An international team has been studying samples of plankton collected during a three-year global expedition.
They have so far found 35,000 species of bacteria, 5,000 new viruses and 150,000 single-celled plants and creatures.
They believe that the majority of these are new to science.
Dr Chris Bowler, from the National Centre for Scientific Research (CNRS), in Paris, told BBC News: "We have the most complete description yet of planktonic organisms to date: what's there in terms of viruses, bacteria and protozoa - we finally have a catalogue of what is present globally."
Live Viewers: 36 Total Pageviews: 87