By: By Michele Berger
Reindeer are exposed to darkness for months at a time. Researchers have now discovered how the animals’ eyes adjust. (Erling Nordøy)
Scientists in 2011 discovered that reindeer have a built-in AC system to keep from overheating in their natural fur coats. Recently, researchers found these mammals also have a unique way of coping with extremely dark Arctic winters: Their eyes change color.
During the sunny time in their habitat, reindeer have yellowish-gold eyes, but during the cold season, the eyes turn a noticeable hue of blue, a new study published in the Proceedings of the Royal Society Breported.
It’s because of changes in a light-reflecting tissue layer behind the retina, according to Science. “This structure, called the tapetum lucidum (Latin for ‘bright tapestry’), gives the eye’s light-sensitive neurons a second chance to detect scarce photons in low-light conditions. (The layer also produces the ‘eye shine’ that can make animal eyes appear to glow in the dark.)” In other words, it makes the eyes extremely sensitive to light.
Reindeer eyes change from gold (right) in summer to blue (left) in winter. (University College London)