how many species of animals on earth
The Best Estimate. Mathematician, computer science expert and animal rights advocate Brian Tomasik has attempted to catalog estimates of the number of individual animals in a variety of groupings. According to his data, the total number of individual animals on the earth adds up to approximately 20,000,121,091,000,000,000. This can be written as 20 quintillion, or 20 billion billion. Nature: Number of species on Earth tagged at 8.7 million.