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Can we name all of Earth's species?

Caption: Striped sea slug in the Philippines.
Credit: [Image courtesy of M. J. Costello]

It's easy to feel overwhelmed by news about how so many of Earth's species are facing extinction. Some experts have even despaired that we won't be able to identify all of the different species of plants, animals and fungi before they disappear forever.

Mark Costello of the University of Auckland in News Zealand disagrees with this gloomy view, however. In an article in the 25 January issue of the journal Science, he and his colleagues argue that researchers could name all of these species in the next 50 years.

Giving names to all these creatures is an important first step to understanding our planet. In fact, some of the first words people probably used were names of plants and animals that were important to them, according to Dr. Costello. Identifying all of the world's species is also important for conserving biodiversity. We have to know what's out there if we want to protect it.

Costello and his colleagues estimate that the number of species on Earth today is 2-8 million (whereas some estimates place this number as high as 100 million) and that 1.5 million are already named.

They also challenge the popular assumption that the number of researchers who discover new species, called "taxonomists," is declining. While this may be true in some regions, the number of taxonomists based in South America and Asia is rising. Amateur taxonomists, who just do this for fun, are also naming many new species.

Some researchers have proposed that global extinction rates are as high as 5 percent per decade, but Costello's team thinks a rate of less than 1 percent per decade is more likely, the authors say. They propose that with an extra US$0.5 to $1 billion per year, taxonomists could name all species within the next five decades.