It is a question that has long puzzled scientists – why are tigers exactly orange?
One might think that it makes them more striking – especially against a green leafy background.
William Blake summarized it in his famous poem that generations of schoolchildren know: & # 39; Tyger, tyger, burning brightly / In the forest of the night. & # 39; But now the answer is near.
Although striking to us, computer simulations of what the big cats see of the main animals they hunt, deer, show a different image.
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One might think that it makes them more striking – especially against a green leafy background (stock image)
WHAT ANIMALS ARE COLOR BLIND?
The study that simulates which colors prey of the tiger see when they look at the predator found that animals such as deer are essentially red-green color-blind, like some people.
This means that they only pick up greens and blues and no oranges and reds.
This means that they are more sensitive to the blue-green part of the spectrum (due to the high stem density of their eyes) and less sensitive to light with long wavelengths (orange and red).
That is why the tiger appears green to deers instead of orange, which helps their camouflage effect.
Other animals that are red green & # 39; color blind & # 39; are: wolves, coyotes, foxes, bulls, dogs and cats
People with normal color vision can see red, blue and green colors.
But deer can only pick up blue and green light, they are effectively color blind to the color red, like some people.
It means that the orange color of the tigers looks green, which means they can be perfectly integrated into the background, according to new research claims.
Dr. John Fennell from the University of Bristol and colleagues said they were using computers to estimate how detectable a particular animal was.
They did this by using images of the environment in which the animal lives and then generating images to see if the camouflage helps the animal to work on.
Dr. Fennell writes that by simulating what the world looks like for animals that & # 39; dichromats & # 39; are – who cannot detect the difference between red and green – & we also identify the optimal colors for camouflage and visibility & # 39 ;.
Dr. Fennell writes in the Royal Society Journal Interface: & Consider the cloak of a tiger (Felis Tigris); it has a fur that looks orange like a trichromat observer rather than a little green, although the latter should be a better camouflage for an ambush hunter in forests.
& # 39; However, as shown, the color of the tiger when considered a dichromat is very effective & # 39 ;.
Dr. Fennell tested the theory of people by examining images in which a red object was inserted in two backgrounds.
One was from temperate forest – for which photos of Leigh Woods in North Somerset, and semi-arid conditions, in the Tabernas desert in Almeria in Spain.
Researchers measured how quickly the observers detected the sphere against any background in images that were reproduced to simulate three-color view and two color images.
Although striking to us, computer simulations of what the big cats see of the most important animals they hunt, deer, show a different image (stock image)
In both scenarios, observers were much faster at detecting the three-color images.
The question then arises why tigers don't grow green coats.
Dr. Fennell and colleagues write that mammals cannot produce green fur.
To do this, & # 39; a significant change in the biochemistry of mammals & # 39; are required.
There is only one mammal that is known to have green fur – and this is achieved by what can be considered, well, cheating.
A kind of sloth looks green when green algae grow.
The orange color in the fur of a tiger is produced by a chemical called pheomelanin.
Dr. Fennell writes that there is still an & # 39; open question & # 39; is – why deer have never developed a trichromatic vision – because this could help them stop being eaten.
Aside from this, Dr. Fennell and colleagues ask the wartime claim that color-blind people can spot camouflaged enemies better than people with normal color vision.
This has not been replicated in laboratory tests, Dr. added. Fennell ready.
In general, having a tri-color view is more effective in breaking through & # 39; camouflage & # 39 ;, he said.
The research did not take into account the role of the dark stripes of the tiger that help break their silhouette, which is effective regardless of the kind of vision that a spectator has.
How orange tigers vary in the wild.
The extinct Balinese tiger had a very dark deep-set, which might make it difficult to find a color-blind prey, but this could mean that people had it easier to spot.
Bengal tigers are usually redder, while the Amur tiger is more golden than orange.
Tigers in northern regions such as Russia and northern China usually have lighter coats, while southern tigers found in Malaysia and Sumatra are usually darker.
There have been reports of tigers without stripes – in the 1960s and until late in 1988 – but they have never been taken. About 1 in 10,000 tigers – & # 39; melanistic & # 39; called – are born white.
Strangely enough, white tigers are often cross-eyed due to a genetic defect.
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