Written and illustrated by Sketchy Science. For the original post, click here.
One of the things that has always perplexed me about Christmas is the story of Rudolph the Red-Nosed Reindeer. As a child, I remember watching the clay-mation documentary about how Rudolph came to join Santa’s present-pushing squad but I never stopped wondering about why that lone reindeer would come with a built-in headlight.
As it turns out, I should have spent my time wondering about the whole flying deer thing because the glowing nose is relatively easy to explain (not that that makes it any less awesome). The fact is, as solitary as Rudolph may be in the realm of reindeer, he is in fairly good company across nature at large. All kinds of plants and animals in all kinds of environments ranging from the jack-o-lantern mushroom, to the angler fish, to the cookie cutter shark are able to produce light through a process called bioluminescence.
Luminescence is often referred to as “cold light” because, compared with the incandescence that makes light bulbs work, it requires and produces little to no heat. Not only does that make it safer for the animals doing the glowing, it makes the process far more efficient. Bioluminescence is achieved when a light producing chemical called a luciferin mixes with a catalyst that produces a chemical reaction (called a luciferase) in the presence of oxygen. Luciferins can be any number of naturally occurring chemicals. For example, the compound coelenterazine is responsible for much of the bioluminescence that occurs in the ocean.
The question of why some animals give off light is often more challenging to answer than the question of how they do it. For example, why would a single-celled plankton glow when it is disturbed by a fish? It seems like giving up your position in an ocean full of things that want to eat you is about the worst thing you can do. A number of explanations for bioluminescence exist, however.
In the case of glowing plankton, some scientists advocate the “burglar alarm theory.” The idea is that, by glowing when attacked, plankton alert any nearby predators to the presence of the smaller fish that feed on them. As the old saying goes: “The enemy of my enemy is my friend.” Other uses of bioluminescence include communication (nothing helps you find a mate like lighting up a crowded room), locating food (nature’s flashlight), attracting prey (who doesn’t want to find out what that glowing thing in the dark corner is?), self-defense (when in doubt, blind everyone.), or even camouflage (when viewed from below in the ocean, a glowing belly can help you blend in with the sun).
This is all well and good, but it doesn’t do much to explain our old friend Rudolph. How exactly, you might be wondering, does a reindeer join the ranks of glow worms and plankton? There are actually a few possible explanations. The first is that Rudolph isn’t actually the one doing the glowing. Many animals use the light given off by others (usually bacteria) by allowing them to live on or in their bodies. It could me that Rudolph just has a very convenient bacterial sinus infection that has become a symbiotic relationship. Another possibility is that Rudolph is just the first in a new evolutionary line of reindeer that have adapted to 6 months of darkness at the North Pole by developing nose-mounted spotlights to help them find food.
There is also a slightly more malevolent explanation. It could be that Santa, for all his good qualities, is also a mad-scientist with no scruples about playing God. Maybe, faced with another dark and stormy Christmas Eve, Santa and his elves felt the need to genetically engineer a reindeer that could guide them through the black abyss. Surprisingly, this idea wouldn’t even be a new one. Scientists at the Mayo Clinic in Rochester, USA have engineered cats that glow in the dark to help them study gene implantation and resistance to feline HIV. Other researchers are hopeful that one day we can replace inefficient streetlights with trees that light our way home. Whose to say Santa hasn’t simply repurposed the idea for more selfish ends?
So there you have it. This Christmas morning as you tear open the presents Santa left you, maybe stop and take moment to think about all the failed experiments that were probably tossed in the bio-waste bin at North Pole Laboratories. That jolly bastard makes me sick sometimes.
Sketchy Science is a weekly blog written by Steve Kux and illustrated by Geoff Lee. Sketchy Science articles relating to sustainability and conservation are published in partnership with The Starfish.