Within the body of a luminescent jellyfish is a special protein, aequorin, which produces a green glow when it comes into contact with a calcium ion. The source of a firefly's glow is luciferin within its light-emitting cells, which produces energy through peroxide catalysis.
發光水母是因為體內特殊的蛋白質 (Aequorin) 碰上鈣離子後，產生綠色螢光；螢火蟲發光原因，則是體內發光細胞中的螢光素（一種含磷的化學物質）經過氧的催化作用，產生能量。