The largest scientific study of its kind estimates that Earth could play host to more than 1 trillion different species, which means we’ve probably only identified a vanishingly small proportion of them – only about one-thousandth of 1 percent.
To figure this out, biologists in the US combined more than 35,000 separate analyses of microscopic and non-microscopic species. This massive compilation of documented life forms covered 5.6 million species sampled from locations across all the world’s oceans and land masses (excluding Antarctica), and if the scientists are correct in their estimates, we’ve got a long way to go before we’ll have seen all that Earth has to offer.
“Estimating the number of species on Earth is among the great challenges in biology,” said one of the team, Jay T. Lennon from Indiana University. “Our study combines the largest available datasets with ecological models and new ecological rules for how biodiversity relates to abundance. This gave us a new and rigorous estimate for the number of microbial species on Earth.” Source: The largest study of life forms ever has estimated that Earth is home to 1 TRILLION species