As it was estimated by biologists from the US University of Arizona, there are 2 billion living species on Earth, most of them bacteria.

The 'Pie of Life' (or the taxonomic groups that contain the most species) is dominated by bacteria (78 percent), followed by fungi (7.4 percent).

The Pie of Life also includes animals (7.3 percent), protists (7.3 percent) and plants (0.02 percent), said the most recent estimate on biodiversity issued by The Quarterly Review of Biology.

For the researchers, to date about 1.5 million species have been formally described in the scientific literature, most of them insects, while bacteria comprise less than 1 percent of all described species.

The researchers estimated that each insect species is likely to host at least 10 bacterial species found nowhere else, thus, they carried out the new assessment.

They said that rather than being dominated by insects, as traditionally shown, the Pie of Life is dominated by bacteria.