SMALL Game Hunters

Why would anyone risk life and limb plunging 11,000 feet beneath the ocean's surface, or camping out in the Antarctic cold for weeks at a time, or nosing around a pitch-black underground cave? Scientists who work in these extreme environments hope to discover new forms of life on earth, and perhaps beyond.

Pleased to Meet You

New life forms here on earth? Yes, but don't run to your local zoo to see them. Get out your microscope instead. Since the 1960s, scientists have been discovering remarkable new forms of microscopic life in the most unlikely places: superhot, deep ocean springs; freezing cold polar ice; and dark, damp, poisonous caves. Some of these tiny creatures are bacteria; others are called archaea, which is Greek for "ancient." Experts believe that these archaea may closely resemble the first life forms that appeared on earth 3.5 billion years ago.

Lifestyles of the Small and Extreme

Scientists call these tiny creatures extremophiles, or "lovers of extremes." Until recently, no one believed that life could survive under such conditions. But scientists are quickly changing minds as their research takes them to corners of the planet that no one has ever seen before. Indeed, the hardest part about studying this small game is finding it, collecting it, and then bringing it back to the lab. It takes curiosity, bravery, patience, a love of adventure, and, sometimes, a good sense of humor to be a small game hunter.

To Boldly Go

Until recently we knew more about the surface of the moon than about the bottom of the ocean. Lately, however, oceanographers have been spending a lot of time deep beneath the waves, discovering an amazing new world. Two miles down, where no sunlight can reach, under crushing water pressure, researchers expected to find a dark, dreary underwater desert. But in 1979, a team of scientists exploring the sea floor off the coast of South America in the submersible Alvin came across something incredible: a tall rock "chimney" spewing black liquid. Even though the rush of fluid knocked the little sub around, using Alvin's mechanical arm, the scientists managed to plunge a temperature probe into the dark cloud. It was so hot that the instrument melted! If Alvin had been closer, its plastic portholes would have melted, too.

The team had discovered the first "black smoker," blowing out superheated gases and minerals from inside the earth through "leaks" in the ocean floor. With a sturdier thermometer, the team measured the temperature of the strange substance at 662 degrees Fahrenheit. (Your bath water is probably about 100 degrees Fahrenheit.) Also called hydrothermal vents, the hot, mineral-rich chimneys can support an entire community-clams, mussels, tubeworms-where scientists once believed no life could exist. But the most important, and remarkable, inhabitants of the vents are the extremophiles that dwell there. Called thermophiles, or "heat lovers," they live in water hotter than boiling, and they breathe sulfide, methane, iron oxide, and hydrogen. Because they make wonderful meals for other dwellers of the deepest darkest ocean, the extremophiles keep the whole colorful colony alive. "The discovery of hydrothermal vent life completely rearranged our thinking about where and how life could exist on earth-and possibly on other planetary bodies," observed biologist Tim Shank, of Woods Hole Oceanographic Institute.

To Coldly Go

The trail of the extremophiles leads from superhot to bitter cold. In Antarctica, teams of researchers are finding extraordinary microscopic life inside the ice. They call these tiny creatures psychrophiles, which means "cold lovers."

Parts of Antarctica's Dry Valleys look more like a rocky desert than a polar region. But don't be fooled; the temperature there hovers around -22 degrees Fahrenheit year round. Several permanently frozen lakes dot the landscape, including Lake Vida, three miles long and frozen solid. Scientists once thought Vida was frozen through to the bottom, but in 1996 a team of researchers discovered that under 62 feet of ice there lay a salty, unfrozen liquid "lake" that had been undisturbed for at least 2,800 years.

Peter Doran, a polar scientist from the University of Illinois, and his team used drills to pull out long cores of ice to study dirt and other substances frozen over the centuries. "It was some very cold drilling. We were there for two weeks at temperatures approaching -40 degrees Fahrenheit-camping."

What they found surprised them: extremophiles that could freeze and thaw year after year. Once in the lab, the scientists were able to revive the tiny life forms from their frozen state. Based on their dating of the ice, these microbes could be nearly 3,000 years old and still kicking!

But that still leaves the mystery of the under-ice lake. Field researchers were reluctant to drill all the way through the ice into the liquid for fear of contaminating its purity. They stopped just about three feet above the liquid's surface. They are now busy trying to figure out how to get samples without introducing any foreign substances that might pollute the ancient liquid. Once they do, they hope to be able to learn more about life's beginnings.

Small, But Powerful

Extremophiles aren't just for studying. Researchers are discovering how they can come in handy. Like other living things, they contain proteins known as enzymes. We use enzymes to make cleaning materials and cosmetics and to process and preserve food. When they come from extremophiles, they are called "extremozymes." (Now that's original.) Because they live in intense heat, cold, and other extremes, extremozymes can survive harsh conditions in industry and in the laboratory. They are used to fade the jeans you buy. They make certain types of medical research possible. Cold-loving extremozymes can help crops survive freezes. Others can break down toxic waste to clean up oil and chemical spills.

Slime-Me

OK, just when you thought you'd reached the corners of the earth, how about this? A cave with very little oxygen but filled with toxic fumes, slime, bats, darkness, and, you guessed it, extremophiles.

Cave Villa Luz, deep in the Mexican jungle, brims with hydrogen sulfide, which gives it a poisonous atmosphere and a smell like rotten eggs. But caver and geologist Louise Hose still loves Villa Luz because it is CRAWLING with life. Many known caves are "dead,"so Hose calls Villa Luz a "world-class natural laboratory" and has made many research trips into its dark depths. Slimy mats of microbes literally line the walls of Villa Luz. They are so thick that they drip from the ceilings in formations Hose calls "snottites," for obvious reasons. To find extremophiles, Hose and her team sample red goo and green slime and long, stringy weblike material. Like other extremophiles, these cave dwellers thrive on hydrogen sulfide (sort of like battery acid), they live without sunlight, and they form the basis of a flourishing ecosystem deep in the cave.

Scientists who brave these caves must wear special gas masks and protective clothing. Too long a time underground can mean getting lost, getting sick, or getting hurt, yet researchers spend six or more days squeezing in and out of narrow passageways and wading through poisonous water as they hunt, study, and collect their small game.

So What? Buy why the fuss? Who cares about all this microscopic life?

Some experts now believe that extremophiles may have been the first forms of life to appear on earth billions of years ago. Could that be true elsewhere in the universe? Europa, one of Jupiter's moons, shows evidence of hydrothermal activity under its icy covering. Mars may have once had underground lakes. Toxic gases, much like the atmosphere deep in our caves, blanket planets and moons throughout the solar system. Someday, perhaps, scientists will find life in those extreme environments, too.

Copyright Carus Publishing Company Mar 2004
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