So steeped in myth and magic are reindeer that many people grow up not realizing that they really exist. But they do! While associated with providing the deerpower for Santa’s sleigh ever since the publication of "A Visit from St. Nicholas” in 1823, reindeer have played an integral role in many Arctic cultures in Europe and Asia for millennia. But what’s their backstory? Here’s what we’ve uncovered about everybody’s favorite Yuletide ruminant.

1. Reindeer and Caribou Are the Same Thing (Maybe Kind of?)

There have been differing opinions about whether or not reindeer and caribou are one and the same. But a genetic mapping published in Nature Climate Change about the species Rangifer tarandus (which includes caribou and reindeer) shows the migration pattern of these mammals over the last 21,000 years, and claims that they are different animals — but closely related cousins. Don Moore, a wildlife biologist for the Smithsonian Conservation Biology Institute, describes reindeer as a “mostly-domesticated race of caribou.”

2. They Have Smart Feet

Since they can’t change from sandals to boots, reindeer do the next best thing. In the summer their footpads become sponge-like and provide extra traction for the soft tundra. In the winter, the pads shrink and tighten, exposing the hoof rim, which cuts into the ice and snow and allows them to dig as well.

3. Females Have Antler Power

Unique among the more than 45 species of deer, female reindeer grow antlers too, reports PBS. Males shed their antlers in early winter and females shed theirs much later, meaning that Santa’s sleigh is likely powered by a group of she-deer!

4. Antlers Have a Surprising Fate

Reindeer lose their antlers every year, resulting in a lot of shed antlers strewn across the land. But all those good antlers don’t go to waste — they are readily devoured by rodents and other animals, as they are a great source of calcium and minerals.

There's a reason that discarded antlers are hard to find. karl umbriaco/Shutterstock

5. They Have Fancy Coats

The hair that makes a reindeer’s coat is hollow, reports the San Diego Zoo. The hollow shafts allow the hairs to trap air, which provides the cozy insulation to keep the animals warm in a frigid environment.

6. They Can’t Fly, but They Can Swim

That buoyant coat also helps reindeer be excellent swimmers! They swim strongly across rough, wide rivers and icy expanses of ocean. They can swim up to six miles per hour.

7. Reindeer Can Migrate Like the Best of Them

Not all reindeer migrate, but those that do can travel farther than any other migrating terrestrial mammal. Some North American reindeer travel over 3,100 miles per year, going an average of 23 miles per day!

8. They Can See Things We Can Not

Researchers at University College London have discovered that reindeer are the only mammals that can see ultraviolet light. While our lowly old human vision allows us to only see wavelengths to around 400 nanometres, reindeer can see up to 320 nanometres, which include the spectrum we can only see with a black light. It helps them spot things more clearly in the blaring light of the Arctic.

9. They Come Out Running

Within 90 minutes of being born, a baby reindeer can run. Within a few hours, it is able to run several miles.

Reindeer calves are up and away within a few minutes of being born. V. Belov/Shutterstock

10. Babies Are Spotless

Baby reindeer don’t have spots like other baby deer do — but that doesn't make them any less adorable.

11. They Have Crazy Milk

Reindeer milk is said to be some of the richest and most nutritious milk produced by any terrestrial mammal. It has an impressive 22% butterfat and 10% protein; by comparison, cow’s milk has only 3 to 4% butterfat.

12. They Like Lichen

In fact, they live on lichen, especially Cladonia rangiferina, commonly known as reindeer moss. Given their harsh environment, they don’t have a lot of choices when it comes to grazing, so moss it is.

13. They’re Called Like Cattle

As in, they’re not referred to as bucks, does and fawns, like other deer. Rather, male reindeer are called bulls, females are called cows and babies are called calves.

14. Two of Santa’s Reindeer Had a Name Change

Reindeer became inexorably linked to Christmas in 1823 with the publication of “A Visit from Saint Nicholas” when readers were introduced to Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Dunder and Blixem. Wait, Dunder and Blixem? Indeed. But they were later changed from Dutch to German, becoming Donner and Blitzen, meaning “thunder” and “lightning.”

15. Rudolph Was Not Part of the Original Posse

Rudolph, which means “famous wolf” in German, was not introduced until 1939 when Robert L. May wrote a children’s book for Montgomery Ward titled “Rudolph the Red-Nosed Reindeer,” earning the ruby-muzzled mammal a firm place in reindeer history.