To Distract Predators, a Sea Worm Says "Bombs Away!"

By Eliza Strickland | August 21, 2009 10:04 am

worm bombs 1In the depths of the Pacific Ocean, several never-before-seen species of worm have been found that have a remarkable defense mechanism. Take, for example, the newly named species Swima bombiviridis. Thousands of meters below the sea, a tiny worm wriggles through the darkness, its dozens of paddle-shaped bristles moving in beautiful coordination. Suddenly, a hungry predator appears. The worm releases a glowing green sac, and the fish homes in on this bright new trophy. By the time the fish realizes the sac is no meal, the worm is long gone [ScienceNow Daily News].

Of the seven new species described in a paper in Science, five drop luminescent “bombs” that researchers think distract their predators, allowing the worms enough time to wriggle away backward. Study coauthor Greg Rouse explained that a common ancestor of the species had gills that appeared to be “in exactly the same places as the bombs”, from which the bombs could have evolved. “The gills (of their relatives) can fall off very easily so there’s a similarity of being detachable, but for some reason the gills have transformed to become these glowing little detachable spheres” [BBC News].

worm bombs 2The worms’ bombing operations haven’t yet been observed in their natural environment, because the bright lights needed to take pictures or video obscure the glow of the bombs. But when the worms were captured and prodded in a dark laboratory, the worms released one or two of these spheres, which burst into bright green light for seconds before fading [Science News].

The worms were first sighted by a remote control research vehicle that was cruising along the seafloor off the coast of California, and the critters have now been found off the western coast of North America from Oregon to Mexico, as well as in the waters around the Philippines. They appear to be rather common at depths ranging from 6,000 to 12,500 feet, says lead researcher Karen Osborn, but haven’t been detected before because of the difficulty of researching the briny abyss. Says Osborn: “This group of really fantastic animals emphasises just how much we have to learn about deep sea organisms and deep sea biodiversity” [BBC News].

Related Content:
80beats: To Keep Predators Away, Snake Pretends Its Rear Is a Second Head
80beats: Built-In Mirrors Help Spookfish See in the Dark Ocean Depths
80beats: Bouncing, “Psychedelic” Fish Is Declared a New Species
DISCOVER: Splendor in the Dark explains how fish glow

Images: Karen J. Osborn, S.H.D. Haddock 


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