Skip to content

Why does ocean water glow at night?

Show answer & explanation

Answer: Bioluminescent plankton disturbed

Moonlight reflecting off wavesWrong. Moonlight creates shimmer but not the blue-green glow. The glowing comes from living organisms (dinoflagellates) producing light chemically.

Bioluminescent plankton disturbedCorrect! Tiny plankton called dinoflagellates contain luciferin and luciferase. When disturbed by waves, swimming, or boats, they produce a blue-green glow (bioluminescence) as a defense mechanism—possibly to startle predators or attract larger predators to eat their attackers. Millions create glowing waves!

Minerals glowing from sunlightWrong. Minerals don't glow at night from stored sunlight. The glow is biological—produced by living plankton through chemical reactions.

🚀 Play today's quiz — new questions daily

More Marine Life questions