The University Ghent, Belgium / Gaetan Borgonie
The nematode H. mephisto lives nearly a mile underground in rock fractures near South African gold mines.
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updated 6/1/2011 2:47:51 PM ET 2011-06-01T18:47:51

How low can worms go? According to a new study, at least 0.8 miles below the Earth's surface.

That's the depth at which scientists discovered a new species of worm, dubbed Halicephalobus mephisto in honor of Faust's demon Mephistopheles. The worm, reported this week in the journal Nature, is the deepest living multicellular organism ever found.

"We tried to get the title of the paper to be 'Worms from Hell,'" said study author Tullis Onstott of Princeton University. "But Nature didn't go for that."

The Moby Dick worm
Onstott and his colleagues have been searching for subsurface life for 15 years, focusing on the ultra-deep mines of South Africa, which penetrate more than 1.8 miles into the Earth. They and other teams of scientists have found that life has very deep roots, with single-celled organisms found miles underground. Some of these organisms are quite extreme: One 2008 study found life thriving a mile under the seafloor, surviving in temperatures between 140 and 212 degrees Fahrenheit.

But finding the multicellular, 0.02-inch-long H. mephisto is a different story. The worm, or nematode, lives in fluid-filled rock fractures, where it grazes on bacteria, Onstott told LiveScience.

"It's kind of like finding Moby Dick in Lake Ontario," he said. "It's so volumetrically big. It's 10 billion times the size of the bacteria upon which it feeds."

To find the worm, Onstott and his team sampled water from mine boreholes as deep as 2.2 miles. They also sampled soil around the mine boreholes and filtered about 40,000 gallons of surface water to ensure that the nematodes weren't coming into the mine from above.

In the Beatrix gold mine, they found their quarry: the tiny, simple nematode, alive and capable of asexual reproduction. The researchers were able to get H. mephisto to reproduce, and the species is still "squirming around in the lab," Onstott said.

The researchers found no evidence of the nematode in surface waters or soils, indicating that it is native to deep rock fractures. Chemical analysis revealed that the water in which H. mephisto lives dates back at least 2,900 years, meaning it's been down there for a while, said Rick Colwell, a microbiologist who studies subsurface organisms at Oregon State University.

"They have been quite careful in measuring the environment that these organisms come from," Colwell, who was not involved in the study, told LiveScience.

In lab experiments, the research team found that H. mephisto prefers to snack on the bacteria found in deep rock fractures, turning up its wormy nose at above-ground buffet options such as E. coli.

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Worms in space?
The find could encourage researchers to expand the search for life under our own feet, said Colwell, who along with others is working on a project called the Census of Deep Life, dedicated to cataloging what lies beneath Earth's surface.

"As we initiate this census of deep life," Colwell said, "I can see expanding it in the direction of some more complex life forms, like these nematodes."

Farther from home, the discovery of very deep multicellular worms opens up possibilities in the search for extraterrestrial life, said Michael Meyer, the lead scientist for Mars exploration at NASA, who was not involved in the study. Researchers have assumed that any subsurface life on a planet like Mars would be unicellular, Meyer told LiveScience.

"This kinds of opens it up to, well, even multicellular life could be possible," Meyer said.

You can follow LiveScience senior writer Stephanie Pappas on Twitter@sipappas. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.

© 2012 LiveScience.com. All rights reserved.

Explainer: Top 10 oddballs of the animal world

  • Image: Platypus
    Healesville Sanctuary

    From the outside, the platypus looks like a grade-school art project assembled by a kid too busy making spitballs to pay attention in class. The creature, which is classified as a mammal, has a duck's bill and webbed feet, lays eggs like a reptile, but has fur and rears its young on milk.

    Researchers say the platypus genome is equally cobbled together from bird, reptile and mammalian lineages. One more oddity: Males can deliver venom from tiny spurs on each hind limb. Click on the "Next" arrow above to learn about nine more oddballs in the animal world.

    More info: Mixed-up platypus genome unscrambled

    — By John Roach, msnbc.com contributor

  • Colossal squid has plate-sized eye

    AP

    In April 2008, scientists in New Zealand looked a thawing colossal squid in the eye and discovered that the eye is, well, colossal — about the size of a dinner plate. That makes it the largest animal eye on Earth. Fishermen caught the 1,000-pound creature last year in Antarctic waters and froze it intact for scientific study. Colossal squids can reach 46 feet in length and have tentacles equipped with suckers and hooks. Scientists believe the creatures can descend to 6,500 feet and are active, aggressive hunters.

    More info: Huge squid caught, could be biggest ever

  • Aye-aye gives grubs the finger

    Duke University Lemur Center

    The aye-aye is a bushy-tailed primate from Madagascar with big eyes and bat ears. But call it funny-looking and it just might extend its extra-long middle finger in your general direction. The member of the lemur family otherwise uses the extended digit to fish out grubs from the crevices of trees. Captive aye-ayes such as the one shown here from Duke University are teaching scientists about the evolution of color vision.

    Learn more about the brainiac of all lemurs

  • Star-nosed mole sniffs out food, fast

    Image: Star-nosed mole
    Kenneth C. Catania / Vanderbilt

    The fleshy appendages that ring the snout of the star-nosed mole, shown here, make it one strange-looking creature. But when it comes to eating, those 22 tentacles help the mole detect and devour food faster than the human eye can follow — in a fraction of a second. Researchers say the speedy feeding allows the mole to prey on small insect larvae that would otherwise be too energetically costly to eat. The creature lives and forages under the cover of marshes and wetlands along the east coast of North America.

  • Burrowing toad is genetically different

    Robert Puschendorf

    For an amphibian, the stocky and squat Mexican burrowing toad doesn't look all that strange, but it's actually unique. A global conservation program called EDGE of Existence ranks the toad as the most "evolutionarily distinct" amphibian in the world. A fruit bat, polar bear, killer whale, kangaroo and human are all more closely related to one another than the toad is to any other species, according to the program. The Mexican burrowing toad, as its name suggests, spends most of the year underground, coming out only after particularly heavy rains to breed in pools of water.

    Learn about other bizarre amphibians under threat

  • Yeti crab lurks on the ocean bottom

    A Fifis  /  AP

    Named after the legendary shaggy man-beast that tromps through the snows in some of the world's tallest mountains, the Yeti crab blindly scurries about hydrothermal vents along a ridge at the bottom of the Pacific Ocean. First observed in 2005, the crab, officially named Kiwa hirsute, sports a carpet of pale yellow hairs on its arms. Scientists suspect the crab uses those hairs either to farm bacteria or to feel its way around the seafloor for food and potential mates.

    More info: Scientists to list all species on Web

  • Narwhals, the 'unicorn' whales

    Glenn Williams / Harvard Medical School

    Unicorns are purely mythical creatures, but the myths may have been inspired by narwhals. Most males and some females among the 2,200- to 3,500-pound whales sport an 8-foot-long appendage that emerges from the left side of their upper jaw. Scientists recently discovered that the elongated tooth is packed with nerve endings, making it extraordinarily sensitive. The whales may use it to determine the salinity of water and search for food. Male narwhals are also known to rub their tusks together, presumably because it gives off a unique sensation.

    More info: Mystery of 'unicorn' whale solved

  • Sucker-footed bats stick to Madagascar

    Field Museum (left); Bat Conservation Int'l (right)

    In January 2007, scientists announced the discovery of a new species of bat that uses suckers on its thumbs and hind feet to stick to broad-leafed plants such as the traveler's palm. The new species, Myzopoda schliemanni (left image), was found on the dry, western side of the African island nation of Madagascar and is closely related to another sucker-footed bat called Myzopoda aurita (right image) that lives in the humid eastern forests. Conservationists were heartened by the discovery because it suggests the bats can adapt to pioneering broad-leafed plants in deforested areas. Only about 8 percent of the island's original forest cover remains.

    Watch NBC video: What's killing all the bats?

  • Long-eared jerboa hops onto the screen

    Image: Long-eared jerboa
    ZSL

    In December 2007, conservationists released the first known footage of an endangered rodent they've nicknamed the "Mickey Mouse of the Desert." Known more formally as the long-eared jerboa, the little critter has ears about one-third larger than its head, and legs that allow for hopping like a kangaroo. The International Union for Conservation of Nature lists the species as endangered. One threat: the domestic cat.

    More info: Mongolian 'Mickey Mouse' caught on tape

  • Ligers, wholphins and grolar bears, oh my!

    Image: Liger
    TODAY show

    Every now and again, trysts between two different species result in oddball offspring that capture the public's fascination. Ligers, which are a cross between a male lion and a female tiger, were immortalized in the 2004 cult movie "Napoleon Dynamite": The main character of the 2004 cult movie, played by Jon Heder, describes it as "pretty much my favorite animal." (A real one is shown above.) Other popular hybrids include wholphins, which are a cross between false killer whales and Atlantic bottlenose dolphins; and the "grolar bear," a cross between a grizzly bear and polar bear.

    Watch NBC video of a liger
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    Hairy hybrid: Half grizzly, half polar bear

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