National Geographic News
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Shown in its first ever photo, one of the world's deepest undersea volcanic vents erupts earlier this year.

Photograph courtesy National Oceanography Centre and University of Southampton

Brian Handwerk

for National Geographic News

Published April 11, 2010

Three miles (five kilometers) below the surface of the Caribbean Sea (map), great volcanic chimneys gush subterranean water hot enough to melt lead.

Found via robotic submersibles on April 6, these two-story-tall "black smokers" are the world's deepest known hydrothermal vents, scientists announced from aboard a research ship Sunday.

"It was like wandering across the surface of another world," geochemist Bramley Murton, speaking in a press statement, said of steering a submersible around the record-breaking volcanic vents.

"The rainbow hues of the mineral spires and the fluorescent blues of the microbial mats covering them were like nothing I had ever seen before," said Murton, who, like the rest of the team, works with the U.K.'s National Oceanography Centre.

(Watch a video of hydrothermal vents.)

Adapted to extreme heat, darkness, and lack of oxygen, the creatures dwelling at the newfound volcanic vents may be akin to Earth's earliest life-forms or even, some speculate, indicative of what life might be like on other planets. But the team is keeping details about the creatures a mystery, at least until they've been thoroughly studied.

(Related: "Hydrothermal Vents Found in Arctic Ocean.")

Undersea Volcanic Vents May Be "Lost World"

The team discovered the deep black smokers during an ongoing expedition to the Cayman Trough aboard the research ship James Cook.

Stretching between Cuba and Jamaica, the trough is the world's deepest volcanic rift and is twice as far down as most known hydrothermal vents. Made of iron and copper ore, the newfound chimneys are half a mile (0.8 kilometer) deeper than any previously discovered black smokers.

(Related: "Deep-Sea "Smoker" Vent's Rumble Reveals Ocean Clues.")

The Cayman Trough, or Cayman Trench, is unconnected to the world's other mid-ocean ridges, which are formed by separating tectonic plates. As such, the trough could be home to unique species that have evolved there in island-like isolation—a lost world, in the researchers' words.

Or the trough's vents could be home to species like those found at mid-Atlantic smokers, such as shrimp and anemones, since currents linking the Caribbean and Atlantic might carry animals between the two regions.

The volcanic chimneys may even harbor creatures like those at eastern Pacific vents—tubeworms, clams—since millions of years ago the Caribbean and Pacific were connected by a seaway across what's now Central America.

The answer will have to wait. "We've only just started to study the marine life at this site and don't yet have a full picture of it," marine biologist Jon Copley told National Geographic News from aboard the James Cook. "It will then take more work to see how species here relate to those at other vents around the world.

"But once we have those results, these new vents should help to reveal what governs patterns of marine life at deep-sea vents," Copley said. "Those answers should also tell us about patterns of deep ocean life in general—and the deep ocean is our planet's largest habitat.

"Vents are great natural laboratories for understanding such patterns in that vast realm, just as terrestrial islands were for 19th-century naturalists."

(Also see "Hydrothermal 'Megaplume' Found in Indian Ocean.")

Smokers Harbor Life As We (Didn't) Know It

By conventional standards, life shouldn't exist at the vents. Everywhere else on Earth, organisms are dependent—in many cases indirectly—on sunlight for energy. But the vents are utterly dark.

And while the surrounding seas are only a few degrees above freezing, water surging from smokers can be as hot as 760°F (400°C) and is loaded with hydrogen sulfide, toxic to most species. Also, the water pressure is such that roughly the weight of a large car is borne by each individual square inch of surface area.

But life has adapted to the vents in unexpected ways. (See "Earth's Hottest 'Bods' May Belong to Worms.")

In the absence of sunlight, for example, organisms at the smokers produce energy not by photosynthesis but via chemosynthesis, using chemicals pouring out of the Earth's interior. And some vent microbes need no oxygen, which, like sunlight, was once considered a prerequisite for life.

(See pictures of hydrothermal vents.)

These species have inhabited the vents for many millions of years and may offer a window into Earth's primordial past.

"Deep-sea vents in some geological settings may give us insights into conditions in which life may have originated," Copley said.

"And in the 30 years that we've been exploring deep-sea vents so far, they've certainly opened our minds about the possible limits of life, whether on Earth or elsewhere in the solar system."

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