Bioluminescence: Nature’s underwater light show

Have you ever experienced walking along the beach and discovering the sea sparkling in blue-green light? Eerie as it may seem, this light show is called bioluminescence and it is produced by nature itself and not by any supernatural forces.


The science behind this glowing phenomenon

Bioluminescence is the light created by a chemical reaction which takes place inside living organisms. Some bioluminescent organisms are found on land like fireflies and fungi but the majority of glowing living things reside in the ocean such as bacteria, fish, squid, jellies, and more.

Many of the amazing natural light show appearances take place in the ocean. In fact, this phenomenon was observed back in 1832 when Charles Darwin wrote about the luminous specks in the water during one of his boat travels which were actually bioluminescent marine organisms flickering light.

These organisms generally exhibit blue-green light which is only visible at night time. They have the ability to control the intensity of the color and the moment they light up using a combination of chemistry and brain processes; depending on the situation and their immediate needs.

Reasons behind the aquatic light show

Hunting and feeding

The use of light can come in very handy during hunting and feeding times. Take, for instance, the deep-sea anglerfish which produces light from its esca to lure prey into its mouth while the cookie-cutter shark uses its glowing underside to lure other animals, both big and small. This opportunistic shark suctions on to its victims like squid, sea lions, and even whales then twists around to take a chunk of flesh using its sharp teeth.


Squids use their natural glow to attract prey as they make their way to the surface during the darkness of the night. Their cousins, the giant squids also use bioluminescence to hunt by producing blinding light flashes to confuse their prey. Although these deep-sea residents usually stay at a depth of 600-900 meters during the day, they seek shallower depths at night to hunt for fish and smaller squids. Scientists who have observed these giants also claim that they discharge different intervals and length of light bursts as a way to communicate with each other.


source: National Geographic Video

The glow in the dark features can be an asset during mating such as the yellow bioluminescent ring on a female octopus which helps attract mates while the female anglerfish uses its bulb-like appendage hanging above its mouth to get the attention of a male.

Some crustaceans like the ostracods go to the extent of regurgitating bioluminescent mucus that appear like luminous beads in the water to get the attention of potential mates.


Dinoflagellates, a type of water algae, give off a spectacular blue glow to ward off potential predators. They also produce light when they come in contact with other organisms or disturbed by the movement of the waves. These glowing algae may have been the root of many sailor’s ghost stories in the past inspired by sightings that they couldn’t explain.


Other creatures like the jellyfish also use their natural lighting properties as a means of self-protection. The light that they emit is often triggered by touch to startle predators. One particular species, called the comb jellies, are known to produce some kind of glowing ink that helps distract predators to give it time to flee.

Squids use their natural light as a defense mechanism called counter-illumination which makes them shadowless in the moonlight. Thus making it difficult for nocturnal predators to detect them.

While some self-preservation tactics are mild, there are some that may seem a little extreme. For instance, the deep-sea squid Octopoteuthis deletron detaches its glow-in-the-dark arms to distract predators and escape to live another day.

Experience this phenomenon during a night dive

If you want to experience this natural amazing wonder, you can go on a night dive in Cabo to witness it first hand. You can coordinate with your buddy so that at some point during your dive, you can turn your scuba torch off for a chance to see bioluminescent organisms. Try waving your hands around in the water and you might just be rewarded by the plankton’s bluish glow.

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