Alien sea worms that ride the current discovered

Last Updated: Wednesday, November 16, 2011 - 15:56

Washington: 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.

PTI



First Published: Wednesday, November 16, 2011 - 15:56

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