An image of the Martian surface from NASA’s Viking 2
To eke out even the barest subsistence on Mars, a living thing would have to adapt to a formidable set of environmental challenges: an arid, often extremely cold landscape with miniscule amounts of oxygen in the atmosphere and no organic matter to eat. During a recent foray into a similarly inhospitable part of our own planet, scientists have discovered several species of bacteria that hint at what life on Mars, if it exists, might look like. These microbes survive on minerals in the surrounding rocks—minerals also found in the Martian surface.
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A cluster of 3.4 billion-year-old fossilized cells
What’s the News: Geologists have found fossils of microorganisms from 3.4 billion years ago, which may be the oldest fossils ever uncovered. Since these microbes date from a time when Earth’s atmosphere was still oxygen-free, astrobiologists could look for similarly structured microbes when searching for extraterrestrial life.
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E. coli
What’s the News: Some bacteria can live in extreme “hypergravity,” found a new study published in the Proceedings of the National Academy of Sciences, surviving and reproducing in forces 400,000 times greater than what’s felt on Earth. These findings fit with the idea that microbes carried on meteorites or other debris—a ride that would have subjected them to hypergravity-strength forces—may be the ancestors of life on Earth.
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At the bottom of the ice sheet at the bottom of the world lies one of the most pristine and tantalizing places on the Earth—a lake beneath Antarctica that has been isolated for millions of years. Soon, humans will get a glimpse of Lake Vostok.
Since 1990, the Arctic and Antarctic Research Institute [AARI] in St Petersberg in Russia has been drilling through the ice to reach the lake, but fears of contamination of the ecosystem in the lake have stopped the process multiple times, most notably in 1998 when the drills were turned off for almost eight years. Now, the team has satisfied the Antarctic Treaty Secretariat, which safeguards the continent’s environment, that it’s come up with a technique to sample the lake without contaminating it. [Wired]
At about 6,200 square miles, Vostok is nearly the size of Lake Ontario. Its temperature actually remains a few degrees below freezing, but the pressure on the water allows it to stay in liquid form. It’s the isolation, though, that has everyone so excited. There are more than 150 lakes beneath the Antarctic glaciers, but Vostok is the only one that’s entirely cut off.
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First came the extraterrestrial speculation. Then came the actual answer. Then came the backlash.
NASA’s big astrobiology news last week had nothing to do with E.T., of course—the team behind a study in Science announced the find of a kind of bacteria that appear to thrive in arsenic and can even use it in place of phosphorus in the backbone of its DNA double helix. But after the big announcement finally happened and squelched the more imaginative rumors, scientists started asking some hard questions about the study online.
Over at Slate, DISCOVER blogger Carl Zimmer rounded up expert critiques from biologists, and many didn’t hold back.
Almost unanimously, they think the NASA scientists have failed to make their case. “It would be really cool if such a bug existed,” said San Diego State University’s Forest Rohwer, a microbiologist who looks for new species of bacteria and viruses in coral reefs. But, he added, “none of the arguments are very convincing on their own.” That was about as positive as the critics could get. “This paper should not have been published,” said Shelley Copley of the University of Colorado. [Slate]
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The science world is abuzz with news of a strange new life form found in California’s Mono Lake: Researchers report that they’ve discovered a bacterium that can not only thrive in an arsenic-rich environment, it can actually use that arsenic to build its DNA. If the researchers, who published their findings in Science, are correct, then they’ve found a form of life unlike anything we’ve ever seen before.
As you might expect, DISCOVER’s blogs offered plenty of coverage of this exciting news.
At The Loom, Carl Zimmer writes: “Scientists have found a form of life that they claim bends the rules for life as we know it. But they didn’t need to go to another planet to find it. They just had to go to California.”
At Bad Astronomy, Phil Plait explains exactly how the bacteria can make use of arsenic to build their DNA. A few days ago, Phil also took NASA to task for its press release promising news of “an astrobiology finding that will impact the search for evidence of extraterrestrial life,” which fueled wild speculation on whether NASA had found little green men in the solar system.
At Not Exactly Rocket Science, Ed Yong debunks a few of the more breathless accounts. The bacteria do not “belong to a second branch of life on Earth…. They aren’t a parallel branch of life; they’re very much part of the same tree that the rest of us belong to. That doesn’t, however, make them any less extraordinary.”
At Gene Expression, Razib Khan has more thoughts on the wild speculation that preceded the announcement–which he compares to the hype surrounding the unveiling of the Segway.
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At this point, after finding microorganisms that don’t mind extreme temperatures, pressure, aridity and other hardships, we shouldn’t be surprised that bacteria‘s dominion over the Earth extends to just about anywhere we look. A new expedition to the Earth’s crust has reached unprecedented depths—down to the deepest layer of the crust—and found that even there, microorganisms are tough enough to survive.
On a hypothetical journey to the centre of the Earth starting at the sea floor, you would travel through sediment, a layer of basalt, and then hit the gabbroic layer, which lies directly above the mantle. Drilling expeditions have reached this layer before, but as the basalt is difficult to pierce it happens rarely. [New Scientist]
To circumvent the Herculean task of drilling through basalt, the expedition, called the Integrated Ocean Drilling Programme, headed out to sea to find an easier drilling location.
The Integrated Ocean Drilling Program sank its drill into the Atlantis Massif (seen above) in the central Atlantic Ocean where seismic forces have pushed the deep layer, known as the gabbroic layer, to within 230 feet of the ocean floor making it easier to reach. [UPI]
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Want to know what early or extraterrestrial life might look like? You might try looking at Earth’s extremes: the coldest, highest, and deepest places on our planet. One unmanned research vehicle just tried the last of these strategies, and took samples from a hydrothermal vent plume 16,000 feet under the sea–about 2,000 feet deeper than the previous record-holding vent.
A research team led by Woods Hole Oceanographic Institution (WHOI) and including scientists at NASA’s Jet Propulsion Laboratory studied three hydrothermal vents, found along an underwater ridge in the Caribbean called the Mid-Cayman Rise. They published their findings yesterday in The Proceedings of the National Academy of Sciences.
Hydrothermal vents are usually found in spots where the Earth’s tectonic are moving away from each other, creating a weird zone of raw chemistry. A mixture of hot vent fluids and cold deep-ocean water form plumes, which can contain dissolved chemicals, minerals, and microbes. Instead of searching the entire 60-mile-long ridge with the vehicle, the team scouted for chemicals from the plume to zero-in on the vents.
“Every time you get a hydrothermal system, it’s wet and hot, and you get water and rocks interacting. Wherever this happens on the seafloor, life takes advantage,” said geophysicist Chris German of the Woods Hole Oceanographic Institute. “Every time you find seawater interacting with volcanic rock, there’s weird and wonderful life associated with it.” [Wired]
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Extremophiles microbes: They’re tougher than you. Scientists have found microorganisms living in the ultra-dry Atacama desert, Antarctica, volcanic hot springs, and now, lakes of asphalt.
Trinidad, the larger island of the Caribbean duo Trinidad and Tobago, is home to Pitch Lake. This 100-acre pool of hot liquid asphalt is the largest of its kind on our planet, but microbiologist Steven Hallam thought it could tell us something about another world: the Saturnian moon of Titan. If anything could live in the toxic stew of Lake Pitch, he thought, perhaps there’s hope for the hydrocarbon lakes and rivers of that distant moon. He found that the earthly lake teems with life. “Water is scarce in the lake and certainly below the levels normally thought of as a threshold for life to exist,” he says. “Yet on average, each gram of ‘goo’ in the lake contains tens of millions of living cells” [Australian Broadcasting Corporation].
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Microorganisms can live the far reaches of the planet, in extreme temperatures and pressures, and in some cases even without oxygen. But now scientists say they have found the first multicellular organisms inhabiting an anoxic environment. In other words: They’ve found the first animals living without oxygen.
They belong to the group called loriciferans, a phylum of creatures that live in marine sediment. About a millimeter long, they look something like a half-jellyfish, half-crab. The beasts live in conditions that would kill every other known animal. As well as lacking oxygen, the sediments are choked with salt and swamped with hydrogen sulphide gas [New Scientist].
Roberto Danovaro and his colleagues, who documented this find in BMC Biology, had been searching the salty, oxygen-free depths of the Mediterranean Sea down below 10,000 feet for life. When previous searches turned up animal bodies, he says, researchers wrote them off, thinking they had fallen to those depths from oxygenated waters closer to the surface. But Danovaro says his team recovered living loriciferans from the area, including ones with eggs.
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The next generation of bulletproof vests and military armor could well be inspired by a deep-sea snail, say scientists.
A team led by materials scientist Christine Ortiz of the Massachusetts Institute of Technology investigated the iron-rich shell of the “scaly foot” mollusk, whose triple-layered shell gives it one of the strongest exoskeletons seen in nature. The researchers believe that copying its microstructure could help in the development of armor for soldiers, tanks, and helicopters. Their work was published (pdf) this week in the Proceedings of the National Academy of Sciences.
Scientists were first drawn to this snail in 2003 when they discovered it living in a relatively harsh environment on the floor of the Indian Ocean. It lives near hydrothermal vents that spew hot water–thereby exposing it to fluctuations in temperature as well as high acidity. It also faces attacks from predators like crabs and other snail species. But unlike other snail species, this snail survives because of its thick shell and the different properties of each of its three layers.
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After 120,000 years of slumbering in a Greenland glacier beneath almost two miles of ice, an ultra-small bacteria has been resurrected by the patient efforts of scientists. After incubating the bacteria for almost a year in water that was just above freezing temperature, colonies of the tiny purple-brown bacteria began to grow in a petri dish. Researchers say the bacteria’s resilience provides clues to how life can survive in hostile environments like the Arctic–and maybe even other planets.
The Herminiimonas glaciei bug is not the oldest to ever be resurrected, but it’s the first “ultramicrobacteria” to be revived. Ultramicrobacteria, tiny even by bacterial standards, are about 10 to 50 times smaller than the common human intestinal microbe E. coli. Their diminutive size could give the bacteria a survival advantage over other microorganisms. H. glaciei, for example, is thought to have survived in thin capillaries of nutrient-rich water in the Greenland glacier that would have been too tight a fit for larger bacteria [National Geographic News].
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Life sure turns up in the darnedest places. The latest discovery comes from Blood Falls, a rusty red discolouration on the face of the Taylor Glacier in Antarctica [that] occasionally gushes forth a transparent, briny, iron-rich liquid that quickly oxidizes and turns red, staining the ice below [Nature News].
The source of that water is an intensely salty lake trapped beneath 1,300 feet of ice, and a new study has now found that microbes have carved out a niche for themselves in that inhospitable environment, living on sulfur and iron compounds. The bacteria colony has been isolated there for about 1.5 million years, researchers say, ever since the glacier rolled over the lake and created a cold, dark, oxygen-poor ecosystem.
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Almost two miles beneath the earth’s surface in a South African goldmine, researchers have found a new species of bacteria that lives in total isolation from any other organism. The discovery offers the first known example of an ecosystem that isn’t a complex web of different life forms, but is instead hosts just one self-sufficient species. The bacteria, Desulforudis audaxviator, is able to extract all its food and energy directly from the surrounding water and rocks, and researchers say the independent microbe offers a glimpse of the shape life could take on other planets.
Researchers wanted to know what organisms were living in the mine’s deep fissures, a habitat completely devoid of light and oxygen, so they analyzed the genes present in a water sample to determine what species lived there. They filtered a total of 5,600 liters of mine water to get their sample, which gave other microbes plenty of opportunities to make themselves known. Of the DNA sequences obtained from this sample, over 99.9 percent were from this single species; over half of the remainder were obvious contaminants from their own lab [Ars Technica].
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Marine biologists have gotten the first footage ever of a school of fish living 4.8 miles beneath the ocean‘s surface in the cold, pitch black, and fiercely pressurized habitat of the Pacific’s Japan Trench. A video shows the pale white hadal snailfish, officially known as Pseudoliparis amblystomopsis, happily wriggling around on the seabed, despite water pressure that the researchers say is equivalent to 1,600 elephants standing on the roof of a Mini.
The fish belong to a species previously known only from five pickled specimens trawled up by Russian scientists in the 1950s, said [researcher] Monty Priede [National Geographic News]. Priede’s team of British and Japanese researchers found the rare snailfish during their exploration of deep, narrow marine trenches in Pacific Ocean, and say it was the deepest ever sighting of live fish.
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