Researchers have dubbed the newly discovered critters "green bombers."
The seven new species of worms were found by a team led by Karen Osborn of the Scripps Institution of Oceanography at the University of California, San Diego. They report on the worms in Friday's edition of the journal Science.
"We found a whole new group of fairly large, extraordinary animals that we never knew anything about before," Osborn said in a statement. "These are not rare animals. Often when we see them they number in the hundreds. What's unique is that their habitat is really hard to sample."
Ranging in size from three-fourths of an inch to nearly four inches, the worms live at depths of 5,900 feet to more than 12,000 feet and were discovered by remotely operated submarines in both the northeast and western Pacific Ocean.
"They have a very strange way of using bioluminescence," Osborn explained in a briefing.
They have appendages, some round, others oval or long, which they release when they are disturbed, she said. Once release the appendage, it glows bright green.
"They drop one or two at a time and if you keep harassing them they will keep dropping them," she said, adding that the worms are able to regenerate the body parts.
It's the first time this has been seen in swimming worms, she said, although some brittle stars and some squids will let an arm drop off if attacked.
"We're not sure who their predators are," added Osborn, but she noted that fish prey on other types of swimming worms.
The closest relative to the newly found creatures are worms that burrow in the sea floor, Osborn said, "at some point they moved up into the water."
The first of the new species has been given the scientific name Swima bombiviridis.
The discovery emphasizes how little is known about life in the deep oceans, the researchers wrote.
The research was funded by the Scripps Institution, University of California President's Postdoctoral Fellowship, David and Lucile Packard Foundation, National Oceanic and Atmospheric Administration, Woods Hole Oceanographic Institute and the National Geographic Society.
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