Discovery of all species on Earth achievable this century

'This is excellent news'

October 2011: There are far fewer species on Earth - just two million - than widely believed and it is possible to discover them all this century, according to Associate Professor Mark Costello from The University of Auckland's Leigh Marine Laboratory.

SECRET OF THE SEAS: But the latest theory is that  our oceans contain fewer undiscovered species that had previously been estimated. Photo credit Paul Goldstein

In a keynote address at the World Conference on Marine Biodiversity in Aberdeen recently, Dr Costello presented new research showing that greater progress has been made describing the world's biodiversity than previously thought.

‘This is excellent news,' he said. ‘The discovery and description of new species is essential if we are to protect them, and learning more about the diversity of life on Earth will help us to understand the ecosystems we depend on for our survival. It is a massive task, however, and should be a top priority in world science.

‘People often despair that it will be impossible to discover and describe all of the species on Earth before they go extinct. But this is based on a significant overestimation of both the number of species, the current rate of taxonomic effort in discovering new species, and the rate of extinction.'

Significantly fewer marine species than previously thought
There has been speculation about the number of species for hundreds of years, and estimates have varied by tens of millions. Recently, for instance, it was widely reported that there are more than 8 million species on Earth. Dr Costello and colleagues from Trinity College, Dublin, concluded that there are likely to be just 1.8 to 2 million species.

Their work was based on rates of description of marine, terrestrial and freshwater species recorded in the World Register of Marine Species and Catalogue of Life databases. The authors concluded that around 16 per cent or 0.3 million of the world's species are marine - significantly fewer than previously thought. They predicted that 24 to 31 per cent more marine species, and 21 to 29 per cent more terrestrial species, remain to be discovered.

‘People may not be aware that 18,000 species are being described each year, including 2,000 marine species. With only a modest increase in the rate of discovery, one million new species can be discovered and described in the next 50 years,' says Dr Costello.

He said that as fewer species remain to be discovered they will be harder to find, and that greater coordination of international efforts and free access to online databases was required to ensure that all species are discovered this century.