The Science Behind Reindeer's Color-Changing Eyes
A reindeer in Sweden Look Sharp! via Wikimedia Commons Winter in the Arctic is grim—day and night blur together for 24 hour stints without sunlight. Reindeer manage to survive these gloomy weeks thanks to a peculiar adaptation. As the days grow darker, reindeer's eyes turn from gold to blue. A study published earlier this year in the Proceedings of the Royal Society B journal explained the science behind reindeers' changing eyes. The color change happens in the tepetum lucid, which is the layer of tissue in the eye that reflects visible light back through the retina. This is the same component of the eye that makes cats' and dogs' eyes seem to glow in the dark. In the summer when days and nights are marked by nearly constant brightness, the eye tissue is tinged gold, which is common for ungulates such as...