SMALL IS HUGE. “Almost all of the life in the oceans, by weight, is prokaryotic (bacteria and archaea), with viruses and protists making up roughly equal amounts of the remaining. The big stuff, the whales and other charismatic mega-fauna are actually pretty trivial in terms of overall biomass. 95% to 98% of the living material, by weight, in the oceans is microscopic. In a litre of coastal seawater there are more viruses than there are people on the planet.”
http://www.nrcresearchpress.com/doi/full/10.1139/gen-2013-0152