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Know the West

Down the wormhole

A Colorado cave might hold a key to extraterrestrial life forms


Name Sulphur Cave (Scientists prefer the "f" spelling, but Sulphur Cave has historically been spelled with a "ph.")

Length 180 feet

Age Sulphur Cave is considered a youngster at an estimated 100,000 years old.

Location Northwest Colorado, near downtown Steamboat Springs, below the jumps of the Howelsen Hill ski area.

Claim to Fame First cave documented in Colorado, in 1843. Now it may be the site of the first hydrogen sulfide-dependent animals ever discovered on land, and a link to learning about life on Mars.

Visit Peek into the cave's upper room as you ski by, but don't go inside. Sulphur Cave contains deadly concentrations of gas, so entry is life-threatening and prohibited.

Last fall, a small team of scientists, veteran cave explorers and a photographer gathered near a small -- and stinky -- opening on Howelsen Hill, on the outskirts of Steamboat Springs, Colo. Giant ventilation pumps whirred, pulling toxic, rotten-egg-smelling hydrogen sulfide and carbon dioxide out of the narrow cave so that the members of the Sulphur Cave Expedition could work their way in. For the fourth time in two years, they braved the drippy acidic atmosphere that burns holes through T-shirts and turns pennies black inside pockets. Undaunted by the slime coating every crevice, the 50-degree chill and the dark cramped spaces, the explorers were in search of something special:  Worms.

Sulphur Cave's dark acidic spring waters hold squirming clumps of blood-red worms unlike any that have ever been discovered on land before. The team first collected the worms during its initial expedition in 2007. After finding them again a year later, one of the team leaders, Norman Pace, a University of Colorado distinguished professor in molecular, cellular and developmental biology, began to suspect their biological significance. He'd previously studied the hydrogen sulfide-eating tubeworms that live along hydrothermal vents at the bottom of the Pacific Ocean. The worms in this cave appeared to be thriving in similarly harsh, acidic conditions.

But it wasn't the worms that first drew scientific attention to Sulphur Cave. Veteran caver Mike Frazier, visiting Steamboat Springs on a ski trip a few years ago, observed snottites hanging inside the narrow entrance -- soft colonies of microorganisms that bear a remarkable resemblance to the gooey nose drippings for which they are named. Snottites are so rare -- there are only four other known occurrences in the world -- that Frazier and his scientific buddies quickly obtained a smattering of university and museum grants and assembled the first Sulphur Cave Expedition.

As the expedition members slithered into Sulphur Cave again last fall, Fred Luiszer, a University of Colorado, Boulder, geologist and speleologist, lurked at the entrance to monitor gas concentrations. He measured hydrogen sulfide at 325 parts per million; the federal standard for maximum daily exposure is 10 parts per million. Carbon dioxide stood at 20.8 percent -- four times the level that will kill you. Team members donned respirators before venturing to the back of the cave.

Photographer Norman Thompson captured Sulphur Cave's beauty -- the intricate masses of biological life on the cave walls that resemble the folds of brain coral; lacy ceiling gypsum crystals that glitter like starbursts; small yellowish stalactites and stalagmites clinging to the walls and floor. Thompson also documented team members squeezing through dark claustrophobic spaces encrusted with biological goo: "It looked like about 10 people had thrown up on them. And that's how they smelled, too."

The team collected more of the pencil-lead-thin worms, and a month later, DNA analysis confirmed their genetic uniqueness. Sulphur Cave's worms may be the first hydrogen-sulfide metabolizing organisms ever discovered on land, where they'll be much easier to study than 14,000 feet below the surface of the ocean. This tiny, often-overlooked cave gives scientists an easily accessible location to learn about the kind of environment, and possibly the organisms, that may exist on Mars or the moons of Jupiter.

"On other planets, those animals are probably going to be bacteria or bacteria-like, and they're probably going to be living in environments similar to this," Luiszer says. "By studying those things here on Earth, it's going to be a lot easier for (scientists) to figure out where to look for life and what kind of equipment and instruments we'll need."

Team member Hazel Barton, costar of the IMAX film Journey Into Amazing Caves, took some of the light-sensitive worms back to her Northern Kentucky University lab for study. She's hoping to determine exactly how the worms, or possibly their bacteria, draw hydrogen sulfide and carbon dioxide from the atmosphere to live on. "This is the only habitat for (these worms)," she says. "The next closest thing is diving two miles to the bottom of the Pacific Ocean. This is a world-class site."