Deep under the North Atlantic, scientists have discovered a rare system of smoking volcanic vents and three-story "chimneys," according to scientists aboard the research vessel Celtic Explorer.

A hotbed of "evolution in overdrive," the site teems with strange animals that have been living there "perhaps for a millennium," said marine biologist Jon Copley. "And we're the first to see this place."

The vent field lies along the Mid-Atlantic Ridge, an undersea mountain range extending the length of the Atlantic that's created by the slow separation of tectonic plates.

The first hydrothermal vent zone to be explored on the ridge north of the Azores (map), the smoker site lies some 9,850 feet (3,000 meters) underwater, said expedition leader Andy Wheeler. (Read the deep-sea vent expedition blog.)

"It exists at the bottom of this steep, 650-foot [200-meter] fault escarpment." The teams remotely operated vehicle (ROV) "descended down the side of this cliff—and the side of the cliff was coated in bacterial slime—until we could see plumes of smoke coming up from below, and we found the chimneys reaching up," added Wheeler, a geologist at Ireland's University College, Cork.

Deep-sea chimneys are created when volcanically heated water carries metal sulfides up from below the seafloor. As the minerals pile up, the knobby towers take form.

Some of the study sites were so deep that the team's roughly SUV-size ROV—limited by its 3,000-meter (9,850-foot) tether to the ship—could investigate only chimney tops and cliff sides.

"We really were pushing the machines we had to the edge," said marine biologist Patrick Collins of the National University of Ireland. "And that's a credit to the ROV pilots—they pulled it off."

By the end of the ordeal, the researchers had christened the tower-spiked site Moytirra—"plain of the pillar"—after a battlefield of Irish myth.

Such pillars may someday be prized not only for their scientific richness but also for their ability to enrich corporate coffers, expedition leader Wheeler said.

"These chimneys, in many cases, have higher metal concentrations than some land-based ore reserves, so there is some economic interest," he said. "Some shallow-water examples are being looked at for potential deep-sea metal mining."

Such reserves might even be renewable, in a sense, because the chimneys grow over time, Wheeler added.

(Watch a video of hydrothermal vents.)

Creatures of the Alien Deep

Much of the attention focused on hydrothermal vents centers on their wide varieties of unusual ocean life—and Moytirra is no exception. (See pictures of hydrothermal vents.)

The newfound vents are home to a menagerie of creatures adapted to darkness and crushing water pressures, species that thrive despite waters volcanically heated to near boiling. (See "Earth's Hottest 'Bods' May Belong to Worms.")

High-definition pictures and video as well as collected specimens reveal orange shrimp, twisting scale-worms, eel-like fish, and swirling mats of bacteria.

"One shrimp we found, that's been seen at other sites, has lost its eyes but developed a new type of 'eye' on the top of its thorax that senses near-infrared light," he said. The vent shrimp's mysterious photoreceptor doesn't have a lens and so can't form an image, but the feature may be tuned to detect the very faint light produced by the hydrothermal vents.

"It's an example of what happens to organisms when they become isolated and evolution goes into overdrive," Wheeler said.

Soon animals collected by the crew will undergo lab analysis, and the researchers' hopes are high. The National University of Ireland's Collins said, "We're going to get lots of answers out of it and add to the history we have for vent ecology. But it's also going to pose lots of new questions."

Deep-Sea Mystery

Among the questions the team hopes to answer: How did these creatures get here?

The isolated chimney field represents a key midpoint between vents south of the Azores and north of Iceland—leading researchers to wonder whether the Moytirra species originated in one of those two locations.

"We're trying to see how this new vent site is related to its neighbors," said expedition leader Wheeler.

"There is a lot of research to be done, but one thing that's obvious is that it has some associations with species of the Azores and that poses the next question: How did they get over the shallow area of the Azores plateau and back down here into the deep?"

That mystery and others could be solved sooner rather than later, given the relative convenience of Moytirra, said Copley, whose work was funded in part by the National Geographic Society's Expeditions Council. (The Society owns National Geographic News.)

"This is the closest known deep-sea vent field to mainland Western Europe," he said. "So I'm hoping this is something we'll be able to visit repeatedly to see how these systems change over time. That's something we don't understand well here in the Atlantic."