How many species on Earth? 8.7 million give or take

Wed Aug 24, 2011 12:27pm EDT
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By David Fogarty

SINGAPORE (Reuters) - Scientists have yet to discover, or classify, about 90 percent of the plant and animal species on Earth, which is estimated to be home to just under 9 million species, a study says.

The study, published in the open-access journal PLoS Biology on Wednesday, vastly increases the estimated richness of life on the planet. More than 1.2 million species have been formally described and named so far.

Scientists have long tried to classify life on Earth and to finally figure out how many species there are but estimates have varied wildly from 3 million to 100 million.

The quest is no mere scientific fancy. Humans derive huge benefits from the richness of life on the planet, from foods to medicines, to clean air and water. Knowing how many species there are and taking steps to ramp up the search and description could lead to more discoveries that benefit mankind.

The recent surge in extinction rates only made the quest more urgent, the scientists said.

"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," said Camilo Mora of the University of Hawaii and Dalhousie University in Halifax, Canada, who led the study.

Some U.N. studies say the world is facing the worst losses since the dinosaurs vanished 65 million years ago.

Species are classified according to a 250-year-old taxonomy system. This groups life into a pyramid-like hierarchy, with species at the base, then genus, family, order, class, phylum, kingdom and domain.   Continued...

<p>A bug crawls on a leaf at Sundarijal Nagarjun National Park, northeast of Nepal's capital, Kathmandu, July 24, 2011. REUTERS/Navesh Chitrakar</p>