Species hide thousands of years deep in the Earth's heart

Under hard rock a few kilometers deep of the Earth's crust, in the absence of oxygen, high temperatures and high pressures seem to be unable to survive, living organisms that thrive.

According to the BBC, living organisms found in South African gold mines are considered to be the deepest survival in the Earth's crust , because no ever multicellular organisms have been discovered at a depth of several kilometers below the surface. land.

Scientists are not sure how these organisms descend, but analyzing carbon isotopes indicates they have existed for thousands of years. The ability to survive eternity in such harsh conditions shows that life deep inside the Earth is more complex than any prediction ever.

The discovery of diverse life deep below the Earth's surface since the early 80's caused little surprise for scientists who still believed that in the Earth's heart there existed single-celled organisms such as bacteria. Because of living in high temperature conditions, oxygen levels are very low, extreme pressure and very little food are also extremely tough challenges for any kind of life.

Belgian scientist Gaetan Borgonie argues that if there is a multicellular organism deep beneath the Earth's crust, it could only be a nematode or nematode. Because nematodes are able to live in extremely arduous conditions, they can withstand drought, extreme heat and extremely low temperatures. Moreover, these creatures also know how to apply a cleverly clever strategy to survive: switching to a special form called the enduring stage, the larvae at this stage of metabolism are limited, Develop slowly in inhibitory state to be able to survive a long time in harsh conditions.

The roundworm was discovered in the Kopanang mine.(Photo: Gaetan Borgonie).

The strange little creatures, while in the end of the stamina period, can survive despite being boiled, frozen, crushed, even blown out into space. When the shuttle Columbia collapsed during landing after entering the Earth atmosphere in 2003, the nematode was one of many experimental organisms present on the shuttle, and only the nematode survived. explosion and fall back to Earth.

Nematode worms enter the stamina stage when they suffer from lack of food, high environmental temperature or over-crowded concentration. When the nutrient source is abundant, the nematode will immediately return to its normal state, restoring all the same activities.

Nematode worms appear anywhere on Earth, in hot springs, in the desert, in the high mountains or at the end of the ocean, even in Antarctica. Nematode worms were found to live in the abdomen of animals, including humans, and even in the placenta of sperm whales.

Thus, the harsh place deep underground must have the presence of this austere creature. In order to confirm this argument, Gaetan Borgonie collaborated with Tullis Onstott of Princeton University in New Jersey, to self-finance South Africa, diving into mines deep below the ground for more than three kilometers where researchers had can access the secret world hidden in the ground.

When filtering water samples from exploratory boreholes into the rock floor of the mine, Borgonie discovered many small worms, the first living things discovered at this depth (previously, round worms are known to live only about 10 meters deep.

Moreover, this new roundworm lives in the hard rock layers of the mine, not accidentally brought down when clinging to miners' boots or other sources of infection.

Borgonie spent a year examining each water sample used in the mine without finding any nematodes. This proves that they are not ground-based nematodes that penetrate below the mine. The soil samples around the exploration boreholes are well studied, but the results show that the earthworms belong to another industry. Food sources are bacteria that breed in mines and also attract newer nematodes than those that live on the ground. The evidence suggests that the new nematode has lived for a long time under this depth.

"There are many people who think that we are almost confused to search for multicellular organisms in the depths of the earth, with extremely high compression pressure, high temperature, oxygen and scarce nutrient resources , " Borgonie once said.

Gaetan Borgonie and Tullis Onstott published their findings in 2011, with four new species discovered, living in three separate mines and at different depths.

The two species are Plectus aquatilis and an unprecedented nematode worm found in Driefontein mine at a depth of 0.9 km and a temperature of about 24 degrees C.

Halicephalobus mephisto or demonic worms were discovered in the water of the ore recovered from the fracture streak in Beatrix's gold mine in South Africa, located 240km southwest of Johannesburg, at a depth of 1.3km below the surface of the Earth. At such a depth, the ambient temperature reaches 37 degrees Celsius, higher than anywhere on the ground with roundworms.

Onstott said: "It scared me when I first saw them move" and explained "they look like little black swirls".

Halicephalobus mephisto tolerates high temperatures, they reproduce asexually, and eat bacteria living underground. According to the carbon isotope analysis method, these worms live in underground water from 3,000-12,000 years ago. These worms can also survive in water with very low oxygen levels, below 1%. It is named after Mephistopheles, which means "someone who does not love light" , alluding to the fact that it is found very deep beneath the surface of the Earth.

But the deepest creature in the Earth has never been known, with DNA found in water at a depth of 3.6 km inside the TauTona mine, where temperatures reach 48 degrees Celsius.

According to Borgonie, the fact has shown that the new nematode is not simply extending its existence to the limit of extinction, but rather that it is thriving.

In terms of nutrition, the new roundworm eats the viscous layers of adhesion that are called biofilms , consisting of millions of bacteria clustered together. The bacteria itself is 10 billion times smaller than the worm. Sticky sticky biofilms are closely related to man-made bores. This shows that, by drilling gold-seeking rocks, people unknowingly create the perfect habitat for worms.

Low oxygen levels cannot cause much trouble for nematodes. While humans need their air that contains 21% oxygen, the nematode can live well with only about 0.5%.

High temperatures are not a problem, although the 48 degree Celsius temperature in the TauTona field is considered quite high, there are a number of other nematode species found in hot springs with wool temperatures. to 61 degrees C.

It seems that the worms have evolved to withstand high temperatures and high pressures, long before moving into the mine.

Halicephalobus mephisto or Devil Worms were discovered at a depth of 1.3km below the surface of the Earth.(Photo: Gaetan Borgonie).

Genetic tests show that Halicephalobus mephisto is most closely related to Halicephalobus gingivalis - a free-living nematode, eating bacteria and occasionally living parasites on horses, donkeys, zebras and even humans.

The popular P. aquatilis also has similar toughness, does not require additional adjustment to adapt to low oxygen conditions and high temperatures.

"Although deep underground conditions are extremely harsh for most living organisms, they have not saturated compared to the ability of the roundworm , " Borgonie said.

The nematode worm that lives in the soil can even undergo a cycle "burned by the Sun to dry and then submerged in water or frozen frozen" within 24 hours. Experiencing the extreme states every day continuously throughout the year, plus the tireless effort to find enough food in extremely harsh conditions, it is not worthwhile to have the nematode survive in deep ground. surprise.

But it has not been possible to determine the original location of the newly discovered nematode and the time they came to live underground. The method of carbon isotope analysis shows that these worms live in groundwater from 3,000-12,000 years ago. It can only be guessed that they have lived underground for at least 3,000 years but there is no way to prove it. Most likely they are washed down through cracks in the Earth's crust after rain, and for some reason cannot return to the ground.

"Essentially, the life of the nematode that lives underground is much more pleasant than the life of the round earthworm , " Borgonie said, "underground is really a stable environment compared to the changing environment. every hour on the ground ".

This implies that it is possible to find living organisms in even greater depths. The biggest challenge faced in this depth is high temperature. Although unicellular organisms can survive in extremely high temperature environments, Borgonie thinks it is difficult to find a new nematode that lives in a temperature of more than 60 degrees Celsius.

Although certain limitations exist, deep underground life is always present and there is growing evidence of underground organisms being published.

A 2008 study showed that microorganisms thrive at a depth of 1.6 km under the seabed, with an ambient temperature of 60 to 110 ° C.

In 2013, a small snail with a translucent crust was found nearly a kilometer underground, in a Croatian cave system, including some of the world's deepest caves. The penetrating crust shows that it has grown to adapt to life in caves.

In October 2014, researchers from Yale University reported evidence of bacteria living 19 km deep underground. They examined the types of fossils on Lopez Island off the coast of Washington, USA. These samples contain abnormally high levels of a mild form of carbon, a sign of the bacteria that produce methane. The study also showed that bacteria, buried deep in the Earth's crust, changed the chemical structure of ancient rock masses.

Borgonie also constantly sought life in deeper locations. In August 2015, he found 20 individual nematodes living inside stalactites hanging from the ceiling of the mine. These are round worms that were first discovered living in such a unique environment.

One of the worms found, Monhystrella parvella - is often found on the sea - but is present on a stalactite at a depth of 1.4 km underground in the heart of Beatrix gold mine .

Obviously there are no cracks in the stalactites, so the worms are obviously trapped inside stalactites since they were first formed. Bacteria were also found inside stalactites, indicating that the nematode had a rich source of food available.

M. parvella was also found in the same exploration hole inside the TauTona mine at a depth of 3.6km, and is sharing the title of the deepest creature species in the Earth with a new species never known. . The mystery here is where the nematode originally lived and how they got down to this depth. Originally a marine species, M. parvella needs to live in a saltwater environment, but the location of the TauTona mine in central South Africa, hundreds of kilometers from the sea.

Monhystrella parvella - the nematode species known as the deepest living creature in the Earth's heart.(Photo: Gaetan Borgonie) .

The most plausible explanation is that these nematodes were brought down to the rock floor in the mine from about 250 to 350 million years ago, when the land was originally the background of a closed sea. Moreover, South Africa has a lot of salt fields, which is the place to stop for large migratory birds. These birds may also be the carriers of nematode worms from coastal areas to ground areas above the mines. But Borgonie himself thinks that this is unlikely because round worms can die if isolated from salt water.

Life in deep positions is becoming more and more diverse than what people have ever speculated. In an article published recently in Nature Communications, Borgonie and colleagues reported a series of new discoveries from Driefontein and another mine in South Africa, Kopanang.

The sampling bore they test contains not only bacteria and nematodes, but also a home to a variety of other small animals, from flatworms, segmented worms to fungal species, micro-rotifers (or Crustaceans). car) and even what appears to be a crustacean.

The lifestyle of these creatures is also extremely diverse. Some fungi seem to be easily infected with nematode worms, indicating they are parasites. Moreover, one of the nematodes found to be carnivores, the Brachyurus Mylonchulus is much larger than other organisms and lives by eating smaller species.

These ecosystems appear to be similar in all mines, although the depth of sampling or life expectancy of water sources varies. Obviously they belong to a group of organisms that can live well under great depths, and their representative variants today evolved to adapt well to life deep in the earth.

The discovery of deep underground life has profoundly changed the long-standing rule of places where organisms can survive on our planet.

If the nematode can live deep in the Earth's heart, even if it can survive in an extremely harsh environment, it can be said that there are many other unicellular animals that live underground.

The above findings may inspire others to find a more complex life in harsh places, instead of just looking for bacteria. It is almost certain that many more living organisms will appear in the next few years.

This is also a premise for scientists to find life in planets other than Earth. Microorganisms are the easiest to find and can be found in deep underground.