by Barbara Arnstein

Five and a half million years ago, when humans were just getting started, limestone plummeted onto the entrance of a cave, trapping dozens of types of insects and arthropods in pitch-darkness. Over time, the stifling air became worse and worse until it eventually contained one hundred times as much carbon dioxide as the atmosphere outside it.. Yet the unlucky creatures stuck in it didn't die. They evolved, thrive and multiplied. As time caused their eyes to dwindle and disappear, their blindness was balanced by developing extra-long antennae and super-long legs to grope their way through life. Many developed their skill at detecting electrical emanations, to more easily capture their prey. Most importantly, the cave became the only ecosystem on Earth that relies on chemosynthesis, the ability (you could call it a super-power!) to derive energy from the oxidation of chemical compounds rather than from the sun (photosynthesis). In other words, although trapped in stinky caverns reeking of sulfur and ammonia, exactly like the classic depiction of Hell, they rose above the situation.

Without sunlight to stimulate the pigments that create colors on living creatures, their bodies became translucent or clear. Most incredibly, an ecosystem unlike any other on Earth fell into place. Only in this cave does breathing center around chemosynthesis, getting oxygen from oxidizing minerals, rather than photosynthesis, the way plants create oxygen from sunlight. The chemicals come from the sulfuric acid, methane and ammonia that stink up the place like rotten eggs.

In 1986, workers seeking a good spot to build a geothermal power plant stumbled on the cave in Constanta, Romania, known as Movile (pronounced Mo-veel-a) Cave, one of the greatest scientific discoveries of the twentieth century .Of the four dozen species inhabiting it, thirty-three were unknown to science, including the world's only known cave-adapted water scorpion. Its other inhabitants include spiders, worms, snails, cockroaches, leeches, and centipedes. Humans who visit need to bring not only a gas mask and an oxygen tank but also great confidence about their sense of direction squeezing through its narrow passageways and underwater tunnels because getting lost could be lethal,

LIKE MANNA IN THE DESERT Manna is the food in a Bible story miraculously supplied to people wandering in the desert. In Movile Cave, the manna is a frothy foam composed of billions of bacteria called autotrophs blanketing its walls. Luckily for the cave residents, it's the reliable bottom rung of their food chain Those bacteria feed bigger bacteria, which nourishes snails, worms and shrimps and such, which in turn serve as food for the spiders, scorpions and leeches. Although there are no flies in the cave, spiders spin webs out of habit, which catch insects called springtails that leap up and land in their sticky strands, becoming lunch. HOW TO FEND OFF RADIATION One thing that makes it completely different from most other caves is that its water arises from spongy sandstone, not an outside source. Scientists figured this out after finding that traces of radiation from the Chernobyl nuclear accident were present in the water and soil surrounding it but not within it. Cristian Lascau, the first cave expert to explore its depths, commented that if the planet were to be devastated by a nuclear war, it would survive thanks to the thick layers of clay shielding above it.

CARE TO VACATION THERE? If you're dying to pay a visit there, it won't be easy. First of all, you now have to have really good scientific credentials, for example, as a career cave explorer, or, even better, as a researcher at NASA. They don't let just anyone in, ironically because their intrusion might disrupt the delicate balance of life in the cave. Next, you have to travel to a featureless plain in the middle of nowhere, and then comes the really fun part: descending about seventy feet into the humid, stifling caverns, before making your way through the claustrophobic tunnels. The good news is that the worse the air becomes, the more creatures you'll see...and feel, scuttling and slithering all around you.

EARTH'S MARTIANS NASA considers the creatures in the cave so unusual that they've nicknamed its lake areas "Underwater Mars". The "alien species" include a whole new type of centipede and a leech, three spiders, and four isopods, The one they dubbed "The King of the Cave" because, at two inches long, it's the longest bug there, is a venomous centipede. HOPE FOR THE FUTURE Lascau believes that that finding life thriving in such conditions proves that we could possibly detect life on other planets in environments previously considered uninhabitable. The amazing way life continues in a place so thick with toxic gases gives scientists hope that humans can better adapt to pollution.