Throughout the year, reindeer’s eyes change from gold to blue to help the animals see better as the light levels change.
Researchers from University College London have discovered that arctic reindeer have a modification that allows their eyes to reflect more or less light depending on the time of year. This is a unique variant and the first time it has been found in a mammal.
Watch the video to learn the science behind the changing colors of reindeer’s eyes.
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Due to the extreme changes in sunlight in the Arctic Circle, reindeer spend three months of summer in constant light and three months of winter in total darkness. To help the reindeer see better, their eyes turn from gold in the summer to blue in the winter. The blue eyes reflect less light, which increases the sensitivity of the reindeer’s eyes and allows them to see better in the dark.
This change occurs in the tapetum lucidum, a layer of tissue found at the back of the eyes of some animals. This tissue reflects certain light waves, and is what causes the eye shine common in deer, cats and raccoons.
Researchers believe discovering the change that occurs in the tapetum lucidum supports their belief that Arctic reindeer can see ultraviolet light, which the human eye is not able to see. By seeing ultraviolet waves, reindeer are more likely to find food and see predators.