Reindeer See Ultraviolet Light
Posted by Ryan on May 27th, 2011
Reindeer have developed the ability to see the world in ultraviolet light since migrating to the Arctic 10,000 years-ago. Most mammals, aside from rodents and some species of bats, can only see the visible spectrum and the shorter wavelength ultraviolet light remains invisible. Also, aside from being unable to see ultraviolet light, it is also damaging to most eyes, causing snow blindness.
In dark conditions, they shone LED lights of different wavelengths, including UV, into the eyes of 18 anaesthetised reindeers while recording with an electrode whether nerves in the eye fired, indicating that the light had been seen. The UV light triggered a response in the eyes of all the reindeer.
The eyes of most mammals cannot cope with UV light because it carries enough energy to destroy their sensitive photoreceptors, permanently damaging vision. To prevent this happening we experience “snow blindness”: our corneas respond to UV light by becoming temporarily cloudy, preventing excess amounts of UV reaching and burning the retina.
“Why don’t reindeer, arctic fox, polar bears or arctic seals get snow blindness?” asks Jeffery. “Arctic mammals must have a completely different mechanism for protecting their retinas.”
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