HOW MANY SPECIES ARE ON EARTH?
by eric barron
1. that is a new, estimated total number of species on Earth—the most precise calculation ever offered—with 6.5 million species found on land and 2.2 million dwelling in the ocean depths.
2. The new study, published yesterday in the open access journal PLoS Biology, says a staggering 86% of all species on land and 91% of those in the seas have yet to be discovered, described and catalogued.
3. “This work deduces the most basic number needed to describe our living biosphere,” says co-author Boris Worm of Dalhousie University. “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.”
4. Carl Zimmer explains the method in his Discover blog, The Loom: The method is based on Linnean taxonomy. While we have lots of new species left to find, we may have found most of the classes, orders, and phyla. It turns out that for a number of groups–mammals, birds, and so on–the numbers of each of these rankings rise as you descend the hierarchy.
