Most Earth species still unknown: Brazil expert

SAO PAULO (AFP) - The vast majority of the Earth's estimated 13 million species are still unknown and to describe them all would take up to 2,000 years, according to a leading Brazilian scientist.

"We estimate that there are a total of around 13 million species (known and unknown) in the world," Dr Thomas Lewinsohn, a renowned professor of ecology at the State University of Campinas (UNICAMP) in Sao Paulo state.

"Out of these, roughly 1.75 million species, including micro-organisms, plants, insects, bacteria and animals, have been described," he told AFP in an interview.

And there is actually no consensus on the exact number of species, with experts relying on extrapolation based on known data.