The number of known species - characterized by scientific
analysis and description - is more than 1.7 million, including nearly 1 million
species of insects, about 14,000 species of amphibians and reptiles, and 5,400 mammalian
species. It is estimated that there are also trillions of microscopic organisms
like bacteria. (Adapted from 'The New York Times ‘Smarter by Sunday – 52 Weekends of
Essential Knowledge for the Curious Mind’)