Sunday, 20 November 2011

Alien sea worms that ride the current discovered

Scientists have discovered what they say “alien” deep-sea worms which dump ballast sand and sediment from their guts and catch a ride on an ocean current when they want to go for a trip.
The mysterious organisms, called enteropneusts, were once thought to be mostly shallow-water animals, but the new study showed that almost a dozen species living on the seafloor as deep as 12,972 feet.

The study showed a diversity of colour and shape in these worms, also known as acron worms, LiveScience reported.

These worms had been thought to be shallow-water species until 1965, when a deep-sea species was caught on film and changed that perception. The ensuing decades turned up a few more images of deep-sea acorn worms, but only two specimens.

Using remotely operated deep-sea vehicles (ROVs) from the Monterey Bay Aquarium Research Institute (MBARI) and from UK’s National Oceanography Center, the researchers set out to find more of these mysterious worms.

In most cases, the scientists, led by Karen Osborn of the Smithsonian Institution, piggybacked on past research missions, grabbing video of worms and even some specimens wherever the ROVs happened to be.

From the year 2000 to present, they captured 498 separate observations of deep-sea acorn worms, revealing a whole new world on the seafloor.

The researchers, who detailed their findings in journal Proceedings of the Royal Society B, found that the worms live in both the Atlantic and the Pacific Oceans. In addition to the two known species of deep-sea acorn worm, the researchers also found at least nine new species.

Perhaps more surprising than the worms’ ubiquity was their method of travel. For the first time, the team observed acorn worms drifting with ocean currents at anywhere from a few centimetres to 66 feet above the seafloor.

The video cameras caught the worms twisting and raising their bodies, suggesting that they deliberately launch themselves into currents to get around.

When feeding on the ocean floor, the worms’ guts were filled with sand and sediment. But in one time-lapse video, the researchers observed an acorn worm totally emptying its gut before disappearing from the feeding site.

That video suggests that the worms use sand as ballast to keep them on the seafloor when they’re eating, and then lighten their load for ease of travel, the researchers said.

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