No, this is not a still from the movie Avatar.
It is one of the most surreal phenomenon taking place on the very beaches of Vadhoo island of the Maldives aptly nicknamed, ‘Sea of Stars’ after its appearance of the glistening glowing blue waves that touch the shores.
And that’s not it. This phenomenon can be seen anywhere around the world where algal blooms thrive on ocean surfaces albeit during certain time periods. Ironically, as beautiful as these flashes of color may appear visible at night time, bioluminescence is a defense strategy adopted by tiny marine planktons called Dinoflagellates. Belonging to the kingdom Protista, these planktons tend to express visible color triggered by mechanical stress when they sense a threat – be it flow agitation of waves or being attacked by predators . This is why when the waves hit the shores, flashes of blue appear.
Dinoflagellate planktons are unicellular which means that the organism is made up of a single cell. They have some characteristics of animals, as in, they can move around (locomotary) and they can also make their own food (photosynthetic) like plants do. The chemistry of bioluminescence is due to the influx of protons into small vesicles present at the edges of the vacuole of the cell. These vesicles known as Scintillons are lined with proton channels and encapsulate a protein called Luciferin. A sudden change in the tidal movement will open these channels leading to an increase in the proton concentration within the Scintillons thereby releasing the luciferin which, in the presence of luciferase enzyme, oxygen and water, gets transformed into a light producing molecule. I will be covering more on the mechanism of luciferin and its applications in life sciences in my upcoming post.
Of ecological significance, dinoflagellate’s bioluminescent strategy my help some of the organisms that are being attacked to raise an alarm attracting secondary predators to eat primary predators putting them literally in the spotlight thereby altering their feeding response. However, in the process, some of these phytoplanktons are bound to lose their lives to predators but it may lead save the rest of the population.
Check out this video posted by Nat Geo capturing bioluminescence on camera.
An interesting read on marine bioluminescence:
Widder EA. Bioluminescence in the ocean: origins of biological, chemical, and ecological diversity. Science. 2010 May 7;328(5979):704-8.