Volume 10, Number 3, 2001

Deep-Sea Vents Harbor Earth's Hottest Animal

In 1998, UD marine scientist Craig Cary and his colleagues made national headlines when they discovered that hydrothermal vents harbor the most heat-tolerant animal on Earth.

The Pompeii worm (Alvinella pompejana) -- a fuzzy gray 5-inch critter sporting tentacle-like, scarlet gills on its head -- can survive a bath as hot as 176°F.

While some bacteria can live at even higher temperatures, Cary says the Pompeii worm ranks as the most heat- tolerant among higher-order life forms. It beat out the Sahara Desert ant, which formerly held the record at 131°F.

"For most of us, a hot shower is around 100°F, says Cary. "How the Pompeii worm survives the nearly boiling water emanating from the vents is a mystery."

The Pompeii worm also displays a remarkably broad temperature gradient along its hairy body.

"The Pompeii worm makes paper-like tube colonies attached to hydrothermal vent chimneys," says 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 Pompeii worm's tube home."

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

As chief scientist for the Extreme 2001 expedition, which sets sail on October 15, Cary says the research team's chief objective will be to learn more about the Pompeii worm's incredible heat tolerance by studying its unique biology and the bacterial colony that lives right on its back.

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

These bacteria are particularly intriguing to scientists and industry because the microbes may harbor enzymes capable of 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.

"Every time we visit the vents, we find something new," says Cary. "By studying 'extremophiles' like the Pompeii worm, we can better understand this amazing ecosystem and the human benefits it may yield." His research is funded by a grant from the National Science Foundation.