Pelagibacter (IMAGE) University of Washington Caption Pelagibacter, or SAR11, is a single-celled bacterium that survives off dissolved carbon throughout the oceans. It makes up one in four cells on the ocean's surface. Credit NOAA Usage Restrictions With credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.