Joseph Russell / University of Delaware

The Joides Resolution heads to sea from the Azores to drill sediments on IODP Expedition 339 offshore Peru. Most of the Earth's organic carbon is stored in seafloor sediments.

By Douglas Main
LiveScience

Beneath the seafloor lives a vast and diverse array of microbes, chomping on carbon that constantly rains down from above and is continually buried by a never-ending downpour of debris — some whale dung here, some dead plankton there. For the first time, a study has shown that these microbes are actively multiplying and likely even moving around in the compressed, oxygen-devoid darkness beneath the abyss.

The finding, detailed in Wednesday's issue of the journal Nature, is important because the sediments below the seafloor harbor most of the Earth's organic carbon, as well a majority of its microorganisms, according to various scientific estimates. These microbes also play a vital but little-understood role in the cycle of carbon between the ocean and the seafloor, which impacts the entire Earth's climate.

The study is the first to directly show these microbes are alive and kicking, said study team member William Orsi, a researcher at the Horn Point Lab at the University of Maryland. Previously, it had "been debated in the community whether they are in a dormant state or whether they're alive and active," Orsi told LiveScience's OurAmazingPlanet. Clearly, the latter is the case, he said.

Breathing sulfate
Studies of this region, the so-called deep biosphere, have heretofore relied on DNA samples. This research has revealed many types of cells, but cannot prove whether or not they're alive. The new study looked at genes that are actively expressed, or made into proteins, meaning that the cells of interest are currently living, Orsi said.

The study examined the metabolic processes of all these microbes — what they eat, and how they breathe. His team found an astonishing variety of this microscopic life was present in the seafloor soils. Many appear to "breathe" sulfate and chomp on organic matter, emitting carbon dioxide into the soil, Orsi said. At the same time, others can feed upon and fix this carbon dioxide, in a process similar to photosynthesis (the process that powers plants), but that happens in complete darkness. [Strangest Places Where Life Is Found on Earth]

"Much of this carbon dioxide is probably getting assimilated before it reaches the ocean, but we don't know how much," Orsi said. That's important, because the degree to which these microbes fix or emit carbon dioxide from the ocean, and ultimately the atmosphere, will have a big impact on Earth's climate, he added.

Swimming through sediment
Some of the highest cell counts the study found correspond to the largest production of proteins involved in cellular division, meaning life is proliferating at depth, said Steven D'Hondt, a researcher at the University of Rhode Island who has studied the deep biosphere but wasn't involved in this study. The most activity occurs where methane from below and sulfate from organic matter raining down from above come together, D'Hondt said. The microbes breathe using sulfate and break down methane to provide themselves with energy, he added.

Others breathe using nitrate, manganese and iron. "It's pretty incredible," Orsi said. Although these chemicals allow cells to survive, they don't provide as much energy as oxygen. So cellular processes persist, but "happen a lot slower" than in most types of life that scientists have investigated, Orsi said. 

Somehow, though, they have enough energy to move about. Orsi's team found abundant evidence that some types of microbes are producing flagella, the tail-like appendages that allow them to "swim" through the sediment, D'Hondt said.

The seafloor sediment samples were taken off the coast of Peru from a ship called the Joides Resolution as part of the Integrated Ocean Drilling Program, which grants researchers access to ships that can drill into the ocean bottom. The sediment comes from up to 520 feet (159 meters) beneath the seafloor surface.

Buried fungi
The study found a large amount of archaea, single-celled life-forms in a separate kingdom of life from bacteria. The research also revealed a thriving community of fungi beneath the seafloor: About 10 percent of the total genes were fungal genes. "That's a third domain of life that's active down there that people hadn't considered. When you walk through a forest, it's obvious how important fungi are," Orsi said. "Similar processes are also happening here."

When Orsi first applied for funding for the type of genetic analysis used in this study, "the panel that reviewed it basically said that that's not possible because the cells aren't active enough," he said. But he tinkered with the existing technique and proved them wrong.

Recently, scientists have lowered their estimates of the number of microbes that they expect live deep underground. One landmark study from 15 years ago estimated that subseafloor sediments contain 35.5 x 10^29 microbes (that's 1 followed by 29 zeroes). But a follow-up study published Aug. 27 in the journal Proceedings of the National Academy of Sciences estimates that there are a mere 4.1 x 10^29 microbes under the sea, about eight times less than previously thought.

Email Douglas Main or follow him on Twitter or Google+. Follow us @livescience, Facebook or Google+. Article originally on LiveScience.com.

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Woods Hole Oceanographic Institution

A. fulgidus microbes, which are found in extremely hot hydrothermal vents, can use perchlorate, an ingredient in rocket fuel, for energy.

By Jesse Emspak
LiveScience

An ancient form of life can use an ingredient in rocket fuel for energy, suggesting creatures with this odd ability are more diverse than anyone thought.

The new discovery might offer insight into the history of life on the early Earth, and the evolution of metabolisms like ours that use reactive chemicals like oxygen.

Called Archaeoglobus fulgidus, today the microbe lives in extreme environments, such as extremely hot hydrothermal vents. It's a member of the Archaea, one of the three domains of life. (The other domains are bacteria, or prokaryotes, and creatures with cells that have nuclei, or eukaryotes, which include humans and other multicellular life.) Archaeans are some of the oldest life forms on Earth, thought to have appeared at least 2.7 billion years ago – and they are possibly much older than that. They often live in environments that don't have oxygen or are otherwise inhospitable to many other living things.

A group of Dutch researchers found that A. fulgidus metabolizes perchlorate, a chlorine atom connected to four oxygen atoms. Moreover, the microbe does so in a different way than known Archaea or bacteria do – A. fulgidus is missing one of the enzymes other bacteria use to break down perchlorate. [In Photos: Archaea Turn Great Salt Lake Pink]

Toxic Earth
When combined with potassium, perchlorate is used as an ingredient in fireworks and, when combined with ammonium, as an ingredient in rocket fuel. But it also occurs naturally, in deserts such as the Atacama in Chile, and may have been more plentiful on early Earth and even on Mars. Recently, the Curiosity rover found possible evidence of perchlorates in Rocknest – a patch of sand in Mars’ Gale Crater – suggesting the compound may exist all over the Red Planet.

Since A. fulgidus is an early-Earth organism, the researchers suspect that perchlorate was also around at that time and that the ability to metabolize it was part of an adaptation to all sorts of highly toxic chemicals, many of which are oxidizers. An oxidizer takes electrons away from other molecules. Such chemicals tend to be fairly toxic to many microbes because they disrupt their metabolisms or cell walls. 

"The use of perchlorate by early ancestral microbes might thus have been one of the first entries of highly oxidative compounds in the microbial metabolism, probably even before photosynthesis evolved," said Martin Liebensteiner, a doctoral student at the Wageningen University Laboratory of Microbiology in the Netherlands and lead author of the study, detailed this week in the journal Science.

Oxygen is another oxidizer (hence the name), and a highly reactive one at that. Before plants evolved, there wasn't any in the atmosphere. In fact, oxygen is so reactive that it can kill some types of Archaean life and many bacteria. Living things had to adapt to using such chemicals, or nothing else would have survived once plants' ancestors, cyanobacteria, started dumping oxygen into the air en masse. Humans' mitochondria are the legacy of that adaptation, which involved incorporating oxygen-using cells into other life forms, allowing them to tolerate the new atmosphere. The findings here might be suggesting other strategies for using oxidizing chemicals that were around before that happened.

Microbe's perchlorate-eating ways
Other bacteria that can breathe and eat perchlorates use a two-step process involving specialized enzymes that turn perchlorate into chlorite – which has two, rather than four, oxygen atoms – and then separate the chlorite into chlorine and oxygen.

A. fulgidus doesn't do that, Liebensteiner and his colleagues found. Whereas it uses an enzyme similar to that of known bacteria to perform the first step, it doesn't have the enzyme that breaks up the chlorite. Instead, A. fulgidus' metabolism uses sulfur compounds called sulfides, in a reaction that isn't controlled by any enzyme but occurs naturally between the two sets of chemicals.

The sulfides (negatively charged sulfur atoms) react with the chlorite to make more highly oxidized sulfur compounds, like sulfate and chlorine, by separating the oxygen from the chlorine and adding oxygen atoms to the sulfide.

This has an added bonus for the tiny creature: It can generate energy by using the sulfur compounds, and using that energy makes more sulfide. As the sulfide gets "recycled," it can react with more chlorite molecules released from the reaction that break up the perchlorate.

"It seems as if A. fulgidus relies on the interaction of these abiotic and biotic reactions in order to grow with perchlorate," Liebensteiner wrote in an email to LiveScience.

One other feature of A. fulgidus is that it lives in hot, high-pressure environments without oxygen. The creature was discovered in an underwater volcanic vent and is happy at temperatures near the boiling point of water, between 140 and 203 degrees Fahrenheit (60 to 95 degrees Celsius). That's a lot like the conditions on Earth more than 2.5 billion years ago, when the planet’s atmosphere had no oxygen because plants hadn't yet evolved. In addition, volcanic activity was much more intense. [The 7 Harshest Environments on Earth]

Why retain this ability?
Robert Nerenberg, an associate professor of environmental engineering who has studied perchlorate-metabolizing bacteria, noted that A. fulgidus metabolizes perchlorate only when it is in an environment where only sulfur is present. The research team did that in order to remove any oxygen from the environment, but the interesting thing, Nerenberg said, is that in the presence of chlorates the bacteria metabolize those instead of perchlorates. (Chlorate is perchlorate with one less oxygen atom). So A. fulgidus' "preference" may not be for perchlorate.

The question, he said, is why any creature — bacteria or archaean — would retain an ability to metabolize perchlorate after billions of years when it might not need to. "Usually certain genes just sort of stop working after a while if there's no selective pressure for them," he said. "There has to be some benefit." What that is, though, is a bit of a mystery.

Liebensteiner said he didn't want to speculate too much about what this means for evolution billions of years ago, because the evidence isn’t yet sufficient. Other scientists, he noted, have shown that in places where perchlorates form naturally, such as deserts, perchlorate would tend to accumulate because perchlorate is relatively stable (i.e., absent the action of the enzyme in bacteria and archaeans, it doesn't react with anything without adding a lot of heat). But it hasn't stuck around.

"That's the point where people start getting thoughts that because of bacterial activity, (the perchlorate) didn't accumulate," Liebensteiner said.

And the fact that A. fulgidus has a pathway for breaking down perchlorate that is similar to known bacteria, but lacking one enzyme suggests that, at a minimum, there are several ways to evolve perchlorate metabolism — either spontaneously or via gene transfer, which can happen among single-celled life forms.

More work is needed to see if this same kind of metabolism occurs in other Archaeans, and even in bacteria. "It definitely means that (A. fulgidus) is probably more diverse than people thought," he said.

Follow us @livescience, Facebook and Google+. Original article on LiveScience.com.

• Extreme Life on Earth: 8 Bizarre Creatures
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University of British Columbia

While Cthulhu macrofasciculumque isn't as frightening as Lovecraft's Cthulhu, it does look like it has a big tuft of tentacles.

By Megan Gannon
LiveScience

Scientists have discovered two new species of strange-looking microbes that live in the bellies of termites, and they've named the creatures Cthulhu and Cthylla, an ode to H.P. Lovecraft's pantheon of horrible monsters.

Even though Lovecraft said the mere existence of Cthulhu was beyond human comprehension, the 20th-century American sci-fi author described the ocean-dwelling creature as vaguely anthropomorphic, but with an octopus-like head, a face full of feelers and a scaly, rubbery, bloated body with claws and narrow wings.

The microbe Cthulhu macrofasciculumque doesn't appear quite as frightful under a microscope, but it does have a bundle of more than 20 flagella that resembles a tuft of tentacles beating in sync.

"When we first saw them under the microscope they had this unique motion, it looked almost like an octopus swimming," researcher Erick James of the University of British Columbia said in a statement. [See Image of the Squiggly Lovecrafter Monsters]

Cthylla microfasciculumque, meanwhile, is smaller sporting just five flagella, and is named for the Cthylla, the secret daughter of Cthulhu, generally portrayed as a winged cephalopod. Cthylla was not a creation of Lovecraft, but rather British writer Brian Lumley, who added to the "Cthulhu Mythos" in the 1970s.

 The little protists, smaller than a tenth of a millimeter, are part the rich community of gut microbes that help termites turn wood into digestible sugar (which is why the pests can eat up the walls of a home fairly quickly).

"The huge diversity of microbial organisms is a completely untapped resource," said James. "Studying protists can tell us about the evolution of organisms. Some protists cause diseases, but others live in symbiotic relationships, like these flagellates in the intestines of termites."

James and colleagues published their findings online March 18 in the journal PLOS ONE.

If you're curious about how to say the names of the newfound creatures out loud, the researchers note that Lovecraft gave different pronunciations for Cthulhu because the name was supposed to come from an alien language, impossible for the human vocal capacity to mimic. "Ke-thoo-loo" is thought to be the safe approximation for Cthulhu, whereas Cthylla is often pronounced "ke-thil-a."

Follow Megan Gannon on Twitter and Google+. Follow us @livescience, Facebook and Google+. Original article on LiveScience.com.

• Extreme Life on Earth: 8 Bizarre Creatures
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Rocky Mountain Laboratories, NIAID, NIH

Professors at the Microbial Evolutionary Ecology at the University of Zürich investigated the suicidal behavior of E. coli cells (above).

By Jennifer Viegas
Discovery News

A study on suicidal E. coli sheds light on why organisms throughout the animal kingdom, big and small, sometimes decide to do themselves in.

The good news is that suicide appears to be comparatively rare in larger animals, but more common among microscopic life forms, such as microbes, according to the study, published in the latest Proceedings of the Royal Society B.

Natural selection -- the process by which organisms that adapt to their environment tend to survive and produce more offspring -- favors suicide when the death guarantees the survival of relatives and the individual is less likely to reproduce in future.

NEWS: Is Suicide Contagious?

An example of this, according to study co-author Rolf Kümmerli, is when "a parent saves his children out of a burning house. This is beneficial because the rescued relatives share many of the genes with the suicidal helper." Many people are driven to save their kids and close loved ones, no matter what.

Other forms of suicide among humans, such as bombers on a kamikaze mission, likely have nothing to do with natural selection, and instead reflect the by-product of something else. In the case of the bomber, that could be the individual's environment and life’s experiences. Depression or other forms of mental illness, however, could be inherited.

Kümmerli, a professor in the department of Microbial Evolutionary Ecology at the University of Zürich, and colleagues Dominik Refardt and Tobias Bergmiller investigated the suicidal behavior of E. coli. Some cells of this common bacteria will kill themselves in the presence of bacteria-killing parasitic viruses.

NEWS: Assisted Suicide: Legalize It?

Rolf Kummerli

A 250-fold magnification of two E. coli colonies. The phage could eat holes into the colony of a susceptible strain (left bottom), whereas colonies of the suicidal strain remain unharmed (upper right).

Kümmerli explained to Discovery News that when a protein of an E. coli cell senses viral attack, it becomes activated and, with other proteins, triggers drainage of membrane holes of the bacterial cell. It’s as though the cell biochemically stabs itself.

"Consequently, vital cell liquid and components pour out into the environment, which leads to cell death," he said. "The dead cell is presumably like an empty perforated sack."

Even among lowly microbes, such behavior would seem to go against survival and procreation mechanisms. Behaviors that benefit others, at the expense of the individual, however, can emerge when multiple relatives are saved. They can also emerge to benefit unrelated others when the cost of suicide is low.

In the case of E. coli cells, they would likely die from the viral attack anyway, and their death prevents parasite transmission to nearby other E. coli cells.

Suicide is also well documented in social insects that tend to live in large populations, such as ants and bees. Some ants will even explode themselves to prevent intruders from attacking their relatives.

NEWS: Microbes Thrive in Deepest Spot on Earth

Suicides among non-human mammals and other larger animals are mostly anecdotal, but they do tend to once again apply to social species, such as dogs and dolphins. Dolphin trainer Ric O'Barry, for example, claimed that he watched the famous TV star dolphin, Flipper, take her own life out of sheer depression due to confinement in captivity. O'Barry later became an animal activist.

Gaining a better understanding of the drivers behind suicide could lead to life-saving benefits. Researchers in future might be able to coax harmful bacteria, viruses and other microbial organisms to kill themselves, potentially saving human and other animal lives.

Stuart West, a professor of evolutionary biology at the University of Oxford, commended the new research, saying the researchers "show here that if the costs of suicide are low (the individual is unlikely to reproduce anyway), then relatedness doesn't have to be very high, although it does have to be above zero."

Anni Glud

The central part of the autonomous instrument that was deployed to measure the oxygen dynamics of the sea-bed in the Mariana Trench at a depth of 11 km. Data documented intensified microbial life in the bottom of the trench as compared to conditions at the surrounding abyssal plains at 6 km water depth.

By Charles Q. Choi, OurAmazingPlanet 

The deepest oceanic trench on Earth is home to a surprisingly active community of bacteria, suggesting other trenches may be hotspots of microbial life, researchers say.

Life in the deep ocean often relies on organic matter snowing down from above. As these particles waft down, their nutrients get degraded by microbes attached to them, so only 1 to 2 percent of the organic matter produced in surface waters is expected to make it to the average ocean depth of about 12,150 feet (3,700 meters). Just how much makes it to the very deepest parts is unknown.

To learn more about life in the dirt at the ocean's depths, scientists used a submersible lander to analyze mud from the surface of Challenger Deep, the deepest spot of the Mariana Trench at the bottom of the central west Pacific Ocean. This 36,000-foot-deep (11,000 m) trench is the deepest known point on Earth's surface.

Natural trap
The researchers analyzed the levels of oxygen consumption within the sediments, which revealed how active the deep-sea microbes were. They discovered unexpectedly high rates of oxygen consumption from the Mariana seafloor, indicating a microbial community twice as active as that of a nearby 19,700-foot (6,000 m) site about 35 miles to the south. [Strangest Places Where Life Is Found on Earth]

"In the most remote, inhospitable places, you can actually have higher activity than their surroundings," researcher Ronnie Glud, a biogeochemist at the Southern Danish University in Odense, Denmark, told OurAmazingPlanet.

Sediments from Challenger Deep also had significantly higher levels of microbes and organic compounds than the nearby, more elevated site. The investigators suggest the Mariana Trench acts as a natural trap for sediments from up high. Similar effects are seen in other submarine canyons.

"It acts as a trap just because it's a big hole. If you have a hole in a garden, it just fills up because things blowing over it tend to fall in, and the same is true with the seafloor," Glud said. The trench is also located in a subduction zone where one of the tectonic plates making up the surface of the Earth is diving under another, "and these areas are very unstable, and frequently see earthquakes that can trigger mudslides that transport material into the trench," he added.

Microbes, microbes everywhere
Another team of scientists recently discovered communities of microbes thriving in the oceanic crust. That research looked at rocks up to about 1,150 to 1,900 feet (350 to 580 m) below the seafloor under about 8,500 feet (2,600 m)  of water off the coast of the northwestern United States. These microbes apparently live off energy from chemical reactions between water and rock instead of nutrients snowing from above.

"You can find microbes everywhere — they're extremely adaptable to conditions, and survive wherever they are," Glud said.

The researchers are now analyzing other trenches to see what bacterial activity is also relatively high there. They also want to learn more about the genetics of bacteria in the Mariana Trench and other trenches "to see how special these bacteria are compared to other bacteria," Glud said.

The scientists detailed their findings online March 17 in the journal Nature Geoscience.

Follow OurAmazingPlanet @OAPlanet, Facebook and Google+.Original article at LiveScience's OurAmazingPlanet.

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By Tanya Lewis
LiveScience

As far back as we know, animals have been home to microbes. Scientists have known for some time that these tiny tenants have the ability to make humans powerfully sick, while others are vital to maintaining the body's normal flora and fauna.

Collectively, the microbes inside everyone make up the "microbiome" — what microbiologist Martin Blaser of the NYU School of Medicine defines as "all the organisms that call us home, that live in us and that interact with each other and with ourselves."

These teensy creatures, from bacteria and fungi to protozoans (mostly single-celled animal-like organisms), have a surprisingly rich story to tell. Here are five fascinating facts about the critters that call your body home.

Your body has more microbes than human cells
The human body is teeming with microbes. A number that gets bandied about is that there are 10 times as many bacterial cells as human cells inside you. While no one's bothered to count them, "the exact number doesn't matter as much as the idea that there are certainly more bacterial cells in our body than human cells," Blaser told LiveScience. As humans have evolved, these microbes have evolved with them. A whole lot of viruses call humans home, too.

And 2013 marks the end of the Human Microbiome Project, a five-year effort involving hundreds of scientists to catalogue the microbiome of human beings. [Image Gallery: Belly Button Bacteria]

You are born bacteria-free
With all these bacteria living inside, it seems natural that humans would just be born with them. Not so. According to Blaser, people are born without bacteria, and acquire them in the first few years of life. Babies get their first dose of microbes as they're passing through their mother's birth canal. (Of course, babies born by Caesarean section don't acquire their microbes this way. In fact, studies show that C-section babies have a markedly different microbiota from vaginal birth babies, and may be at higher risk for certain types of allergies and obesity.)

A baby acquires most of its microbiome by the age of 3, Blaser said — during a time when the baby's metabolic, immune, cognitive and reproductive systems are undergoing extensive development.

Bacteria can be good and bad for you
You're probably aware that while some germs can make you sick, others are important for keeping you healthy and fending off infections. Sometimes, the same bacteria can do both.

Consider Helicobacter pylori, the bacteria responsible for causing stomach ulcers. The bacteria were once found in the majority of the population, but their prevalence has steadily been decreasing, and today only about half of the world's population has it. Most of them do not have symptoms, but a small number develop painful ulcers in an acidic part of the digestive tract (a finding that earned a Nobel Prize in Medicine in 2005).

Helicobacter infections are treatable with antibiotics, but there's a twist: Blaser and colleagues have found the absence of Helicobacterappears to be associated with diseases of the esophagus, such as reflux esophagitis and certain cancers of the esophagus. In other words, Helicobactermay be bad for our stomachs, but good for our throats. Though not all scientists agree, "There's a big body of evidence that Helicobacter has both biological costs and biological benefits," Blaser told LiveScience. [Tiny & Nasty: Images of Things That Make Us Sick]

Antibiotics can cause asthma and obesity
Penicillin was a major breakthrough when Alexander Fleming discovered it in 1928. Antibiotics have enjoyed widespread popularity ever since, but antibiotics overusehas given rise to deadly strains of antibiotic-resistant bacteria, such as Methicillin-resistant Staphylococcus aureus (MRSA).

Now, there's some evidence that antibiotics also increase the risk for developing asthma, inflammatory bowel disease and obesity.

Of course, there are times when antibiotics are necessary. "I would never withhold antibiotics from a very sick child," Blaser told LiveScience. Nevertheless, he said, many common childhood ailments, from ear infections or throat infections, go away by themselves.

(Store-bought) probiotics are overrated
The recognition that bacteria can be good for you has spawned something of a craze in probiotic supplements, consisting of live microbes purported to bestow health benefits. Many people take them after a course of antibiotics. But do they actually work?

"The concept of a probiotic to help re-establish our baseline microbiota after an antibiotic is a good concept," Blaser told LiveScience. "But the idea that, of all thousand species in our bodies, taking a single species that comes from cow or cheese is naïve." Current probiotics are very well marketed, Blaser said, but there's not much benefit. He does think medicine will one day develop probiotics that will be used to treat illness, but as of now, "it's a very young field," he said.

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WISSARD Project

Lake Whillans lies beneath a 66-foot (20-meter) wide ice stream that moves about a meter per day, as opposed to something like a meter per year for the surrounding icecap. Little is known about the possible relation between ice streams on the surface and subglacial river systems, which have only been discovered – and charted through radar – over the past couple of decades.

By Becky Oskin
LiveScience

Blobs and smears of microbial life growing in clear plastic disks are confirmation of a community living in a lake buried beneath the Antarctic ice, scientists studying the lake have said.

Water retrieved from subglacial Lake Whillans contains about 1,000 bacteria per milliliter (about a fifth of a teaspoon) of lake water, biologist John Priscu of Montana State University told Nature News. Petri dishes swiped with samples of the lake water are already growing colonies of microbes at a good rate, Nature News reported.

Lake Whillans is 2,625 feet (800 meters) below the West Antarctic Ice Sheet. After breaking through the ice on Jan. 28, researchers are returning to the United States with 8 gallons (30 liters) of lake water and eight sediment cores from the lake bottom. These samples will be tested for signs of microbial life, which could shed light on the types of extreme life that is able to thrive in such harsh environments.

Reach Becky Oskin at boskin@techmedianetwork.com. Follow her on Twitter @beckyoskin. Follow OurAmazingPlanet on Twitter @OAPlanet. We're also on Facebook and Google+.

• Antarctic Album: Drilling Into Subglacial Lake Whillans
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Christina Bienhold et al.

Colonization of deep-sea wood by various organisms.

By Douglas Main
Our Amazing Planet

Scattered throughout the world's oceans are "wooden cities of life," providing oases for drifting microbes and small animals, a new study has found.  

These sunken chunks of wood, along with other organic material such as dead whales, may act as stepping stones for a variety of bizarre creatures that also thrive near hydrothermal vents, where super-heated water spews out of the seafloor, said Christina Bienhold, a researcher at Germany's Max Planck Institute for Marine Microbiology.

In a recent study, Bienhold's team placed logs on the bottom of the eastern Mediterranean Sea and found that a wide variety of life sprung up there in the span of only a year, including newfound species of aquatic worms, she told OurAmazingPlanet.

spacer

The results of the study, published earlier this month in the online journal PLoS ONE, were especially surprising given that this area is one of the most food-deprived spots in the world's oceans. It thus wouldn't necessarily be expected to harbor a great diversity of life, Bienhold said.

"Nevertheless, a variety of organisms managed to localize, settle, grow and reproduce on our experimental wood deployments," she said.

One of the newly discovered creatures, found by a collaborating scientist, is a species of bloodworm, which feeds on small invertebrates. Another researcher analyzed a different type of marine worm found near the wood, concluding it represented a new species and genus (the taxonomic classification above species). This creature is related to the fireworm, known for its nasty sting.

The most important animals found on the logs were wood-boring mollusks, which showed up in large numbers and began to drill holes and break down the wood, Bienhold said. Her team found that by digesting the wood, these animals produced nutrients that fed a whole different group of organisms, including microbes that typically live near hydrothermal vents, she said. [ Images: Hydrothermal Vents in Action ]

Hydrothermal vents and cold seeps, where methane and other gases bleed out of the ocean floor, were discovered about 30 years ago, along with a host of bizarre creatures that live in these extreme environments, Bienhold said. Since then, scientists have puzzled over how these animals evolved and travel between these isolated oases.  Scientists had asked, "How can these organisms, which depend on specific energy sources for their symbiotic bacteria, disperse across the vast energy-deprived ocean?" she said.

Craig Smith, a researcher with the University of Hawaii at Manoa, who wasn't involved in this study, has found that dead whale carcasses are used by these so-called "chemoautotrophic" organisms, which survive by breaking down chemicals like sulfide and methane. This study, he said, also suggests that wood falls can harbor some of these same creatures.

While the wood in the study was placed there by scientists, wood naturally finds its way into the ocean as dead trees fall into rivers and are swept out to sea, when storm debris is taken by surging waters and even from shipwrecks.

Reach Douglas Main at dmain@techmedianetwork.com. Follow him on Twitter @Douglas_Main. Follow OurAmazingPlanet on Twitter @OAPlanet. We're also on Facebook and Google+.

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