by chelsea schuyler

Bioluminescence is the mixing of chemicals together to emit light. A natural glow stick.

Yeah, whatever, how?  Well, a lot of different ways cuz this particular trait has evolved in different creatures many times. ANNOYING. But basically there’s two ways. Light organs, or bacteria.

LIGHT ORGANS: (which are always casually mentioned in articles as if they’re not the most amazing thing ever. Just pick one up on the way home. Um, light organ! People, amazing! Next you know they’ll be talkin’ about ‘fire organs’ used by dragons. Yeah, you know, fire organs and then fire came out. Taco?).

ahem, LIGHT ORGANS: You might think of a light organ as a layer of skin, which is also an organ (which is just confusing, i’d like to speak to the organizer of these terms). This layer of skin is made of eye-like cells. Let’s go with that, eyes. The pupil constantly radiates light, but the eye itself is neurologically controlled and can squint, close, or open wide, changing the amount of light emitted in different places at different times.

so how do the ‘eyes’ emit light?  Beware, chemistry alert. The creatures have luciferins, and use the enzyme luciferase to mix with it and the reaction produces light photons. It really is just like a glow stick, except with enzymes instead of hydrogen peroxide.

It sounds like i’m being technical (bad chelsea!) but i’m actually using the generic terms. “Luciferin” (latin for “bringer of light’) just means a molecule that emits light, of which there are many different kinds with even more complicated names.  It’d be like asking what the kids have at the cafeteria and hearing “food” when really each kid has a bagel, or a sandwich etc.  Basically it’s Science’s smart-talk way of saying “Light is there because ‘light’ is there.”  We’re also accepting “the origin of this animal’s light is ‘light.’ Yep.” But they do it to save you from going into all the different molecules that just look boring and remind you why you hated Chemistry in college.

The REAL question is, where do all the different luciferins come from? Well, the jury’s still out on that. Some sources are kind of known.  Dinoflagellates, the little plankton responsible for lighting up oceans, get their food from photosynthesis, and their luciferin resembles chlorophyll. The brighter the sun the day before, the brighter they are at night.

They think squid get it from their diet, but where their diet gets it from is an X file. Or maybe it’s manufactured from their food after eating it, it’s not quite clear. Mystery! Love it!

OR they don’t get it at all.

BACTERIA: Some creatures realize that making your own luciferin is for suckers, so they employ bacteria. Food and shelter in exchange for light. I always would throw popcorn at the screen when no one would say how the creature tells the bacteria when to turn on and off!?! The answers are fascinating. The bacteria’s light does not, in fact, ever turn off. The creatures who have this symbiotic relationship with them 1) evolved flaps of skin like eyelids to cover them, 2) suck in the sacks of bacteria into their stomachs, 3) have fluorescent proteins that change the color. (Remember, fluorescence is absorbing light and emitting a different light, bioluminescence is mixing chemicals together to produce light. Compact Fluorescent Bulb vs glow stick).

coolest ever. and we get none of it. not mammals, not reptiles, not birds, not amphibians. but I guess it’s the trade off for having to look like this:

but wait, there is one, one mammal who defied the odds. Rudolph.  As to where rudolph gets his luciferin, i’m thinking he’s got an elf who “knows how to get things.”

So there you have it.    P.S. for a fascinating historical summary of the origins of the biblical name “Lucifer” equating the fallen angel and therefore the devil, and how this was possibly completely lost in the translation of hebrew to …everything else, click here.  Merry Holidays!