bio mass? ie: if you weigh all the individuals of a given species, the cumulative weight of which species would be the highest?how about for a genus or subgenus?from the dictionary definition for species: A fundamental category of taxonomic classification, ranking below a genus or subgenus and consisting of related organisms capable of interbreeding.so i don't think 'microbes' or 'bacteria' will fit the species bill. however, they probably will fit the genus or subgenus classification..i'd also appreciate pointers to sources. thanks.

Hard question. E O Wilson the entomologist says that ants are.But if you were to ask the microbiology entrepreneur Craig Venter he might tell you that microbes (if you include bacteria, bacteriophages, archaea, protists, fungi and whatever else there is among this group) are the most numerous bio mass on earth.I cannot imagine that all the greenery on earth would outweigh the soil and sea bacteria.Can anyone else help?

No one knows.Bacteria and algae by far out-weigh multicellular genera and species. Which one is the weightiest is unknown. For example, every human being has one trillion, give or take a few hundred billion, E. coli living in their gut. E. coli also live in a wide range of animals.