In 1998, University of Delaware marine biologist Craig Cary and his colleagues made international headlines when they determined that the Pompeii worm, which lives at hydrothermal vents, is the most heat-tolerant animal on Earth, able to survive a bath as hot as 176°F.

While some bacteria thrive at higher temperatures, the Pompeii worm ranks as the most heat-tolerant among complex life forms. The former record holder was the Sahara Desert ant, at 131°F.

Discovered in the early 1980s by French scientists, the Pompeii worm (Alvinella pompejana) is about 4 inches long with tentacle-like, scarlet gills on its head. A gray "fleece" of bacteria covers the worm's back.

The worm gets its name from the Roman city of Pompeii, which was destroyed during an eruption of Mount Vesuvius in 79 A.D. The Alvinella in the worm's scientific name stems from the submersible Alvin.

"The Pompeii worm makes paper-like tube colonies attached to hydrothermal vent chimneys," says Dr. Cary. "While the very hottest water shoots out the top of the chimneys, these structures are so porous that hot water also seeps out the chimney sides and through the worm's tube home."

The worm also displays a remarkably broad temperature gradient along its "hairy" body. By inserting a temperature probe called "the Mosquito," from the submersible Alvin into the worm's tube, Dr. Cary found that the worm's rear end sits in water as hot as 176°F, while its gilll-covered head, which often pokes out of the worm's tube home, rests in much cooler water, only about 72°F.

During the Extreme 2004 expedition, Dr. Cary and his team from the University of Delaware College of Marine Studies and Dr. Alison Murray and her research group from the Desert Research Institute in Reno, Nevada, will be working together to learn more about the Pompeii worm's incredible heat tolerance by studying the bacteria that live right on its back.

"The gray fleece, or "hair," that you see on the worm's back is actually bacteria," Dr. Cary notes. "Tiny glands in the worm's skin secrete a mucous that the bacteria appear to live and feed on."

"We're working to apply new genomics technologies to learn how these bacteria deal with the hydrothermal vent environment they inhabit in association with the worm," Dr. Murray adds.

Using tools borrowed from the Human Genome Project, such as DNA sequencers, the scientists will be working to access all the genetic information tied up in the bacteria -- their DNA code, or "road map of life," as Dr. Murray refers to it.

"Yet just as a road map has many more routes than are necesary for getting from one destination to another, a microorganism's genome can code for many, many pathways for carrying out its daily requirements," she explains. "The route that's actually taken on that road map represents the genes that are 'expressed,' or 'turned on,' at any given times. That's what we're looking for."

"Dr. Murray says this information will help address key questions about the sources of energy and food the bacteria use. The gene expression profile also can reveal other intriguing information, such as the genes involved in heat tolerance, metal detoxification, and cell-to-cell communication.

The Pompeii worm and its bacteria are of interest to industry, as well as the scientific community, because they may yield a variety of products and applications, from new pharmaceuticals to enzymes capable in operating in hot, corrosive, high-pressure environments. Such enzymes can help dislodge oil inside wells, convert cornstarch to sugar, process food and drugs, and support a number of other industrial processes by speeding up chemical reactions.