system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How exactly do fireflies light up?
gpt
The firefly produces a chemical called Luciferin in its lower abdomen. It also produces an enzyme called luciferase which, in the presence of magnesium ions, oxygen and ATP (adenosine triphosphate), breaks down Luciferin and gives off light as a byproduct.