The Neon Glow of Bioluminescent Sea Creatures

A bioluminescent firefly squid. (Photo: Visuals Unlimited/Getty Images)

Each year on the western coast of Japan, nature creates a particularly unique spectacle. Just under the surface of Toyama Bay, between March and June, firefly squid gather themselves up from the depths to spawn. Their method of attracting a mate is exceptional: from their photophores—light producing organs—they emit electric blue light. For the captivated onlookers, it’s startlingly neon display of bioluminescence. 

Around 80 percent of ocean-dwelling organisms emit light, according to the National Oceanic and Atmosphere Administration (NOAA). Various types of deep-sea fish, krill, jellyfish and comb jellies, marine worms and plankton are all bioluminescent. Many of these creatures reside in the so-called “twilight zone” of the ocean: the depths between 600 and 3,300 feet, where sunlight barely reaches.

Bioluminescence is created by a chemical reaction, for a variety of purposes—anything from camouflage to communication to attracting prey. Regardless of what it is used for, the other-worldly neon glow of bioluminescent life is extraordinary to behold.

A sea walnut—a type of comb jelly. (Photo: Steven G. Johnson/CC BY-SA 3.0)

An Argyropelecus hemigymnus, a type of deep-sea hatchetfish, feeding.  (Photo: Prof. Francesco Costa/CC BY-SA 3.0)

Noctiluca scintillans - also know as Sea Sparkle - light up the surface of the water in Zeebrugge, Belgium (Photo: © Hans Hillewaert/CC BY-SA 4.0)

A Tomopteris, a type of marine worm that exhibits yellow bioluminescence. (Photo: uwe kils/CC BY-SA 3.0)

A red ctenophore, or comb jelly. They live at around 3,280 feet in depth. (Photo: NOAA Photo Library/CC BY 2.0)

Antarctic krill. The bioluminescent organs are visible at the base of the eyestalk and thorax.(Photo: NOAA Photo Library/CC BY 2.0)

An aequorea victoria jellyfish. (Photo: Kondratuk Aleksei/shutterstock.com)

The zooplankton Beroidae. (Photo: NOAA/Public Domain)