Diving into the phosphorescent depths of the ocean

As with so many other marine phenomena, one would almost allow oneself to believe that biofluorescence is of extraterrestrial origin. More 80% oceans are unexplored and, according to the NASA, we know more about the surface of the Moon than about our own seabed. Some phenomena like this are only just beginning to be understood.

According to David Gruber, marine biologist and National Geographic explorer, scientific interest in this phenomenon has grown over the past decade. He is at the origin of several advances on the subject, and more particularly of a study published in 2019 which showed how these animals produce these luminous effects thanks to molecules of which science did not know the existence. In 2014, he proved in one of his studies that biofluorescence is commonplace in over 200 species of fish. His research has also shown that some sharks (and even some reptiles like sea turtles) have the ability to glow in the dark; a revolutionary step forward National Geographic included in its ranking of twenty greatest discoveries of the 2010s.

According to him always, whether it is a question of diving with bottles or with a mask and a snorkel (practice called snorkeling), fluorescent excursions transform the most familiar reefs and spots to the point that we no longer recognize them. “People who think they have seen the ocean and know it well, suddenly, are simply blown away,” he says. According to him, this discreet glimpse of the marine scenes, although fantastic in its color, is not there only to entertain us. “These animals share a secret with us,” he says, and it’s our responsibility to use that knowledge to protect them.


The logistical aspect of a night dive is quite basic: “You put on a mask [teinté en] yellow and then you turn on your blue light and all of a sudden, especially near a coral reef, everything lights up,” says David Gruber. The reason behind this phenomenon, however, is a bit more complex than that.

Animals hear the world differently (we think of bats who communicate mainly through frequencies inaudible to humans), but they see it differently too.


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