The Glowing Ocean

glowing dinoflagellates

Dinoflagellates makes these ocean waters glow. (Photo credit: ArtTomCat/Shutterstock)

Whether seen from the beach or from the seat of a kayak, the glowing ocean is a phenomenon that, once experienced, is not soon forgotten. What causes this strange glow in the oceans water? And what purpose if any does it serve?

The phenomenon of the glowing ocean has fascinated sea travelers for a long time. Folklore from northern Europe, southeast Asia, and the South Pacific include reference to it. Aristotle (3rd century BCE) wrote his observations about the phenomenon in his work De Anima. During the Renaissance, when European explorers set sail across the worlds oceans, observations of bioluminescent organisms became even more widespread. Even Charles Darwin made note of the phenomena in his written journals from his time on the HMS Beagle in the 1830s. As Darwin observed,

” the sea presented a wonderful and most beautiful spectacle. There was a fresh breeze, and every part of the surface, which during the day is seen as foam, now glowed with a pale light As far as the eye reached, the crest of every wave was bright, and the sky above the horizon, from the reflected glare of these vivid flames, was not so utterly obscure, as over the rest of the heavens.”

The creatures behind the mysterious bluish-green glow in the oceans surface waters are tiny organisms called dinoflagellates. These single-celled organisms range in size from 30 m to 1 mm and can be found in waters around the globe. While an individual dinoflagellates glow is typically too dim to be seen by the naked eye, when their populations swell to high concentrations, their presence is unmistakable. Along the coastlines of the United States, dinoflagellate populations typically grow to high concentrations during the summer to late fall months, when water temperatures are warmer and the seas are calmer.

A dinoflagellates glow is an example of bioluminescence and is the result of an enzymatic reaction. In the reaction, oxygen reacts with a substance called luciferin. First, luciferin combines with ATP to form luciferyl adenylate and a phosphate group. Next, luciferyl adenylate combines with oxygen on the surface of the enzyme called, appropriately enough, luciferase. Light is produced when the oxygenated luciferin, or oxyluciferin, is released from the surface of the enzyme. Scientists think that the reaction evolved as a way to bind up excess oxygen, thus preventing cell damage. The light given off by the reaction was just a byproduct of the reaction, not originally its main function.

Dinoflagellates do not glow all the time. Instead, they flash their bluish-green light when movement disturbs the water they live in. Scientists hypothesize that the sudden flashing of light serves to startle and illuminate attacking predators. Rather than becoming lunch themselves, the dinoflagellates make their predators the prey for even larger organisms. And, in the ensuing chaos, the dinoflagellates are able to safely escape.

Of course, dinoflagellates arent the only organisms that exhibit bioluminescence. In fact, bioluminescence has evolved independently hundreds of times. The bioluminescent organism you are likely most familiar with is the firefly, also known as a lightning bug. This insect uses a similar enzymatic reaction to make the end of its abdomen glow, a familiar sight throughout the United States during warm summer nights. However, the majority of bioluminescent creatures call the oceans home, and bioluminescence is a common feature among those organisms that live in the deepest depths of the ocean, where no light penetrates.

Whether on land or sea, however, bioluminescence is another in the long list of those curious traits of our planets organisms; traits that, while only a byproduct of some other adaptation, come to serve the organism in other practical and fascinating ways.

More to Explore
Creatures of Light
How Do Glowing Algae Chemically Create Their Light?
Things That Glow in the Water At Night
Glowing Blue Waves Explained
Ocean Bioluminescence
Suggested Explanation for Glowing Seas–Including Currently Glowing California Seas


  1. Atlas Mitchell says

    I find it amazing that these tiny little organisms can create such an amazing sight.

  2. Destiny Castillo says

    This is so cool. I would love to see this in real life! Who knew that such a little creature could be the cause of this beautiful phenomenon.

  3. Landon Johnson says

    This would be so awesome to see in real life. I wonder if there is anything we could ever use them for to get things to glow. hmmmm.

  4. Kenny Buck says

    Am I the only one who already knew this? Maybe because I grew up on the west coast, where we learned how the Spaniards thought it was an act of god that the cross they left in the ocean for a week started glowing? Anyone else feel underwhelmed by this “Strange” Biology?

  5. Keaton Dotson says

    This is so crazy! I had no idea a tiny organism could make this incredible phenomenon.

  6. alex killeen says

    I would love to see this in real life too!

  7. alex killeen says

    This is amazing! i want to float in the water in a glass bottom boat!

  8. Keleigh Hogan says

    It is very interesting that they use their light as defense from predators.

  9. Ashlyn Stewart says

    It’s interesting that microorganisms can have such a bright effect on the ocean. These organisms show that even the smallest things in the world make a difference.

  10. Josh Couch says

    This is really amazing what these things can do. I wish I would be able to see this in real life.

  11. Josh Couch says

    I thought the same thing! It seems kind of weird how they can do this.

  12. Will Graham says

    Oh… So that is what causes that glow when I go down to the beach. Never thought it was living organisms creating that colorful light.

  13. Will Graham says

    Oh… So that is what is causing that mysterious glow in the water down at the beach… that figures.

  14. Darlene Piguet says

    We actually saw this in Oldsmar, Florida on June 25, 2016. When we moved the water it glow with a green light. It was beautiful and fun to play with.

  15. We have these in Florida! They’re beautiful and you can see them on the BK Adventure tours. They have amazing tour guides, even their sales team are extremely helpful and friendly. Their Bioluminescence tour is also incredible. Check them out if you’re in Florida. I have attached their website for everyone to check out!

  16. cool! this is awesome!

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