Bioflorescence Abounds

Bioflorescence Abounds

By Jessica Melanson, Journalism, 2014

Fluorescence in fish often goes hand in hand with ever-controversial genetic modification — like fluorescent zebra fish used in cancer research, or the popular pet, GloFish, the only genetically modified pet allowed to be sold in the United States. Yet in a new and unexpected discovery, scientists have identified over 180 fish in which biofluorescence occurs naturally.

Glowing in shades of green, red, blue, and orange, they vary in levels and amounts of fluorescence, from just circles around the eyes to full-body fluorescence coverage. John Sparks, lead author of the study, told the LA Times, “There is a whole light show going on down there. There have been studies on corals that are biofluorescent, but for fish, virtually nothing was known.”

Sparks and colleagues found biofluorescence to be widespread across phylogenetic groups, meaning that many kinds of fish with a distant common ancestor all experience varying levels of fluorescence. They found fluorescence to be especially common in cartilaginous fish, like sharks and rays, and bony fishes, like red lionfishes and seahorses. They theorized that the wide variability in coloration may have previously unknown importance in mating behaviors and other methods of communication. Biofluorescence was found to be most common in reef-dwelling fish.

Animals that are biofluorescent produce a special protein capable of absorbing light that then gets emitted from the animal’s body as a different color light. Fluorescence only takes place when there is ambient light, however; biofluorescent fish don’t glow in the dark.

While exploring reefs near the Bahamas and Solomon Islands, Sparks and his team found that certain fish have yellow filters built into their eyes that allow them to see only fluorescent light from fellow fish, cutting out any ambient blue light.

There are many ramifications for evolutionary research in the 180 species identified as biofluorescent, and Sparks said he plans to do more research into the phenomenon in the future.

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