How many animal species are there in the world?

Scientists do not know the exact number of living species that exist in the world. In fact, after several centuries of documenting living things, scientists have only managed to document 14% of living species. The remaining 86% of species that are estimated to exist have yet to be discovered.

It is estimated that planet Earth has approximately 8.7 million species. As the rate of extinction has increased, thousands of living species are going extinct without being documented, and their existence will never be known to humans. This is just one of the reasons why it is difficult to estimate the exact number of species that inhabit the Earth.

How Many Species Exist on Earth?

To date, researchers have been able to document around 1.2 million species in existence. However, the total number of species that are in existence is estimated to be somewhere around 8.7 million. Unfortunately, due to extinction, we may never be able to document every species.

In order to categorize species, experts classify species into broad a classification known as a genus, which are then classified into a smaller group called a family. The classification continues until the living organism can no longer be grouped further. Every classification of living organisms belongs to one Kingdom, of which there are five in total. These Kingdoms are known as Animals, Plants, Fungi, Protista, and Monera.

The Extinction Problem

While discovering new species is the easier part of documenting living things, categorizing them is the hard part. Researchers must match the specimens to available samples, analyze their anatomy and DNA, and find their classification lineage. The process is time consuming and at times turns up as inconclusive. The greatest challenge facing species classification is extinction. Extinction takes away key components of the classification chain, which means that scientists routinely can end up with unrelated species.

As of March 2018, the IUCN Red List of Threatened Species listed thousands of species as threatened or vulnerable, which means that the further ability to classify species may be in jeopardy. This means that we may never have an exact species count.