Innovations in Biotechnology and Medical Sciences

What is Milky Sea Phenomenon?


From UPSC perspective, the following things are important :

Prelims level : Milky Sea Phenomenon

Mains level : NA

Some researchers would use satellites to study the elusive milky sea phenomenon.

What is the Milky Sea?

  • Milky seas, also called mareel, is a luminous phenomenon in the ocean in which large areas of seawater appear to glow translucently (in varying shades of blue).
  • Such occurrences glow brightly enough at night to be visible from satellites orbiting Earth.
  • They are a rare nocturnal phenomenon in which the ocean’s surface emits a steady bright glow.

Why do they glow?

  • Luminous bacteria cause the particles they colonize to glow.
  • The purpose of this glow could be to attract fish that eat them.
  • These bacteria thrive in the guts of fishes, so when their populations get too big for their main food supply, a fish’s stomach makes a great second option.

How do they occur?

  • It is typically caused by Noctiluca scintillans (popularly known as “sea sparkle”), a dinoflagellate that glows when disturbed and is found in oceans throughout much of the world.
  • Once their population gets large enough – about 100 million individual cells per millilitre of water – a sort of internal biological switch is flipped and they all start glowing steadily.

UPSC 2022 countdown has begun! Get your personal guidance plan now! (Click here)

Get an IAS/IPS ranker as your 1: 1 personal mentor for UPSC 2024

Attend Now

Notify of
Inline Feedbacks
View all comments


Join us across Social Media platforms.

💥FREE for 24 Hours Prelims Notes
This is default text for notification bar