How Many Species Exist On Earth?

We asked several scientists from various fields what they thought were the greatest mysteries today, and then we added a few that were on our minds, too. This article is one of 15 in LiveScience’s “Greatest Mysteries” series running each weekday.

The prospect of discovering little green men on other planets has long captured our imaginations, but many scientists are just as excited about finding new life forms in our own backyard.Though humans have shared the planet with millions of other creatures for thousands of years, we know surprisingly little about our neighbors—we don’t even know exactly how many flora and fauna call Earth home.

The National Science Foundation’s “Tree of Life” project estimates that there could be anywhere from 5 million to 100 million species on the planet, but science has only identified about 2 million.“We’ve only touched the surface of understanding animal life,” said entomologist Brian Fisher of the California Academy of Sciences. “We’ve discovered just 10 percent of all living things on this planet.”
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