Cover image by: FOX Weather / Article written by: Jasmine Liu
Very rarely, the ocean can be seen glowing a bright white, turning into what looks
like a field of snow. This is known as the “Milky Sea” phenomenon, occurring only two to
three times a year. This mysterious phenomenon is actually triggered by the same
process for which fireflies light up and jellyfish glow: bioluminescence.
Bioluminescence is defined as “the ability of an organism to make light”,
occurring mostly in marine organisms. In fact, 76% of all ocean animals, and
approximately 90% of deep sea animals are bioluminescent. Well known
bioluminescent organisms include jellyfish, fireflies, bacteria, and certain sharks and
fish.
Why does bioluminescence occur? There are a variety of different reasons for
this process, all relating to each animal’s specific survival needs. Bioluminescence can
be used to deter predators, using the produced light to startle and distract the predator.
At the same time, bioluminescence is used to lure prey, drawing other animals to the
bright light. Other theorized functions include camouflage, communication, and to find a
mate.
The process of bioluminescence boils down to the reaction between two
molecules: the compound luciferin, and the enzyme luciferase (In Latin, the world
“lucifer” means light bearer). When these two chemicals are exposed to oxygen, light is
produced. While the light can range from red to yellow to purple, the most common
color produced is green-blue (because of its wavelength).
When a milky sea occurs, billions, if not trillions, of bioluminescent bacteria
gather and light up, enough light to be captured by satellites. However, due to the
rareness of this event, many questions about this phenomenon are still unanswered,
leaving the milky seas to remain, for now, a mystery.
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