SAR stands for Sargasso, the sea to the east of Bermuda, but the S of SAR could just as well stand for “success”. SAR11 is the name of a tiny micro-organism first found in the Sargasso Sea and which now looks likely to be the most abundant life form on the planet (excluding viruses). A report last month from Stephen Giovannoni of the Oregon State University estimates that an astounding 2.4 × 1028 SAR11 cells live in the oceans (Nature, vol 420, p 806).
What do these vast numbers mean? Comparison with the bigger creatures we normally think…
