London: Scientists have discovered that reindeer eyes changes colour from gold to blue over the course of the year.
The study revealed that the reindeer is uniquely adapted to Arctic winters.
The study found that like many other mammals, during the bright summers reindeers` eyes reflect back most light through the retina - so they seem to be gold coloured.
The research showed that a kind of enhanced night vision kicks in through winter, however, when a layer of tissue behind the retina becomes less reflective and seems to be blue coloured, the Independent reported.
Lead researcher Professor Glen Jeffery said that this gives them an advantage when it comes to spotting predators that could save their lives.
He said that by changing the colour of the TL in the eye, reindeers have flexibility to cope better with extreme differences between light levels in their habitat between seasons.
The study was conducted by Professor Jeffery and his colleagues at University College London, in collaboration with the University of Tromso in Norway.
The researchers suggested that the colour change could be caused by pressure within the eyes. In winter their pupils exist in a permanent state of dilation that prevents fluid in the eyeball from draining naturally.
They said that the pressure compresses the tissue behind the retina, reducing the space between collagen in the tissue and therefore reflecting the shorter wavelengths of the blue light common in Arctic winters.