'Planet Earth is home to 8.7 million species, scientists estimate. Latest bid to count and catalogue the living world is billed as the most accurate yet, but only a tiny proportion is known to science.
'"We know we are losing species because of human activity, but we can't really appreciate the magnitude of species lost until we know what species are there," he said.
'An astonishing 86% of all plants and animals on land and 91% of those in the seas have yet to be named and catalogued, the study said.
'"It's not that we just don't know the names in the phone book. We don't know how big the phone book is," said Derek Tittensor, a co-author who works for the UN Environment Programme.'
From http://www.guardian.co.uk/environment/2011/aug/23/species-earth-estimate-scientists accessed 24/08/2011