A glowing eel accidentally discovered by David Gruber while photographing bioluminescent corals

(Photo: David Gruber/National Geographic Creative) A glowing eel  discovered by David Gruber while photographing bioluminescent corals

‘She’s always buzzing just like neon, neon……Neon, neon….Who knows how long, how long…She can go before she burns away…’

These well known words to John Mayer’s, “Neon”, literally flicker on and off in my head as I sit and write this article in lieu of the amazing discovery  I’m about to share. Or rather, there have been a series of amazing discoveries revealed to marine biologists over that past few years and months that have been inextricably linked to what I’m about to share. These discoveries have proved to be very illuminating indeed.

Back in September, the world’s first bioluminescent reptile was captured on camera for the very first time. A group of marine scientists filming coral and sharks off of the Solomon Islands encountered a Pacific sea turtle glowing neon red and green during their night-time excursion. Such an encounter has opened up a whole new world of marine animals that create vibrant color in a nocturnal, watery galaxy. David Gruber, a marine scientist for the City University of New York and a National Geographic Explorer, is a fore-running pioneer in this new frontier of studying bioluminescence in marine vertebrates.

Back in 2011, while diving just off Little Cayman Island in the Caribbean, David Gruber was photographing species of biofluorescent corals one night when he received a most unexpected visitor. A small eel about the length of his finger popped up in one of his photos. However, instead of being lost among the vibrant, glowing corals, the eel itself stole the show by glowing a bright, neon green itself! Imagine Gruber’s astonishment and wonder!

special, fluorescent proteins found in muscle tissue allows these eels to glow

(Photo: David Gruber/National Geographic Creative) special, fluorescent proteins found in muscle tissue allows these eels to glow

“This big lightbulb went off in my head,” says Gruber. “I hadn’t expected a fish to be glowing as brightly as the coral.” 

This particular species of eel (Kaupichys) was the first fluorescent fish to ever be recorded and has since sparked a whole series of studies and investigations into this strange and fascinating new world. Since then, over 180 different species of biofluorescent fish have been discovered with Gruber’s aide. The ability to manipulate light within one’s environment, especially a water one, has the potential for unlocking a wide array of doors into the secrets of marine vertebrate behavior.

But you may be wondering…’What is the difference between bio-LUMINESCENCE and bio-FLUORESCENCE?!’ An animal capable of bioluminescence produces light through a series of chemical-based reactions that occur on or within their bodies. In addition, special bacteria that produce light are found living on bioluminescent animals. On the flip side, biofluorescence occurs when an organism absorbs light and can then reflect it back out as a different color. For example, the biofluorescent turtle that was recorded back in September in the Solomon Islands reflected red and green light when a specific, blue-colored light was shone on the turtle’s shell.

Now, four years later, Gruber has reached the light at the end of the tunnel and solved the mystery behind the glowing eel that first crossed his path. At Lee Stocking Island in the Bahamas, Gruber and a team of scientists captured two of the glowing eels that actually turned out to be two different species; one is the plain false moray eel (Kaupichthys hyoporoides) and the other is a completely new species! An up close and personal analysis of the eel’s tissues revealed something truly remarkable.

On a molecular level, an unknown group of fluorescent proteins was found on the muscle tissue of the eels that Gruber’s team captured. Gruber theorizes that at some point in their evolutionary past, these proteins journeyed from the eel’s brains to their musculature where they began to glow. The proteins were selected for a specific function that would aide in the eel’s productivity and survival. Gruber suspects that that specific function is for reproduction. Both of the species of biofluorescent eels in Gruber’s study are very reclusive and their special ability to glow may aide the eels in finding a mate under the light of a full moon. Moonlight glows a blue color and this, in turn, causes the fluorescent proteins found on the eels to re-emit green light just like the glowing sea turtle found in the Solomon Islands. The full moon is a time where many species of eels congregate in one place to spawn and reproduce young.

biofluorescence may allow eels to find a mate

(Photo: Alex Tyrrell) biofluorescence may allow eels to find a mate

Michael Miller, a scientist working for the Nihon University’s Laboratory of Eel Sciences in Kanagawa, Japan, agrees  that the ability to glow may be a way for the eels to find each other at night. Even though he wasn’t a part of the study, Miller quoted via e-mail: “And if most other predators can’t see that kind of light, then it would be a great mechanism to enhance spawning success and avoid predation.”  It would be just like a giant game of Where’s Waldo….only in the dark and with a glow stick.

Life in the water is a whole other world that is so different from our own out in the air. Light, color and sound have a different set of rules and regulations when it comes to traversing through this medium. Studying biofluorescence and how fish use this to create color can give us insight into how they navigate this vast, blue plane of existence. What a way to get us, stubborn humans to think outside of our own boxes and get on the level with other creatures with whom we share this amazing planet with! For once, let’s flip a switch and  look at it from their point of view.

*You can check David Gruber’s study in more detail in the journal PLOS ONE (published November 11, 2015). 

By Julie ‘Jules’ Cremer


Works Cited:

  1. John Mayer; Clay Cook, Douglas Cook. “Neon”. Sony/ATV Tunes LLC, Me Hold Your Music, Specific Harm Music. 1999.
  2. Jardin, Xeni. “Small eel photographed by accident on coral reef is first green fluorescent fish ever recorded”. boingboing.net. Web. 12 November 2015. Accessed 17 November 2015.
  3. Own, James. “Move Over, Glowing Turtle-Meet the Glowing Eels.” National Geographic online. 12 November 2015. Web. Accessed 17th November 2015.