Reindeer eyes change color — they’re golden in summer and blue in winter.
Rudolph’s nose may have been red, but his eyes were blue — except in the summer, when they would have been golden. That’s because reindeer eyes change color depending on the time of year, which helps them see better in different light levels. Their blue eyes are approximately 1,000 times more sensitive to light than their golden counterparts, a crucial adaptation in the dark days of winter. Only one part changes color, however: the tapetum lucidum, a mirrored layer situated behind the retina. Cats have it, too — it's why their eyes appear to glow in the dark. This part of the reindeer retina shines a different hue depending on the season.
Rudolph and his eight friends aren’t the only animals with unique eyes. Chameleons can move theirs independently of one another, giving them nearly 360-degree views of their surroundings; goats' distinctive regular pupils give them a panoramic view of the horizon, allowing them to detect predators early; and cuttlefish pupils resemble a "W" in bright light and a circle in the darkness of deep waters — to name just a few unusual animal peepers. Maybe those critters should get songs written about them, too.
Long before he made his television debut, Rudolph graced the pages of a coloring book handed out to children visiting Santa Claus at Montgomery Ward department stores. Catalog copywriter Robert L. May was commissioned to create a memorable character for those books in 1939, and his creation was wildly successful — 2.4 million copies were given out the first year alone. This was despite the fact that May’s boss initially disliked Rudolph’s red nose because it could imply that the animal had been drinking. Rudolph was a household name within a decade, with the song we all know and love (which happens to have been written by May’s brother-in-law) topping the charts around Christmas 1949. He really did go down in history.
