Once considered a barren plain dotted with hydrothermal vents, the seafloor’s rocky regions appear to be teeming with microbial life, say scientists
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“Initial research predicted that life could in fact exist in such a cold, dark, rocky environment,” said Santelli. “But we really didn’t expect to find it thriving at the levels we observed.” Surprised by this diversity, the scientists tested more than one site and arrived at consistent results, making it likely, according to Santelli and Edwards, that rich microbial life extends across the ocean floor. “This may represent the largest surface area on Earth for microbes to colonize,” said Edwards.
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Santelli and Edwards also found that the higher microbial diversity on ocean-bottom rocks compared favorably with other life-rich places in the oceans, such as hydrothermal vents. These findings raise the question of where these bacteria find their energy, Santelli said.

“We scratched our heads about what was supporting this high level of growth,” Edwards said. With evidence that the oceanic crust supports more bacteria than overlying water, the scientists hypothesized that reactions with the rocks themselves might offer fuel for life.