Hot-Water Worms May Use Bacteria as Shield

January 17, 2005

Scientists who recently returned from a deep-ocean expedition said they are a step closer to understanding how life thrives around cracks spewing scalding water at the bottom of the ocean.

The scientists were exploring hydrothermal vents along the East Pacific Rise about 1,200 miles (2,000 kilometers) west of Costa Rica as part of the Extreme 2004: Exploring the Deep Frontier expedition.

A principal aim of the expedition was to collect samples for a "metagenome project" to better understand how an exotic worm takes advantage of microscopic organisms on its back to endure repeated blasts of scalding water.

"We hit every one of our primary objectives and were able to collect more than we had hoped," said Craig Cary, a marine biologist at the University of Delaware in Lewes. "This is a successful cruise," said Cary, who organized and led the expedition.

In addition to collecting samples, the researchers encountered a new vent site loaded with exotic Pompeii worms (Alvinella pompejana.

Perhaps the biggest surprise came on the last dive of the cruise. Cary and colleagues aboard the submersible Alvin encountered a blinding storm of "marine snow"—dead and alive organisms floating through the water.

"It looks like there was a recent eruption at that site that we hope will be the beginning of a whole new system," Cary said.

The expedition was so successful in terms of discoveries and scientific collaboration that Cary said it was the best of his 22 consecutive years of such cruises. "I think it really had to do with the chemistry of the whole group," he said. "They just clicked, and when that happens, the science can move to a whole new level."

Metagenome Project

Cary's key scientific mission on the cruise was to collect samples for his metagenome project. "We are trying a new genomic strategy to help us understand how complex microbial communities interact and respond to their environment," he said.

The researchers are particularly focused on the community of the Pompeii worm, which is the world's most heat-tolerant complex organism known to science.

The worms live in papery tubes buried into the sides of hydrothermal vents. The water temperature at the bases of the tubes has been measured at 176 degrees Fahrenheit (80 degrees Celsius). Scientists believe the bacteria on the worms' backs act like firefighters' blankets, shielding the worms from intermittent blasts of hot, metal-rich water.

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