Seas sparkle and glow at night in an array of different colors. It looks like the introduction to a beach-themed romance movie, but what causes Mother Nature to put on such a stunning light show? The answer is bioluminescence. Water glows because of the presence of bioluminescent algae and creatures. This bioluminescence is a natural chemical process that causes creatures and plants alike to glow and emit light to confuse predators, and attract prey or potential mates.
While these creatures are relatively rare on land (except fireflies), they are very common in the oceans and are usually found at depths between 200-1000 meters. Bioluminescence is very commonly found among fish, squid, jellyfish, and even some sharks.
Deep sea environments are dark, yet light is important even in these areas. The ability to glow in the dark also serves as an effective survival strategy, helping these creatures hunt for food, mate, and safeguard themselves from predators.
The chemical reaction that results in bioluminescence, requires two main chemicals- Luciferin, and photoprotein. In a reaction, the arrangement of the luciferin molecules determine the bioluminescent color (yellow in fireflies, green in lanternfish etc).
Many creatures like plankton synthesize luciferin on their own, and many others absorb it from other organisms either by consuming them, or through a symbiotic relationship. Most marine bioluminescence is expressed in the blue/green lines of the visible light spectrum.
This phenomenon highlights the incredible versatility and adaptability of marine organisms and gives us a snapshot of what life is like in the deepest, darkest depths of the oceans. As we discover newer methods to understand bioluminescence, we get closer to discovering many such secrets under the sea.