How many species on Earth? Now we have the answer!

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Scientists have come up with what they hope is a definitive answer to the question: How many species are there on Earth? And the answer? 8.7 million - give or take 1.3 million!

The new estimate is thought to be the most precise yet and finds that there are 6.5 million on land and the last 25% made up of the 2.2 million species living in the oceans. The study also found that a massive 91% of all marine species are yet to be discovered.

The figure was released by census of Marine Life Scientists after they used an innovative, new technique based on numerical relationships between higher taxonomic groups and species to narrow the margin of error in estimates from what was previously anything from between 3 million and 100 million species.

Only around 250,000 marine species have currently been described and catalogued so the new estimate is an increase of 1.2 million marine species from the number given by the Census when it was released last year.

Lead author Camilo Mora of the University of Hawaii and Dalhousie University in Halifax, Canada said: "The question of how many species exist has intrigued scientists for centuries and the answer, coupled with research by others into species' distribution and abundance, is particularly important now because a host of human activities and influences are accelerating the rate of extinctions. Many species may vanish before we even know of their existence, of their unique niche and function in ecosystems, and of their potential contribution to improved human well-being."

Co-author Boris Worm of Dalhousie University added: "This work deduces the most basic number needed to describe our living biosphere. 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. Humanity has committed itself to saving species from extinction, but until now we have had little real idea of even how many there are."
 
Dr Worm added that the existing IUCN Red List only currently monitors less than 1% of the world species. With Mora concluding: "With the clock of extinction now ticking faster for many species, I believe speeding the inventory of Earth's species merits high scientific and societal priority. Renewed interest in further exploration and taxonomy could allow us to fully answer this most basic question: What lives on Earth?"

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