Why Is Rudolph's Nose Red?

By: John Fuller  | 

Rudolph the red-nose reindeer
We know Rudolph has a glowing red nose, but could bioluminescence be the reason behind his ruby muzzle? CBS

It's no wonder Rudolph the red-nosed reindeer is the most famous member of Santa's team. In addition to being a skilled flyer, his nose — as his name suggests — glows bright red. This unusual variation on the reindeer nasal prominence has all kinds of benefits, the most important, of course, involves guiding Santa's sleigh.

According to folklore, if the weather's ever bad on Christmas Eve, Santa's cleared for flight — by the Federal Aviation Administration, for that matter — thanks to the brightness of Rudolph's nose.

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But how does Rudolph's nose actually work? How can one reindeer create a light bright enough to lead a sleigh through darkness and inclement weather? And how can a reindeer even have a glowing red nose?

Although no one may ever know for sure just how Rudolph got his unusual nose, we think the most logical explanation for how the doe-eyed deer guides Santa's sleigh is of course, science. Stick with us as we explore several scientific explanations behind Rudolph's bright beacon.

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Rudolph's Bioluminescence

Rudolph the red-nose reindeer
Rudolph could use bioluminescence to locate a safe route for Santa's sleigh, but how would it work?
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Rudolph could use something many organisms use on Earth in order to create natural light, a neat little scientific trick called bioluminescence. Some animals can make their own light by mixing certain chemical compounds together to produce a glow. The reasons vary; fireflies, for instance, flash light at each other in order to attract mates, while some fish that live very deep in the ocean use light to locate prey.

So first let's talk about the parts of Rudolph's nose. It's just like any other reindeer nose: He breathes oxygen through it, and it's made up of two layers — the dermis, the thick, inner layer of skin that contains blood vessels and hair follicles; and the epidermis, the thin, outer layer that you can see and touch. The rest of his nose, however, would set Rudolph apart from all the other reindeer. (His playmates technically shouldn't shun him from any reindeer games, though.)

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What we're referring to as unique to Rudolph is a thin, enclosed layer of a light-producing organ between the dermis and the epidermis. Inside this layer is luciferin, a light-producing substance, and luciferase, an enzyme that catalyzes the light-producing reaction. And this where the "red-nosed reindeer" part comes in. Most bioluminescent life forms produce green light. The outermost part of Rudolph's nose, however, is a red phosphorescent layer. Once Rudolph's light-producing nose started creating light, the phosphorescent part absorbed the green light and emitted a red light instead.

How would his nose get so bright, though? Bioluminescence often requires another substance, like oxygen, to make light. Because Rudolph produces light in his nose, it only makes sense his nose would shine intensely and bright because he breathes oxygen into his nose where the light is created.

But why is Rudolph the only reindeer with a nose that glows? In the next section, we'll learn about how and why Rudolph has a muzzle like no other.

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Rudolph and Evolution

Rudolph the red-nose reindeer
Rudolph's glowing red nose comes in handy for leading Santa Claus' sleigh around the world on Christmas night. Luis Carlos Torres/Shutterstock

So we know that Rudolph stands out a bit from other reindeer, but how could he be the only reindeer with a big red nose? Is Santa some kind of a mad scientist that's tweaking reindeer DNA for his own benefit, or was Rudolph's nose an accident of biology?

It's possible that Rudolph's glowing honker could be a reindeer atavism. But what's an atavism?

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An atavism is a trait of distant ancestors that randomly pops up in modern-day organisms — a whale with legs or a human with a tail are two examples. These traits may have served a purpose for the animal way back when, but for whatever reason the trait was "silenced" over time, making rare triumphant returns in modern times.

Could distant reindeer ancestors of Rudolph produced light to survive in the wild? You'll find most reindeer in Scandinavia, and it does get pretty dark there during the winter, so could Rudolph's ancestors required a better way to get around at night?

Possibly, but that doesn't explain why only Rudolph has a bioluminescent nose. When we look closer at Rudolph's childhood, however, it could be that his bright nose was a rapid evolutionary adaptation. It's possible that the real reason Rudolph couldn't play in all those reindeer games was due to his poor eyesight; maybe he developed the red nose in order to compensate, and it just happened to save Christmas when Santa really needed it.

Although his playmates treated him like a misfit in the beginning, Rudolph actually proved himself to be the stronger specimen. Determined to excel, he could have adapted out of necessity. The question now is whether or not future generations of reindeer could also take on Rudolph's unique traits.

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Originally Published: Nov 20, 2007

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More Great Links

  • Lambert, Katie. "How Atavisms Work." HowStuffWorks. https://science.howstuffworks.com/atavism.htm
  • Wilson, Tracy V. "How Bioluminescence Works." HowStuffWorks. https://science.howstuffworks.com/bioluminescence.htm
  • "Evolutionary 'fast-track,' in which the hunted outwit their hunters, could explain why human diseases progress so rapidly, Cornell biologists report." July 16, 2003. Cornell News. http://www.news.cornell.edu/releases/July03/rapid.evolution.hrs.html

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