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We're Not Alone: 8,699,999 other species on Earth

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


We are just one of a newly estimated 8.7 million eukaryotic species, according to a study published last week in PLoS One. But it doesn’t look like we’ll get to know a lot of them.

We’ve catalogued about 1.2 million species in the last 250 years (24.8 species per taxonomist’s career at a cost of about US$48,500 per species). Assuming the current rate and cost, the authors note that describing Earth’s remaining species may take as long as 1,200 years and would require 303,000 taxonomists at an approximated cost of US$364 billion.

The slow rate in the description of species means that many species could become extinct before we know they even existed. (For an example, see this recent story about a newly discovered Hawaiian bird that could already be extinct.)


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Taxonomic experts had suggested a range of 3 to 100 million species, and these authors narrow it down. Of the 8.7 million species, an estimated 2.2 million are marine species.

This study reminded me of one of my favorite moment’s in a Dean Young poem: You're not alone. Read the full poem here.