How Many Species Are There on Earth and in the Ocean? Camilo Mora, Derek P. Tittensor, Sina Adl, Alastair G. B. Simpson, Boris Worm
Published: August 23, 2011
https://doi.org/10.1371/journal.pbio.1001127
From the abstract:
[The] approach was validated against well-known taxa, and when applied to all domains of life, it predicts ∼8.7 million (±1.3 million SE) eukaryotic species globally, of which ∼2.2 million (±0.18 million SE) are marine. In spite of 250 years of taxonomic classification and over 1.2 million species already catalogued in a central database, our results suggest that some 86% of existing species on Earth and 91% of species in the ocean still await description.Thus, between 7.4 and 10 million species! We've catalogued 1.2m. So, we know next to nothing about species!
How many pre-historic species are there? Wikipedia has a few pages of them. Nothing, compared to the current estimate, so it would appear that we know nothing about them as well!
