The answer: we have NO IDEA. Most taxonomists think that we have not even begun to discover all the species that live on Earth. After nearly 250 years of organized study and exploration, and the finding of over 15,000 new living beings each year, taxonomists are still uncomfortable giving concrete estimates. And they are the experts! What makes counting species so hard?
Scientists have identified and named nearly 8.7 million species, but that number is constantly challenged by scientists presenting new methods and models for estimating how many more we have to find. Statistical models are the most inexact of sciences. And scientists are proposing new models for estimating the number of species every year, each with wildly different numbers.
But it’s not just statistics. One of the biggest reasons we do not know how many species share our planet is that 99 percent of all potential living space is under the ocean, and we humans have explored less than 10 percent of it.
