We associate certain images with Christmas: presents, crackers, Santa and his elves. The holiday season wouldn’t be complete without reindeer, as they are among the hardiest animals in nature. Able to survive in freezing temperatures, reindeer have a unique quality that sets them apart from other mammals.
They are able to see ultraviolet light and use it to find food in dark environments. On the light spectrum, ultraviolet fits between visible light and x-rays. Although it’s invisible to the human eye, we deal with it in different ways, especially where the sun is concerned. Ultraviolet light is responsible for snow blindness, in which eyes become sunburned by ultraviolet being reflected off fresh snow. The human eye becomes cloudy in the process of blocking UV light and it can be very painful. Reindeer don’t have this problem.
As reindeer are surrounded by snow for most of the year, it makes sense they would have developed a way to use UV light to their advantage. The deer have an effective method of night vision, as certain things absorb UV and contrast strongly with snow. This includes lichen, a major food source for the deer, which appears black in the spectrum. Urine and fur can also be detected as signs of predators. This allows deer to see wolves who are camoflagued to other animals who can’t see in UV.
This raises questions as to how reindeer can protect themselves against UV. It may have something to do with the specific structure of their eyes. There is potential for furthur study, as scientists could develop new strategies to prevent UV damage in humans. It goes to show that reindeer are more interesting than they first appear. Perhaps it wasn’t Rudolph’s shining red nose that helped Santa get through the snow on Christmas. But the collective effort of all his deer pulling together to see in the darkness.