The earth is full of life, but a new study suggests that the bulk of this life inhabits is not where you would think. In a large-scale project, which lasted a decade, scientists conduct a census of the largest and at the same time less explored ecosystems on the planet – the “deep biosphere,” which extends for several kilometres into the earth’s crust. Among the findings, as it turned out, there are very strange organisms that can survive at record-breaking depths, pressure and temperature, and even real “zombie bacteria” living on the planet for several million years.
Their findings the researchers presented at the meeting of the American geological Union, Washington DC, and in various scientific journals, including Nature Geoscience and Geobiology.
For the project nearly a decade ago, the organization was created Deep Carbon Observatory, which now includes four dozen countries and almost a thousand scientists. The participants collected and examined hundreds of samples from the deep layers of the cortex and the bottom of the sea, which helped them create the first map and also to assess the total mass, volume, and other important properties of the “deep biosphere”.
This study has expanded the boundaries of life, scientists say. It turned out that the total volume of this part of the biosphere is two billion cubic kilometers, about twice the size of the Global ocean, and its weight exceeds 23 billion tons. This number is 385 times the mass of all people and 12 times more than any sea and land animal on Earth.
“Ten years ago, we never thought that our feet may be hiding as much diversity of life. We believed that it can exist only in a small handful of selected corners of the Earth. Now we know that it is found virtually everywhere. We can say that we have only begun to explore this “dark matter” of the biosphere, its deep part,” says Isabelle Daniel of the University of Lyon (France).
As for the species discovered living organisms, the researchers say the presence of all key domains of groups of organisms in the system of life. While bacteria and archaea, which are part of these domains that dominate in the deep biosphere over all others. Moreover, the volume of content under the surface can be up to 70 percent of the total weight of these domains on the planet. The majority of species that are representatives of these domains remain completely unknown to science.
The researchers also noted that in the bowels of the planet are quite common organisms-extremophiles, able to live under very severe conditions of temperature and pressure. The maximum depth at which met such organisms under the crust of the planet was up to 5 miles and up to 10.5 kilometers beneath the ocean surface.
Perhaps the most unusual of all the findings of scientists are underground multicellular “organisms-zombies.” One of the most unusual features of these organisms is an extremely slow metabolic rate associated with a constant lack of oxygen or nutrients. For this reason, researchers compare such of the inhabitants of the underground world with “zombies” from fantasy literature, too, not possessed of great speed “thinking” and actions. Thanks to this feature, the researchers say, these organisms can exist for several million years.
The participants of the research project “the lower world” note that they are only slightly “looked” under the surface and many questions still remain unsolved. How life could penetrate to such a depth? Why is a underground community of microbes from different parts of the Earth are almost indistinguishable from each other and there was this life in the lithosphere from the time of planet formation?
Geologists and biologists hope that further excavation will help to answer these questions, and find out what role these microbes and multicellular creatures play in the carbon cycle in nature and how they may be affecting global warming and other climate variations.
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