Living according to the devil

An amazing discovery forces scientists to reexamine the question of whether life can exist even in the most extreme conditions on Earth and in space

Douglas Fox

In January 2015, glacier researchers drilled a shaft in the ice, to a depth of 740 meters, in the meeting area between the Antarctic continent and the sea. A robot launched into the depths of the shaft discovered fish and other animals that exist in water that is only 10 meters deep, at a distance of 850 kilometers from the open sea and sunlight.

According to the accepted theory, this remote place was expected to be almost lifeless. But the fish there feed on tiny crustaceans, which in turn feed on bacteria. The bacteria in this isolated place can find their food in organic residues that fall from the bottom of the ice sheet that slides into the water. In the absence of sunlight and without photosynthesis, the bacteria extract energy from these residues in unconventional ways.

The discovery raises the possibility that life can exist on Earth in places previously considered uninhabitable, and even on planets and moons such as the moon Europa orbiting Jupiter.

Marine life was the last thing that Robert Zook and about a dozen scientists expected to find in January 2015 when they set out to study the glaciers in the confluence between the continent and the sea, where the ice sheet breaks off from the ground, slips into the water and forms the "Ross Ice Shelf". They came all the way to this remote location to try to understand how the lower ice layer, the "soft underbelly" of the West Antarctic Ice Sheet, which is slowly drifting towards the sea, is responding to climate change. They included in the expedition several biologists who specialized in the study of primitive bacteria, but not a single scientist who studies larger creatures.

On January 16, the group huddled around the video monitors in a dark room set up on top of the ice sheet, like a makeshift control center built inside a metal container. For days, tractors dragged the box, which was narrowly adapted to its purpose, mounted on four giant skis, along with half a million kilograms of equipment and supplies, to this point located 850 kilometers from the front of the ice shelf facing the open sea. Here, using hot water, the crew drilled a hole as wide as a basketball hoop, to a depth of 740 meters, to the tiny wedge of water trapped between the seabed below, near the coastline, and the glacier above it. To investigate what was going on in the depths of the pit, they hung a robot they called Deep SCINI on a cable and carefully lowered it through the borehole. A scrolling strap maintains an electronic connection between the robot and the control room.

Deep SCINI. is a remotely operated robot (ROV), which must withstand the freezing cold and high pressure prevailing in the depths. But Zook had to build and design it in a race against time, and only had time to test it in a swimming pool. Now, in the field, the group of scientists followed with bated breath for 40 minutes the narrow robot, two meters long, dangling down, deeper and deeper down the pit. Every curve along the white ice walls of the shaft was reflected brightly in the light of the flashlight mounted on the robot's nose, creating the impression of a cosmic wormhole leading to another world.

The scientists watching what was happening in the cramped room breathed a sigh of relief when the walls of the pit suddenly disappeared and were replaced by a dark space. At this point, Deep SCINI has already passed through the bottom of the ice shelf and penetrated the sleeve of salty seawater, which is only 10 meters deep, trapped beneath it. Before their eyes was revealed the desolate, rocky and lifeless seabed, a dark and frozen land that no human eye had ever seen before. The water samples that the team of scientists pumped through the borehole a few days earlier were clear and fresh, without any sign of life. Ross Powell, a glacial geologist at Northern Illinois University and one of the expedition leaders, described this area of ​​the coastline as a "pretty hostile" place when he reported the findings in a satellite phone call after the samples were collected.

Justin Burnett, who was piloting the robot, slid his fingers across the touchpad to guide Deep SCINI upwards, towards the underside of the floating ice shelf. The lights of the remotely operated vehicle revealed a lumpy ice ceiling embedded in alluvial soil. Here and there a tiny grain of dirt broke off from the ceiling, glinting in the light on its way down like a falling star. But every once in a while, this or that shooting star behaved strangely: it seemed to change direction and leap to the side. The scientists watching the spectacle could not be sure of this, but it seemed to them that something was moving on the video monitor.

Brent began pointing Deep SCINI back towards the sea floor when suddenly the image on the monitor froze. The robot turned itself off to avoid overheating, a rather ironic situation in the frozen water it was in, which remained in a liquid state at a temperature of minus 2 degrees Celsius only thanks to the salinity of the water and the tremendous pressure exerted on it by the ice above. Zook radioed the machine operator, who was on duty outside the control room, and asked him to lower the robot to the bottom while the team of scientists restarted it.

When the video cameras started working, one of the crew members in the cold container burst into enthusiastic calls: "Look! Look! Look! I do not believe!" All eyes were directed to the left, towards the camera monitor pointing downwards, to the bottom of the sea. A graceful figure glided across the screen, her shape getting narrower like an exclamation mark, her translucent body bluish, brown, pinkish. It was a fish about the length of a small kitchen knife. Those present in the room were stunned. The expedition that came here to explore glaciers had just discovered a complex life form in one of the most hostile places in the world.

That day, the robot spent six whole hours in the depths, during which it met three different species of fish, 20 or 30 individuals in total. Shrimp-like Shatsadaim (amphipods) flew past him. The team also noticed a chestnut brown jellyfish, and a multicolored jellyfish-like creature swimming above, most likely from the Masercan family. "The impression we got was that it was a whole community living there," Powell told me not long after. "This was not a random event." In the depths that were considered desolate, it turned out, a rich life exists.

The definition of the task has changed in one. The order of the day was to capture as many of these creatures as possible so that scientists could examine and study them. Zook therefore built a makeshift net trap, installed it on Deep SCINI and placed fish meat inside as bait. When the robot was lowered to the bottom of the sea the next time, its camera lens caught dozens of stedts circling the trap like flies around a trash can over the course of four hours. And when the winch operator lifted the robot back to the surface, the trap contained more than 50 tiny crabs. The team froze them and flew them to the McMurdo Research Station, the main US logistics center in Antarctica. Zook and his colleagues prepared to leave the place.

The complex life forms found there in such abundance was a sensational discovery. The findings are still making waves in the scientific community and are undermining assumptions that have been accepted for many years regarding life on our planet and the possibility of finding life on other stars.

The evidence for the existence of life under the ice in Antarctica has accumulated bit by bit. The climate there is unbearably harsh, and exploration trips are expensive, especially those that require drilling hundreds of meters deep into the ice. For these reasons, the little information that scientists were able to gather originated from the front of the ice shelves, in the open sea area.

In the 60s, glaciologists accidentally discovered a colony of seals that miraculously survived despite remaining permanently isolated on the McMurdo Ice Shelf, 20 kilometers from the edge of the shelf, too far to slide back to sea. The seals gathered by a deep crevasse, where the ice shelf had collapsed beneath it. They used to dive into the crack in search of food in the seawater at the bottom. The biologists wondered what food the seals could find in the dark waters where, they believed, there was no life. These seals looked even fatter than their counterparts that lived in the open sea area, so the mystery was doubly great. But scientists had no way to solve it.

A clue to the solution was accidentally found in 1975, when low cloud cover forced John Oliver to land the helicopter he was flying near a nearby crack in the ice. Oliver, who at the time was an oceanographer at the Scripps Institution of Oceanography in La Jolla, California, and his flight mate decided to dive into the crack. They slid down the ice wall, below the surface of the water, and at a depth of 40 meters an alien sight was revealed to their eyes: hundreds of glowing green sea lilies planted in the ice. A year later, the two returned to the site to collect some sea lilies, but discovered that the water was littered with swirling ice crystals and had to abandon the planned dive. They retraced their steps as they had come, without collecting or even photographing the marine creatures. All that remained of their discovery was a single sentence forgotten by heart in a scientific article about glaciers.

In 2003, 3,000 kilometers away, Yuki Watanabe, a biologist at the University of Tokyo, set up camp on the thin surface of seasonal sea ice near the Reiser-Larsen Ice Shelf. These ice patches, which form in winter on the surface of the water in the frontal areas of ice shelves, allowed him to stay in the cabin during the winter and study the feeding habits of seals. Devices attached to these animals showed that they often dive to a depth of 150 meters below the surface of the water. Watanabe therefore assumed that fish congregate in this area. But when he attached a camera to one of the seals, the resulting images showed sea creatures with flapping hunting arms hanging upside down from the bottom of the ice shelf: it was a most surprising discovery. Watanbe therefore hypothesized that seals dive below the edge of the shelf to hunt any prey that hangs from it.

Few were aware of the discoveries that Oliver Watanabe made by accident when Zook was called in 2010 to help a team of engineers investigate robotic hot water drilling. Then the drilling was carried out in the Ross Ice Shelf, at a site called Coulman High, 10 kilometers from the front of the shelf, where the ice thickness reached 250 meters. After the team melted through the ice, Zook sent his robot down the shaft. As he navigated the robot along the bottom of the ice shelf, we discovered a strange sight on the video monitor: thousands of hunting arms of sea anemones, which seemed like ghosts. These creatures usually live on the bottom of the sea, anchored to it. But here the sea lilies were hanging upside down from the bottom of the ice shelf, their stems embedded in the ice. Worms also lived in the ice, in their own burrows. Shrimp-like stingrays and krill crabs were seen passing through the water, and fish swam here and there. One of them swam upside down, with his belly sliding on the ice ceiling. The sight was "absolutely bizarre," Zook said, "it was the last thing we expected to find there."

Merrimagne Dailey, a sea urchin expert at Ohio State University, was stunned when she saw the first photos. "It was amazing. They looked like bats hanging from the ceiling of a cave. It never occurred to me that sea lilies could exist there," Daley said.

No one imagined an ecosystem that exists upside down on the underside of an ice shelf. But scientists could at least provide an explanation for the existence of such a system based on the accepted theory at the time. Complex life forms beneath the ice in the frontal regions of ice shelves can find sustenance in ocean water carried with the current from the nearby sunny open sea, biologists explained. But, according to this explanation, life will slow down rapidly as the distance from the open sea and sunlight increases. Smaller and smaller creatures will eat the leftover food, until there is no food left at all. This line will mark the beginning of a vast area, inhabited only by bacteria, that extends for hundreds of kilometers under the huge ice shelves that are the size of countries, towards the continent, to the area where the ice sheet meets the land.

Sunlight does not reach this isolated area completely buried under the ice, and photosynthesis cannot occur there at all. The most desolate areas of the ocean floor known to us are dark areas in the depths of the sea, in the heart of vast oceans, 6,000 meters below the surface of the water. Life at these depths depends on particles of dead plankton creatures that sink down from the upper layers of water illuminated by sunlight far above. But there is no sea above the meeting area between the ice shelf and the continent. Stacey Kim, a scientist who studies the ecology of the Antarctic sea depths at the Marine Research Laboratories in Moss Landing, California, hypothesized that the area would be many times more isolated from the depths of the sea.

 

The Antarctic Drilling Project, ANDRILL, at the University of Nebraska-Lincoln, which funded the 2010 expedition to Antarctica, hired Zook's services in 2013 to upgrade the robot he built, which later became known as Deep SCINI. Zook designed and built windows made of sapphire for the robot's cameras and a body made of millions of tiny hollow glass balls, so that it would withstand water pressure at depths of up to 1,000 meters and allow the robot to be sent on exploration missions even in more distant parts of the ice shelf, under thicker layers of ice. When the job was completed, Zuk was invited to join, along with Deep SCINI, the research expedition led by Powell for the unprecedented drilling mission in the area where the ice shelf meets the continent.

The 53-year-old Zook is very different from the image of the typical research scientist. He never completed his studies in high school. After spending several years designing early models of wireless telephones, he was hired in 1997 as a maintenance man for radio relay stations and aerial navigation beacons at the McMurdo Research Station. Zook and Brent, a doctoral student in robotics, labored for six months to complete Deep SCINI on time, working 15 hours a day in a stuffy brick hangar in Lincoln, Nebraska. They only received funding to develop a prototype and not a robot for actual research. And so, when the two arrived at the drilling site on January 2, 2015, the robot still lacked a navigation system and a power management system, making it prone to overheating.

After Deep SCINI was raised from the well following the discovery of the fish, the team lowered into the well a set of oceanographic research instruments that Powell had brought with him, and left it on the seabed for 20 hours. The instruments measured the currents in the ocean and the salinity of the water, data that may indicate the rate of melting of the ice. They also monitored the concentrations of oxygen and other chemicals in the water, which after the discovery became extremely important. And all the while, fish and shrimp passed by the camera installed in the kit.

The members of the delegation "wracked their heads" trying to find an explanation for the existence of such animals in the place, and they sat down and discussed the question during the meals they held. "We have to ask ourselves what are they eating," said Brent Christner, a Louisiana State University microbiologist who has spent 15 years studying the microbes in Antarctica. The seabed in this area is too far from the sunlight, and if water from the front of the ice shelf drifts into the area, it is likely that there are no food remnants left in it at the end of the slow, years-long journey from the open sea.

The mystery increased in view of the enormous amounts of energy these animals require compared to bacteria. Fish exist at the top of an ecological food pyramid. At the bottom of the pyramid, bacteria use energy from sunlight or chemicals to extract carbon dioxide molecules dissolved in water and multiply. Scatsidae eat the bacteria and recycle the carbon in their bodies. And the fish, at the top of the pyramid, eat the Shatzades. But moving carbon, or energy, up the food pyramid isn't efficient enough, said John Prisco, a microbial ecologist at Montana State University who co-led this year's research expedition. About 100 kilograms of bacteria are needed to feed one kilogram of fish.

Mystery also surrounds the million square kilometers of land hidden beneath the West Antarctic ice sheet. Glacier researchers drilled shafts in the ice at several points in the area, down to the mud at the bottom. The mud is rich in the microscopic shells of diatoms that lived there from 20 million to five million years ago, evidence of a shallow sea that covered the area in earlier, warmer times. Seismic remote mapping has revealed ancient layers of sediment hundreds of meters thick containing billions of tons of decaying marine organisms that died and sank to the bottom.

The team of scientists who conducted the research drilling in January 2015 in the meeting area of ​​the ice shelf and the continent, in early 2013 drilled through the ice 100 kilometers away, in the interior of the continent, and discovered a subglacial water reservoir called Lake Williams. (I joined them on this journey.) Organic carbon originating from ancient marine layers makes up 0.3% of the mud in the lake, an impressive amount similar to that in the soil that feeds the desert prairies in the USA. The team also discovered bacteria in the lake. In the absence of sunlight and without photosynthesis, the bacteria produce energy using the oxygen in the lake, which they use to "burn" chemicals such as ammonium ions (NH₄⁺) and methane (CH₄) fluttering upwards from the layers of decaying organisms at its bottom.

Is it possible that the fish found in the area where the ice shelf meets the land also feed from a similar source?

When Deep SCINI was lowered down the drill shaft, just before the robot entered the water space below the ice, the glassy ice walls of the shaft became sealed and the whiteness turned brown. The bottom twenty meters of the ice was embedded with the same type of carbon-rich muddy sediment discovered at Williams Lake: frozen material that had stuck to the bottom of the glacier as it slid across the land thousands of years ago.

Bits of this muddy sediment fell from the ice ceiling as Deep SCINI explored the space where the ocean water flowed. It was those tiny grains of dirt that resembled shooting stars. Every day, a layer of ice about one millimeter thick melts at the bottom of the ice sheet, and by the way, the particles rich in nutrients fall out of it. Frisco noticed that the Shatzdai were eagerly drawn to these bits that fell in a cloud from the bottom of the shaft as the robot shook its sides. He wondered if the ice, which blocks the passage of sunlight to the place, serves at the same time as a source of food for the creatures living there, and provides them with organic waste that feeds the bacteria at the bottom of the food pyramid. The fish "get their food from above," Frisco said, "I'm almost XNUMX percent sure of that."

Frisco likens the glaciers sliding from the land to a kind of slow conveyor that transports ice rich in muddy sediments, which melts a little when it comes into contact with sea water and in the process releases the organic waste stored in it into the water. The muddy ice melts at a fairly rapid rate, so that the full load is released along 40 kilometers from the coastline. This muddy sediment shower "could help fertilize seawater and create a habitable zone" at the back of the ice shelf, said Slavok Tulaczyk, a glaciologist at the University of California, Santa Cruz, who led this year's expedition with Powell and Frisco.

Such isolated habitats may be found all along the coastline, hidden under the floating ice shelves, in the land-sea confluence zones that extend for more than 20,000 kilometers around the Antarctic coast. Imagine that you are looking at Antarctica from space, and through the ice you can see a 40 kilometer wide ring of fish and other animals that surrounds the entire coastline: an extensive and thriving ecosystem, not a lifeless undercarriage.

But even in the vast expanses of the dark ocean beneath the ice, between this marine oasis and the open sea, life may be found. In 1977, scientists drilled a single shaft in the Ross Ice Shelf, 475 kilometers from the open sea, and opened a window to a water column 240 meters deep. A camera that was lowered through the hole took several hundred pictures of the seabed, and in two of them fish were seen. Shatsadaim were also seen in them. "People didn't attach much importance to it at the time," says Kim. But now, after fish have been discovered in a much more isolated environment and far from the open sea, it seems that this observation made years ago deserves special attention.

This insight, that there is rich life beneath the ice shelves, has become even more fascinating today. Recent ice-penetrating radar images from aircraft, which enable mapping of the 500D structure of the ice sheet, show water originating from the melting ice, which is lighter than seawater because it contains less salt, flowing in well-defined paths towards the open sea, for many centuries of kilometers under the ice, starting in the area where the ice sheet broke off from the ground. "It's a reverse river," says David Holland, an oceanographer at New York University. These upside-down rivers melt the ice in their path and carve channels in it that can be 3,000 to 200 meters wide, and their penetration depth up to the ice ceiling, up to XNUMX meters. If indeed these rivers carry with them organic debris released as the ice melted, they may feed organisms along these reverse channels.

The sense of wonder at the existence of life in such remote places on Earth even increases when biologists examine the photographs and animal samples provided by Zook. Also impressive are the photographs of sea anemones hanging upside down from the ice ceiling collected in 2010 at Coleman High (the information was only made public in 2013, after a long delay). The amazing finding is that these species of creatures living in such extreme conditions are, amazingly, completely normal creatures. "The habitat is very strange," says Daly, "but there is nothing unusual about the creatures that live there."

The sea anemones, for example, belong to a well-known family of creatures common throughout the world. "Anatomically, there's nothing unexpected about them," says Daly. No special gland or other organ that has not been seen so far that could explain how they burrow into the ice and don't freeze to death. It is possible that they survive using salt that they concentrate around their bodies, which can be used as an antifreeze agent. However, Dailey noticed one sign of evolutionary adaptation: their eggs are particularly fatty, so they float to the ice ceiling above rather than sink to the sea floor.

The red, shrimp-like Shatsads discovered in January 2015 probably belong to a well-known group of creatures that live at the bottom of the world's deepest oceans. "Various scavengers," as Kathleen Conlan, a marine biologist at the Canadian Museum of Nature in Ottawa, calls them. According to her, in Antarctica, "if there is a source of organic matter that is found in the sediments [found in the ice above], and it allows the development of bacteria, then the shatsadas can devour it."

The bluish-brown-pinkish fish caught on camera are also familiar. Arthur DeVries, a fish expert from the University of Illinois at Urbana-Champaign, who has studied the fish in Antarctica for about 50 years, identified them as Antarctic silverfish, one of the most common species in the continent's coastal waters. Ironically, these fish are sensitive to cold and can easily freeze to death.

Discovering such mundane creatures in such strange places hints at a basic truth: the most remote places on Earth that have yet to be explored are not necessarily as hostile as we thought. "We see ourselves as the authority on everything to do with our planet," says Brittany Schmidt, a planetary scientist at the Georgia Institute of Technology. The January discovery "shows us how naive we are," she says. "That's the real lesson, for me."

Indeed, complex forms of life can exist in various and strange places that until now were considered unfit for habitation. We often define a habitable environment in terms of the presence of liquid water, whether on Earth or on other planets or moons. Schmidt sees things in a different light: "I try to find geological sources of energy," in places where there is tectonic activity or where there are sliding glaciers, for example, carbon originating from ancient sedimentary layers may rise again on the surface and serve as a source of food. "These cycles can sustain life," she says.

Additional discoveries from the recent period provide support for this way of thinking. Swarms of worms have been discovered on the sea floor in the Gulf of Mexico, in ice blocks made of methane hydrate, an exotic solid form of natural gas and water formed under high pressure, protruding from the sea floor. Although the living environment of the worms is extremely strange, their menu is typical for these creatures: bacteria, which in turn feed on the methane. Worms of a different kind have been found in the water bubbling through cracks in the rocks, at a depth of three kilometers below the earth's surface, where they feed on bacteria that find their food in the minerals in the rock. Some of the bacteria living in the depths even subsist, in a sense, on nuclear energy, since they consume hydrogen produced in the decay process of uranium and other radioactive elements.

In this context, it is worth noting Lake Vostok, a subglacial lake located in East Antarctica, deep inside the continent, 1,500 kilometers from the drilling site to which the research expedition went in January 2015. The lake is buried under an ice sheet 3,700 meters thick, and has been completely isolated from air and sunlight for 15 million years . In the 90s, Russian scientists drilled through the ice to the front of the lake, without penetrating the lake itself, and pumped ice that had frozen above the surface of the lake's water. Well-known polar biologists reacted with skepticism and even ridicule when, in 2013, Scott Rogers, a biologist at Bowling Green State University in Ohio, published the findings of testing the DNA found trapped in the ice. He discovered DNA traces of marine creatures that apparently live in the lake, including sea lilies and crabs.

"I think we should be open to the idea," Tulachik says of Rogers' findings. Although Lake Vostok is buried very deep in ice, it is quite possible that it contains considerable amounts of oxygen, which enters the lake water as ancient air bubbles are released from the melting ice above.

A similar process may be occurring on the surface of Europa, an ice-covered moon orbiting the planet Jupiter. Scientists believe that beneath Europa's ice sheet, which is 10 to 20 kilometers thick, is hidden an internal ocean of liquid water. Schmidt and others have found evidence of strong currents in Europa's inner ocean, driven by tidal cycles that occur under the influence of Jupiter's gravitational field and generate frictional heat. Assuming the heat is causing the ice sheet to melt, this could allow for an ecosystem similar to that found in Antarctica, subglacial Williams Lake, or under the sea ice shelf. Warm currents can cause a kind of tectonic activity, where ice from Europa's surface will sink and melt in the interior ocean, carrying with it a constant supply of oxygen and other substances.

The discovery of living creatures in the water in the meeting areas between the continent and the ice shelf raises many questions. After Powell maps the ocean currents reaching this area and estimates the rate of warming there, it will be possible to know at what rate the melting ice is expected to release the stored nutrients. A set of instruments that Tulachik lowered into the depths of the borehole before it was sealed with ice will provide more information about ocean currents. The instruments measure the angle of inclination of the ice shelf, which changes with the daily tidal cycles and transmit the data weekly via satellite communication. Frisco and Christner will examine the contents of the guts of the shatzaids they collected and analyze its genetic fingerprint to find out what they feed on. They will also analyze the DNA sequence of the bacteria found in the water and mud to determine what energy sources are driving this food web: ammonium ions, sulfur or other chemicals.

Powell hopes to return to the area with a larger robot that will be able to explore deeper under the ice sheet, record what is happening in the depths on video and measure the concentrations of chemicals in the water. Zook hopes to catch some live fish and other creatures. In any case, he certainly feels lucky given Deep SCINI's performance so far. "The rule of thumb [in Antarctica] is that no big technology project succeeds in its first year," Zook told me as the expedition packed up last January. The success of Deep SCINI "was a small miracle."