Decoding the Science Behind the Amazing Glowing Fireworm

The bioluminescent display of a female Bermuda fireworm, Odontosyllis enopla, is something to behold. (Photo: Dr. James B. Wood)

The key to catching one of nature's most beautiful and peculiar mating displays is all about the timing. In fact, without a stopwatch synced perfectly with the last ray of light from the setting sun, it's possible you'll miss it altogether.

In summer and autumn, three nights after a full moon, female Bermuda fireworms wait exactly 55 minutes after the setting sun to begin their ascent to the surface. Once there, they glow a luminous green while moving in tight circles. Males, waiting on the bottom, see these displays and, like glowing green rockets, quickly burst to the surface to join the females.

"There's a little explosion of light as both dump their gametes in the water," Mark Siddall, a curator in the American Museum of Natural History's Division of Invertebrate Zoology, said in a statement. "It is by far the most beautiful biological display I have ever witnessed."

On Oct. 11, 1492, these seemingly magical displays also likely caught the attention of Christopher Columbus and his crew. Before making landfall in America, Columbus recorded from the Santa María a bizarre faint light like "the flame of a small candle alternately raised and lowered." The phenomenon remained unexplained until the 1930s when naturalist Lionel Ruttledge Crawshay proposed in a paper that it could be related to the luminous mating swarms of the fireworm.

You can see a short video of that mating display below.

In an effort to decode the mystery behind this beautiful display, Siddall and a team of researchers at the American Museum of Natural History analyzed the RNA molecules of a dozen female fireworms. Their work, published in the journal PLOS ONE, shows that the worms glow because of a special luciferase enzyme that's unique to the species. While all bioluminescent organisms, from fireflies to luminous mushrooms, utilize luciferase, the version inside fireworms could serve as the basis for new biomedical applications.

"It's particularly exciting to find a new luciferase because if you can get things to light up under particular circumstances, that can be really useful for tagging molecules for biomedical research," said Michael Tessler, co-author of the study and a postdoctoral fellow in the Museum's Sackler Institute for Comparative Genomics.