When answering the question of “how many species exist?”, there is no easy way of doing it. Although there is no certain answer, scientists can estimate that there is likely somewhere between 5 million to 100 million different species. It’s such a difficult question to answer because you have to realize that smallest of life forms are included. Insects, bacteria and all microbes need to be accounted for.
As of August 2007, about 2 million species had been identified. Scientists continue to discover new species all the time. A ten year study in the Eastern Himalayas led scientists to find over 350 new species. Read more about these discoveries on Science Daily.
Another puzzle for scientists to figure out is how many species of plants and animals have gone extinct on Earth since life began. This question, of course being a much harder one to answer, is virtually impossible.
To stay up to date on the latest findings, Science Daily features a section of their website devoted to news of recent specie discoveries.