Flash Mob! Glowing in Fishes More Widespread Than Thought

By Mindy Weisberger, Senior Writer | June 8, 2016 03:10pm ET

In depths of the ocean where light  can't penetrate, there are fish that generate their own eerie glow — shining spotlights on their prey, flashing warning signs to deter predators, or trading signals within their own species.

And since the first of these creatures lit up the seas about 150 million years ago, the ability to produce  light — known as bioluminescence — evolved across fish species far more often than scientists suspected, according to a new study.

Researchers analyzed lineages of glowing fishes, tracing them back to their origins in the early Cretaceous period (145.5 million to 65.5 million years ago). They found that bioluminescence emerged 29 times in marine fish across 14 clades — groups that diverged from a single shared ancestor.

And there are likely many more instances of evolving bioluminescence radiating throughout the entire tree  of life, study co-author John Sparks told Live Science.

Sparks, a curator of ichthyology at the American Museum of Natural History in New York City, explained that before the study, bioluminescence was thought to have evolved just 40 times across all known species — so discovering 29 instances in fish alone is a very big deal .   

"Bioluminescence is so bizarre, for it just to evolve once is amazing," Sparks said. "But to show that it's evolved all these times independently just among marine fishes is almost shocking."

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