Total Number of Species on Earth
Only around 275,000 marine species have been identified, compared to some 1.5 million terrestrial species. In reality, coral reef ecosystems alone are probably home to at least one million species, and as many as 10 million more may lurk in the deep ocean basins (only one-tenth of which have been systematically mapped). It is reasonably certain, then, that the greater part of species diversity remains to be discovered. Estimates of the total number of species on earth range from as 'few' as 3.6 million to as many as 100 million.
10,000 new species are being discovered every year!