wrote. “It has fur that appears orange to a trichromat observer rather than some shade of green, though the latter should be more appropriate camouflage for an ambush hunter in forests. However, as illustrated … when viewed as a dichromat, the tiger's color is very effective.”3
Further, there are no animals with green fur in nature; while sloths may appear to have a green tinge, this is due to green algae that grows in its fur. Study author John Fennell with Bristol Veterinary School in the U.K. explained in a news release, "In essence, it is easier to produce browns and oranges because of the biomolecular structure of the makeup of the animal … And as far as I'm aware, there are no green furry animals."4
There is little reason, it seems, for predators to turn green, given their effective camouflaging when viewed by their dichromatic prey. As the researchers explained:5
“Based on our results and given that most non-human mammals have dichromatic color vision that is unable to reliably differentiate orange and green, it seems that there is little benefit to actually become green if the receiver is dichromat.
Hence predators (e.g. tigers), whose main prey is other mammals (e.g. deer), experience little evolutionary pressure to evolve green coloration from a trichromatic perspective. Deer are dichromats and, for them, most of their predators, like tigers, appear green.
… For species seeking concealment from dichromats there appears to be little pressure to actually become green. In contrast, when hiding from trichromats, simple coloration is not that effective. The open question is therefore not why predators are not green, but why their major prey are not trichromats.”
As for why prey animals haven’t evolved to see orange the way humans do, such that an orange tiger would stand out in the forest like a traffic cone, Fennell said:6
"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. That's probably because the tiger doesn't know it's orange either because it, too, is a dichromat.”
Tigers Share 95.6% of Their DNA With Housecats
If your stealthy housecat has ever struck you as being similar to a wild tiger, it’s because they are. Siberian tigers share 95.6% of their DNA with housecats, and it’s believed the two diverged about 10.8 million years ago.7 Tigers also share the familiar tabby cat pattern. Tabby refers to a color pattern that consists of regularly spaced dark markings on a lighter fur background.
Not only is this apparent on most domestic cats, with a wide variation in form and color, but also on many wild cats, including tigers. In fact, it’s believed that domestic tabbies get their stripes from their ancestor, the striped Near Eastern wildcat.8 The tiger’s striped coat adds yet another layer of camouflage, helping them to blend into foliage while stalking their prey.9
Healthypets Disclaimer: This information is for educational purposes only and is not intended to replace the advice of your own veterinarian or doctor. Dr. Karen Becker cannot answer specific questions about your pet's medical issues or make medical recommendations for your pet without first establishing a veterinarian-client-patient relationship. Your pet's medical protocol should be given by your holistic veterinarian.