Deep Water Rave: Biofluorescence in Fish

From the magical glow of fireflies at night, to the mesmerizing orb of the deep sea angler fish designed to lure prey, most people are familiar with nature’s glowing creatures. This is due to a process called bioluminescence. These animals create their own light by producing a chemical called luciferin, which chemically reacts with oxygen to release energy in the form of light.

A similar process called biofluorescence occurs when one wavelength of light is absorbed, and then converted into a lower energy and higher wavelength, resulting in a different color of light. Recently, it was found that  more than 180 species of biofluorescent fish swimming in the waters. Fishes from the Cayman Islands, the Bahamas, and the Solomon Islands were imaged and scanned for fluorescence using special LED light sources and filters, and the results presented a wide variety of patterns and colors.

Diversity of fluorescent patterns and colors in marine fishes. A, swell shark (Cephaloscyllium ventriosum); B, ray (Urobatis jamaicensis); C, sole (Soleichthys heterorhinos); D, flathead (Cociella hutchinsi); E, lizardfish (Synodus dermatogenys); F, frogfish (Antennarius maculatus); G, false stonefish (Scorpaenopsis diabolus); H, false moray eel (Kaupichthys brachychirus); I, false moray eel (Kaupichthys nuchalis); J, pipefish (Corythoichthys haematopterus); K, sand stargazer (Gillellus uranidea); L, goby (Eviota sp.); M, goby (Eviota atriventris); N, surgeonfish (Acanthurus coeruleus, larval); O, threadfin bream (Scolopsis bilineata). doi:10.1371/journal.pone.0083259.g001

In deep sea waters, red, yellow, orange, and green light gets filtered out, leaving only the wavelength of light that we perceive as blue light. Using biofluorescence, these fish species absorb the blue light, and convert it back to a lower energy of light, thus re-emmiting the red, yellow, orange, and green colors seen above.

Scientists are currently studying this broad diversity of biofluorescence to determine it’s evolutionary advantages and adaptations to marine life. One hypothesis is that the variations of color and patterns may be used to attract a mate, similar to the way a male peacock will flash his patterned feathers at a female. Another possibility is that different colors and patterns are suited for camouflage within biofluorescent coral reefs. There have also been studies about using biofluorescence as a type of “hidden communication” between the species; they flash their light to one another to signal that a predator is nearby. This silent communication is possible because the light emitted is at a wavelength that the predator itself can’t see.

While most of us will never get to see these beautiful creatures for ourselves, we can close our eyes and envision ourselves swimming in the dark surrounded by glowing flashes of reds, yellows, and greens – nature’s version of a dance rave in your imagination!

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