Did you know that blue is the rarest colour in nature compared to other colours? Even the biggest sea mammal ( the blue whale) weighing up to 140,000kg with a heart the size of a car, is not that blue. They are more of greyish blue even though they appear to be bluer due to the colour of the water.
But isn't the Maltese Tiger blue shown below? Well, it depends on the side of the fence you are in as some still do not believe it ever existed.
Wikipedia Creative Common A Blue Maltese Tiger
In the story of Harry R. Caldwell, a Methodist Missionary in China in 1924 published a book about a blue-morph tiger in the book Blue Tiger.
Again the cook tugged at my elbow, saying, “Tiger, surely a tiger,” and I once more looked at the object, this time to see what I thought was a man still upon his knees in the trail. I was about to turn again toward the goat when my cook excitedly said, “Look, look, it is a tiger,” and, turning, saw the great beast lengthen out and move cautiously along the trail a couple of rods and then come to a sitting position near a clump of grass. Now focusing upon what I had altogether overlooked in my previous hurried glances, I saw the huge head of the tiger above the blue which had appeared to me to be the clothes of a man. What I had been looking at was the chest and belly of the beast…The markings of the animal were marvellously beautiful. The ground colour seemed to be a deep shade of Maltese, changing into almost deep blue on the underparts. The stripes were well defined, and so far as I was able to make out similar to those on a tiger of the regular type."Blue Tiger Pg 70
Many people are sceptical about this tale, but some cryptid advocates have theories on how such a blue-coloured tiger could be true. This claim is based on a gene in the makeup of tiger that is called agouti gene. A team of Harvard scientists discovered that it is responsible for colours in deer mice. It is also the cause of pigmentation in cats, dogs, and horse's pigmentation in the ears, lower legs, etc.
This agouti gene in mice causes the change in pigmentation from brown or black to orange or yellow pigments due to its signalling of peptide. The peptide brings the melanocytes, the melanin-producing cells under the skin's epidermis, into action.
Domesticated cat has a gene dilution that produces a greyish and sometimes bluish colour in cats. So the cryptids figured the Maltese Tiger might have a combination of dilution gene and agouti gene to create a blue tiger. Well, it would be nice to see one as the picture you see above, and others could just as well be photoshopped according to hoax-slayer website.
Plants on the other hand do not have much problem with producing blue pigments due to anthocyanins. Anthocyanins are naturally occuring plant pigments that imparts colours to flowers and plants.
But even this blue orchids do not come naturally to the orchids as the breeders use dye to change its colour from white to blue.
The retired Professor of Biological Sciences at Florida University Miami in the USA, David Lee, the author of "Nature’s Palette: The Science of Plant Color" has this to say about plant and blue colour.
Blue is a colour that is infrequent in nature. Less than 10 percent of the 280,000 species of flowering plants produce blue flowers.
But in the animals, the blue colours are commonly from how the light acts on it; absorption, selective reflection, and iridescence. Irridescence is that phenomenon of colour change due to the angle of view and light illumination. For instance, a soap bubble tends to change colour dependent on the angle of lighting.
The animals like the little bluejay bird technically produce only melanin. But due to selective light scattering from tiny sacs in its feathers, it absorbs all colours and reflects the blue colour which the eye sees. This scattering of blue light more strongly than other rays is known as Rayleigh scattering. It is the reason the sky is blue.
Why the Sky is Blue
With a little help from physics, we may just kill two birds with one stone (pun was intended). The Rayleigh scattering is the reason the sky is blue. The same scattering makes the melanin-producing birds like blue jay with special sacs in their feather to do a selective reflection of light to appear blue to the eyes.
We already know the Sunlight is a composite of colours, and it shines through the air molecules to get to us. But as it travels the tiny molecules of air scatters it, but blue light receives a stronger scattering due to it having the shortest wavelength (450 nanometer) than the other longer wavelength composite of the visible light (reds, etc.). That makes the sky appear blue.
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Wikipedia Creative Common: How Eye Get its Colour
Even the human eye colour is not left out in this reflection business. The pigmentation of the iris and the scattering of the light by the melanin in the iris gives the eye it's blue colour.
It is interesting to note that there is no green or blue pigments in the human iris. It is all about light and reflection.
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