How many species are there?
The most-cited estimate is 8.7 million eukaryotic species — animals, plants, fungi and protists — give or take 1.3 million, of which about 2.2 million are marine. Only about 2.2 million have actually been described and named, so roughly three-quarters of species on Earth have never been formally recorded. Bacteria and archaea are excluded from that figure entirely because the species concept works differently for them; estimates there run to millions or billions depending on the definition. At current rates of description it would take another thousand years to name the rest.
How the figure is arrived at
The 2011 estimate used the shape of the taxonomic hierarchy rather than sampling. The number of phyla, classes, orders, families and genera in a well-catalogued group follows a predictable curve; fit that curve to the higher, better-known ranks and extrapolate down to species. It is an unusual method because it does not require going anywhere.
How confident it is
- Low estimate
- 7,400,000
- High estimate
- 10,000,000
- Spread
- 1.4× between the bounds
Other living things and the natural world counts
- How many people are there in the world? about 8.2 billion
- How many grains of sand are there on Earth? roughly 7.5 quintillion on the world's beaches
- How many ants are there in the world? about 20 quadrillion
- How many trees are there in the world? about 3 trillion
- How many insects are there? about 10 quintillion
- How many people have ever lived? about 117 billion
- How many drops of water are there in the ocean? about 27 septillion
- How many fish are there in the sea? somewhere between 3 trillion and 100 trillion — nobody knows
- How many species are endangered? more than 45,000 assessed as threatened
- How many bees are there in the world? roughly 2 trillion managed honey bees
- How many birds are there in the world? about 50 billion wild birds
- How many bacteria are there on Earth? about 5 nonillion
- How many earthquakes are there each year? about 20,000 located a year — around 55 a day
- How many chickens are there in the world? about 26 billion alive at any moment
Common questions
- How many species are there?
- about 8.7 million
- How is that estimated?
- The 2011 estimate used the shape of the taxonomic hierarchy rather than sampling. The number of phyla, classes, orders, families and genera in a well-catalogued group follows a predictable curve; fit that curve to the higher, better-known ranks and extrapolate down to species. It is an unusual method because it does not require going anywhere.
Related pages
- How many people are there in the world? about 8.2 billion
- How many grains of sand are there on Earth? roughly 7.5 quintillion on the world's beaches
- How many ants are there in the world? about 20 quadrillion
- How many trees are there in the world? about 3 trillion
- How many insects are there? about 10 quintillion
- How many people have ever lived? about 117 billion
- How many drops of water are there in the ocean? about 27 septillion
- How many fish are there in the sea? somewhere between 3 trillion and 100 trillion — nobody knows
- How many stars are there in the universe? Space and the universe
- How many countries are there in the world? Things people built
- How many bones are in the human body? The human body
- How many stars are there in the Milky Way? Space and the universe
- How many atoms are there in the universe? Space and the universe
- How many galaxies are there? Space and the universe
Sources
- Typical range compiled from manufacturer specifications — At One Place