Bomb-tastic new worms

Scientists find previously unknown deep-sea species that launch bioluminescent packets

Newly discovered deep-sea worms launch luminous green bombs that may distract a predator, a study in the Aug. 21 Science reports.

Remotely operated vehicles found seven new species of worms at depths around 1,900 meters and deeper off the coasts of California, Oregon and the Philippines. Cameras caught the worms, some of which were several inches long, swimming forward and backward above the ocean floor, propelled by wriggling fans of bristles.

BOMBER WORMS Some of these newly discovered species of swimming worms release glowing bombs, possibly to confound predators. Swirly lines show a hypothetical evolutionary relationship among the new species, with a potential ancestor worm at the bottom. © 2009 Karen J. Osborn

GREEN TRACE Researchers named one newly identified species of worm Swima bombiviridis, a fitting name for a swimming worm that can drop green bombs. The arrow points to several bombs behind the worm’s head. © 2007 C. Dunn

Cameras also caught a glimpse of small bulbous packets near some of the species’ heads. And researchers captured the worms to study their behavior. When prodded in a dark laboratory, the worms released one or two of these spheres, which burst into bright green light for seconds before fading. This trick earned the packet-carrying worms the nickname “green bombers.”

Once one bomb is released, the worm slowly grows another in the same place, says study coauthor Karen Osborn of Scripps Institution of Oceanography in La Jolla, Calif. “It takes them awhile to regenerate, so they’re stingy with them.” The seven discovered species make up a new genus, named Swima, and five of the seven make bombs, the study found.

Other animals, including some brittle stars and squids, use bioluminescence to distract predators. The worms’ glowing bombs may serve to distract a hungry fish, Osborn says. Because the bright lights from the remotely operated vehicles prevented the researchers from seeing the bombs’ glow in the deep ocean and no predators were seen attacking the worms, the scientists don’t yet know for sure why the worms deploy the bomb in the wild.

Cataloguing the species that live in the deep sea and understanding how they behave is important because diverse creatures keep an ecosystem stable, Osborn says. “Every time we go down, we find new species,” she says. “It’s important to learn about the biodiversity down there before we lose it.”

Laura Sanders is the neuroscience writer. She holds a Ph.D. in molecular biology from the University of Southern California.

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