Study Says There May Be a Trillion Species on Earth

Scientists have discovered approximately 1 trillion species with only one-thousandths of 1 percent now identified, according to biologists. The estimation was made based on the intersection of large datasets and universal scaling laws.

Experts agree that there are more species on Earth than people have actually discovered. However, the number has always been unsure. The Washington Post reported that previous studies have estimated it somewhere between 3 million to 100 million. A paper from 2011 estimated it around 8.7 million species of eukaryotes which include plants, animals, fungi, and some single-celled organisms on the planet. However, these studies have also said that about 86% of these organisms have yet to be discovered.

Scientists from Indiana University headed by Jay T. Lennon, associate professor in the IU Bloomington College of Arts and Sciences' Department of Biology and Kenneth J. Locey, a postdoctoral fellow in the department combined microbial, plant and animal datasets from different sources (government, academic, and citizen science) which resulted in the largest compilation of its kind. These data represent more than 5.6 million microscopic and nonmicroscopic species from 35,000 locations across the world's oceans and continents, not including Antarctica.

"Estimating the number of species on Earth is among the great challenges in biology," Lennon said. "Our study combines the largest available datasets with ecological models and new ecological rules for how biodiversity relates to abundance. This gave us a new and rigorous estimate for the number of microbial species on Earth.

According to Science Daily, Lennon also explained that until recently, they didn't have enough tools to truly estimate the number of microbial species in the natural environment. He added saying that as the total number of organism in a given community increase, the number of species also grew and the ways the different species changed in number were similar among all communities.

This made researchers conclude that they have somehow discovered what appeared to be a universal scaling law. By combining their scaling law with a well-established biodiversity model, they were able to come up with an estimate of the number of microbial species that should exist. By doing that, they were able to conclude that Earth likely contains upwards of a trillion species of microbes alone.

However, they found that fewer than 10 million microbe species have been observed in nature, meaning that there may be 100,000 times more microbial species on the planet than what have been discovered so far. Being able to find all of those would be a marvelous task. The researchers also noted that they need a major increase in microbial sampling efforts around the world.

"The profound magnitude of our prediction for Earth's microbial diversity stresses the need for continued investigation," they wrote. "We expect the dominance scaling law that we uncovered to be valuable in predicting richness, commonness, and rarity across all scales of abundance. To move forward, biologists will need to push beyond current computational limits and increase their investment in collaborative sampling efforts to catalog Earth's microbial diversity."