The earth is full of life, but the results of a new study suggest that the bulk of this life does not live where one would think. As part of a large-scale project that lasted a whole decade, scientists conducted a census of the largest and at the same time least studied ecosystem on the planet - the "deep biosphere", which extends several kilometers into the earth's crust. Among the finds, as it turned out, there are very strange organisms that can survive at record depths, pressure and temperature, and even real "zombie bacteria" that have been living on the planet for several million years.
The researchers presented their findings at a meeting of the American Geological Union in Washington, as well as in various scientific journals, including Geobiology and Nature Geoscience.
To implement the project, the Deep Carbon Observatory was created almost ten years ago, which now includes four dozen countries and almost a thousand scientists. Its participants collected and studied hundreds of samples from the deepest layers of the crust and bottom of the sea, which helped them draw up the first map, as well as estimate the total mass, volume and other important properties of the “deep biosphere”.
The study has pushed the boundaries of life significantly, scientists say. It turned out that the total volume of this part of the biosphere is two billion cubic kilometers, which is approximately twice the size of the World Ocean, and its weight exceeds 23 billion tons. This figure is 385 times the mass of all people and 12 times more than all marine and land animals on Earth.
As for the varieties of living organisms found, the researchers talk about the presence of all the main domains of the grouping of organisms in the life system. At the same time, bacteria and archaea, which are part of these domains, dominate the deep biosphere over all others. Moreover, the volumes of their content below the surface can be up to 70 percent of the total mass of these domains on the planet. However, most of the species that are representatives of these domains are still completely unknown to science.
The researchers also note that extremophile organisms are quite common in the bowels of the planet, capable of living under very harsh conditions of temperature and pressure. Moreover, the maximum depth at which such organisms were found under the planet's crust was up to 5 kilometers and up to 10.5 kilometers under the ocean surface.
Perhaps the most unusual of all the findings of scientists are underground multicellular "zombie organisms". One of the most unusual features of these organisms is the extremely slow metabolic rate associated with a constant lack of oxygen or nutrients. For this reason, researchers compare such inhabitants of the underworld with “zombies” from fantasy literature, who also did not differ in their high speed of “thinking” and actions. Thanks to this feature, scientists say, such organisms can exist for several million years.
Promotional video:
The participants in the project for the study of the "underworld" note that they only slightly "looked" under the surface and many questions still remain unsolved for them. How could life have penetrated so deep? Why are many communities of underground microbes from different parts of the Earth almost indistinguishable from each other and has this life existed in the lithosphere since the formation of the planet?
Geologists and biologists hope that further excavations will help answer these questions, as well as find out what role these microbes and multicellular creatures play in the carbon cycle in nature, and how they can affect global warming and other climate fluctuations.
Nikolay Khizhnyak