How many species are there on Earth and in the ocean?
2011
Estimating the Number of Species on Earth
publication
Evidence: moderate
Author Information
Author(s): Robert M. May
Primary Institution: Zoology Department, Oxford University
Hypothesis
How many species are alive on earth today, and how many can we lose while still maintaining ecosystem services?
Conclusion
Mora et al. estimate there are approximately 8.7 million eukaryotic species on Earth, with most being terrestrial.
Supporting Evidence
- We know the number of books in the US Library of Congress but not how many species exist on Earth.
- Taxonomic effort is unevenly distributed among vertebrates, plants, and invertebrates.
- Mora et al. suggest a global total of 8.7 million eukaryotic species.
- Field taxonomists are discovering about 15,000 new species each year.
- Accelerating extinction rates complicate the task of cataloguing species.
Takeaway
Scientists think there are about 8.7 million different kinds of living things on Earth, and we need to know this to help take care of our planet.
Methodology
Mora et al. used taxonomic categories and patterns to estimate the total number of distinct eukaryotic species.
Limitations
The estimate does not account for accelerating extinction rates.
Statistical Information
Confidence Interval
±1.3 million
Digital Object Identifier (DOI)
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