Lists of organisms by population

Population densities often reach greater than 1, individuals per liter.

As a result, the true number of species could be much higher or lower than 8. Retrieved 28 November I haven't counted terrestrial individuals, assuming they contribute less to the totals than marine individuals.

Extinctions are a natural part of evolutionary processes, but through most of the history of life on Earth, biological diversity has been increasing. I think the Williams estimate is still pretty reasonable, and it agrees with what we might calculate based on other sources.

86 Percent of Earth's Species Still Unknown?

The new study "takes a hugely clever approach, and I think it's going to turn out to be a pretty important study," said Lucas Joppa , a conservation ecologist at Microsoft Research, the research branch of the software giant. Have you read? Deposit Photos. The study, which is published in the journal PLoS Biology , underlines just how little humans know about what is out there — and which plants and animals will become extinct before scientists can even record their existence.

The Reagan and Waide table in the "Reptiles" section above shows a total amphibian density, adding up each species, of 2. You can see that rodent biomass comprises a much bigger share of the total than in Smil 's Table 2. This jibes with intuitive estimates: Thus a single species of hermit crab is classified in the decapod order, which belongs to the sub-phylum of crustaceans, the phylum of arthropods, and finally the animal kingdom.

March Some scientists say they form the largest animal biomass on earth. Read more. If such a density held uniformly up to some depth d meters in the ocean all over the planet's Explore context. Many sources online report the number of insects as 10 18 or 10 19 , without providing the details underlying this calculation.

The authors, in their analysis of existing data on 1. Eggleston; Ian Hewson The New York Times. The study looked only at forms of life accorded, or potentially accorded, the status of "species" by scientists.

Let us therefore take 10 18 as a working hypothesis.

Planet Earth is home to million species, scientists estimate Environment The Guardian

The authors note that identifying and describing new life forms is expensive and slow, especially when set against the magnitude of species yet to be found or catalogued. Examining 5 m x 5 m quadrats, the researchers found an average of 0. The different methods yield surprisingly consistent estimates of a global bird population of between billion and billion individuals" p. The Brady table here shows densities for "Other fauna" i. Millions of organisms unnamed as extinction accelerates, study says.

This suggests 10 17 to 10 19 non-nematode and non-earthworm invertebrates on land, which is the same as the range suggested in the penultimate sentence of my above quote from Williams Matt Davis, a paleontologist at Aarhus University who led the study, cited the shrew as an example.