Why do the bottoms of fireflies and lamprigera light up?!
A proper explanation is a little above ELI5, but for the purpose of this subreddit it’s enough to know that it’s a chemical reaction between the oxygen of the air and a some chemicals in the butt of the fireflies.
Think of it as a kind of combustion, but with no fire and very little heat
Fireflies light up by letting oxygen into their butts which causes a reaction with cells known as photocytes that then glow.