There are 8.74 million species in the world, give or take 1.3 million, and around 90 per cent of them remain undiscovered, according to the calculations of a group of pioneering scientists. They are the first ones to offer a precise figure for the total number of living species in the ecosystem; for decades this crucial statistic has been considered to lie anywhere between three and 100 million.
“This work deduces the most basic number needed to describe our living biosphere,” says author Boris Worm of Dalhousie University, Canada. “If we did not know — even by an order of magnitude (1 million? 10 million? 100 million?) — the number of people in a nation, how would we plan for the future? It is the same with biodiversity.”
This new study does point to a more workable range by considerably narrowing it. It has also revealed that after 250 years of rigorous taxonomy, only 14 per cent of species on land and nine per cent in the oceans have been recorded.
“The immense effort entering all known species in taxonomic databases makes our analysis possible,” says co-author Derek Tittensor of Microsoft Research and the UN Environment Progra-mme’s World Conservation Monitor-ing Centre. “As these databases grow and improve, our method can be refined and updated to provide an even more precise estimate.”
This prediction was made from statistical analysis based on a simple approach: number of higher taxonomy categories are linked to number of species within them. The scientists spotted this consistent pattern, they call “former predicts the latter”, in the classification and simply extrapolated to get the number of species in each kingdom.