The ubiquitous bug recycles organic matter, providing the nutrients needed by algae to produce about half of the oxygen that enters the Earth's atmosphere everyday. This carbon cycle ultimately affects all plant and animal life on the Earth.
The bug has several unique characteristics, including the smallest known genetic structure of any independent cell.
Through sheer numbers, this microbe has a huge role in consuming organic carbon, which it uses to generate energy while producing carbon dioxide and water in the process, the journal Nature reports.
But it has an enemy in the shape of 'Pelagiphages' viruses now known to infect SAR11 and routinely kill millions of these cells every second.
SAR11 has a huge effect on the amount of carbon dioxide that enters the atmosphere, and the overall biology of the oceans, said Stephen Giovannoni, professor of microbiology at Oregon State University.
"There's a war going on in our oceans, a huge war, and we never even saw it. This is an important piece of the puzzle in how carbon is stored or released in the sea," he said, who led the study.
What the new research shows, is that SAR11 is competitive, good at scavenging organic carbon, and effective at changing to avoid infection, said Giovannoni.
Due to that, it thrives and persists in abundance even though it's constantly being killed by the new viruses that have been discovered, according to an Oregon statement.
The discovery of the Pelagiphage viral families was made by Yanlin Zhao, Michael Schwalbach and Ben Temperton, postdoctoral researchers working with Giovannoni.