ABOVE: Nematode in biofilm that lives 1.4 km below ground

Organisms of Earth’s deep underground constitute between 15 billion and 23 billion tons of carbon and occupy an estimated volume almost twice that of the oceans combined, scientists from the Deep Carbon Observatory reported yesterday (December 10) in advance of the annual meeting of the American Geophysical Union in Washington, DC.

The scientific team, which includes hundreds of researchers from all over the world, drilled boreholes kilometers below the continents and seafloor to sample microbes. The information collected by the scientists has allowed them to build models of the deep ecosystem and make the estimates of the deep life biomass.

The researchers found a stunning array of life, mostly microbial, and estimate that approximately 70 percent of the total number of Earth’s bacteria and archaea organisms live in this realm. These microbes live at extremes of pressure,...

See “Life Thrives Within the Earth’s Crust

“Exploring the deep subsurface is akin to exploring the Amazon rainforest. There is life everywhere, and everywhere there’s an awe-inspiring abundance of unexpected and unusual organisms,” says Mitch Sogin, a scientist at the Marine Biological Laboratory and co-chair of the Deep Carbon Observatory’s Deep Life team, in a statement.

Many questions remain as to how life spreads under the surface, which energy sources are the most important to sustain these organisms, and whether this is where life began on planet Earth. 

The findings also suggest that extraterrestrial life may be similarly hidden underground. 

“I think it’s probably reasonable to assume that the subsurface of other planets and their moons are habitable, especially since we’ve seen here on Earth that organisms can function far away from sunlight using the energy provided directly from the rocks deep underground,” Rick Colwell, a member of the Deep Carbon Observatory team from Oregon State University, tells BBC News.

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