May 17, 2014

Number of known species

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’)