26 August 2011
A team of scientists has adopted a new approach to estimating the total number of living species on Earth, and has come up with 8.7 million. Their findings appear in the online journal, Public Library of Science Biology.
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It's generally accepted that very many species have yet to be discovered, but until now nobody has devised a reliable way to find out just how many. Suggestions for total numbers have ranged from 3 million to a hundred million, but most of these have been no more than intelligent guesses.
Scientists from the Census of Marine Life devised a counting method by identifying numerical patterns linking data on known species. They reckon that there should be about 8.7 million types of living organisms, three-quarters of them animals and the rest plants.
However, since the introduction of the current classification system by Carl Linnaeus in 1758, only a million and a quarter have been catalogued.
The scientists warn that human activity is hastening extinctions, and they note a touch wistfully, that many of the hitherto unknown species may vanish before we even know of their existence.
Paddy Clark, BBC News
Click to hear the vocabulary:
came up with a plan
- intelligent guesses
estimates based on a rational process of thought
- classification system
grouping of organisms following pre-established patterns
identified and recorded
- hastening extinctions
speeding up the disappearance of some species
up to now