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Why Do Fireflies Glow? (Science Tumblr Ask)

(written around two years ago.)

Does this count? How and why do firefly’s glow? Like is there a reason they blink instead of constantly glowing? Is there an advantage from predators or something?

I’m not as well versed on this as cellular biology, but it definitely does count! (Fireflies are peak whimsy and give me sooo much joy so thank you for asking me this!)

If my memory (from wild krats but I will research some and include my sources) serves me correctly, male fireflies glow in patterns that they hope females will find attractive, and if the female firefly likes the male’s flashing patterns, they’ll flash back (two blinks and a pause).

See now here’s another species with more sensible mating rituals then human beings. (I say as a neurodivergent lithromantic who looks upon the society with distain)

Now the how part of their glow is not something I know off the top of my head, (I remember @neurospicysalsa posting about firefly glow in relation to vaccines, yet I cannot look on tumblr as I am writing this, alas) and thus…

LE RESEARCH

Oh so fireflies are beetles. WHileee I think bugs are adorable, I’ve never had a hyperfixation over them… so someone else like @bonesbeetle could probably tell me why that’s significant. 😅

According to the article, while fireflies originally used their bioluminescence to ward off predators, they now use it for mating purposes, and each species of firefly has a specific height for the male to fly, as well as thier own flashing patterns. The female also has their own responsive flash unique to the species.

Other fun facts before I try finding out the biochemical reason for the fireflies glow (I want the nitty gritty)

  • some fireflies are most active during the day, and use pheromones instead of light for mating purposes.

  • fireflies spend most of their life as larvae in the leaf litter, and sometimes as adults they don’t even feed. Sooo I imagine that they don’t live much of their life as adults and honestly… that would make for such an interesting fantasy race. Like imagine the society catering to these children and feeding them and the ones with the most power being the children… then there are these adults, in the final phase of their life, who go out with this fantastical bioluminescence to mate and such… like there could be plenty of interesting cultural things surrounding this and how they value childhood annnndd….

  • anyways

  • Many females are wingless

OKay now for this article’s answer on how fireflies glow

“Fireflies produce light in special organs in their abdomens by combining a chemical called luciferin, enzymes called luciferases, oxygen and the fuel for cellular work, ATP.”

… so my guess is that luciferases catabolize luciferin which requires ATP to power it and such and such and let me see if I can find something more in depth

OKay so luciferin refers to a few organic molecules. ‘The name comes from the Latin word lucifer, meaning “light-bearing.”’ which I think sounds cool af.

(OH WAIT THIS IS WHAT THE LINK CLICK PEOPLE WERE TALKING ABOUT WHEN THEY SAID THAT LU GUANG’s ENGLISH NAME COULD”VE BEEN LUCIFER HOLY HERBS WE WERE ROBBED) Each biolumiscent organism has luciferin and luciferase that’s unique to it. So the ones for fireflies are called ‘firefly luciferin and luciferase’

How the process works is that:

first luciferin, the substance to be changed to form light… like a glow stick that you break in half so it lights up, is oxidized. (The way I think about oxidization is that it makes the substance more positive. Oxidize has an ‘o’ and so does positive. Reduction has an ‘e’ and so does negative. Plus each pair of words has similar vibes ig.)

In this case, oxygen oxidizes luciferin, meaning that oxygen removes electrons from luciferin to make luciferin more positive (which sounds very ‘let there be light’ to me). Luciferinase completes this reaction, ‘breaks the glow stick’ so to speak.

(The way i imagine it, the protein removes the electrons, dumps it off to the oxygen to carry the electrons… which oxygen seems to do in a lot of situations, and with that, the luciferase has been ‘broken like a glow stick’)

… Britanica then goes into more detail on fireflies specifically.

So in order to power this reaction, ATP is needed. I should have an ask explaining ATP here, but in essence ATP has three phosphates at the end that aren’t held together by much, repel each other, and buzz with energy, if you break that last phosphate off, it releases energy that enzymes can use for reactions. (I’ve… regrettably, only taken AP bio and while I do want to learn biochemistry… other requirements must be met. Alas. So what I do remember is that the mechanism that ATP powers the reactions through is typically through ‘giving’ a phosphate to the substances/whatever complex is created, which opens the floodgates for that stored energy.)

So in that ‘giving a phosphate to power the reaction way’, ATP reacts with firefly luciferinase, ionic magnesuim, and firefly luciferin to form a complex.

This complex: ‘complex (luciferase-luciferyl-adenylate) and pyrophosphate’ bunch of fancy words… and I’m… assuming the extra phosphate from the ATP made the pyrophosphate? ‘pyro’ sounds like pyruvate but I’m not sure… alas… I require more knowledge.

The way I think of complexes are these ‘power ups’ from tv shows, the ones like voltron or smth where a bunch of robot things combine with each other to form something more powerful or useful. How this actually works is that all the ingredients go into the active site (notches in the protein that will fit with the substances like puzzle pieces, then they change shape to cause the substances to react. The way I have this story-fied is that active sites are these wants with notches and enzymes will fit these around substances to do magic wowowo) of the luciferase and the luciferase initiates the reaction like a minecraft crafting table.

(I’m telling you there should be a minecraft adjacent game to learn biochemistry. I would lovvveee that.)

Oxygen then oxidizes (removes electrons) from the complex. Now it’s at a higher energy - and usually the universe likes low energy, balanced entropy rather than any condensed energies anywhere - so to release the energy, light emits through photons.

That was the rambling answer. Thank you for asking this! The name Lucifer for Lu GUang will never leave my head and this was an really interesting thing to learn about… now to find someone to catch fireflies with so I can infodump. (Sadly my parents never listen to/shuts down all my infoumps)

In the meantime, firefly playlist because I’m very normal about firefly whimsy:

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