How Many Species Are There on Earth and in the Ocean?

By Camilo Mora, Derek P. Tittensor, S. Adl, A. Simpson, Boris Worm. PLoS Biology, 2011

2,652 citations recorded by the source corpus.

The diversity of life is one of the most striking aspects of our planet; hence knowing how many species inhabit Earth is among the most fundamental questions in science. Yet the answer to this question remains enigmatic, as efforts to sample the world's biodiversity to date have been limited and thus have precluded direct quantification of global species richness, and because indirect estimates rely on assumptions that have proven highly controversial. Here we show that the higher taxonomic classification of species (i.e., the assignment of species to phylum, class, order, family, and genus) follows a consistent and predictable pattern from which the total number of species in a taxonomic group can be estimated. This 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. Renewed interest in further exploration and taxonomy is required if this significant gap in our knowledge of life on Earth is to be closed.

Subfields: Ecology, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/485ab05a5a4b16fa7df22554f9066beb3716ff4b

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Citations in the corpus

A global biogeographic classification of the mesopelagic zone (2017, background): “Rigorous quantitative analyses of taxonomic and environmental data for the deep-pelagic zone on a global scale are currently impeded by the spatially patchy and inconsistent manner of data collection over large areas, and because less than 1% of this enormous habitat has been sampled (Webb et al., 2”
Geographical, temporal and taxonomic biases in insect GBIF data on biodiversity and extinction (2021, methodology): “On the other hand, the IUCN’s greatest interest in Odonata and Lepidoptera reinforces what is stated by Sigwart et al. (2019) and Mora et al. (2011) that larger, more brightly colored and conspicuous species are better-studied than their less conspicuous counterparts.”
HOW MANY SPECIES OF ALGAE ARE THERE? (2012, methodology): “Mora et al. (2011), using predictions based on asymptotic parametric regression models and multimodel averaging on the assignment of existing species to phyla, classes, orders and families, came up with a figure of 8.7 million species (±1.3 million SE, giving a range of 7.4–10 million), of which…”
The iNaturalist Challenge 2017 Dataset (2017, background): “Through close inspection, we can see that the ladybug on the left has two spots while the one on the right has seven . been formally described [25].”
Mapping the biosphere: exploring species to understand the origin, organization and sustainability of biodiversity (2012, background): “7 million, suggesting that 87% remain undiscovered and undescribed ( Mora et al , 2011 ).”
Changing trends and persisting biases in three decades of conservation science (2017, result): “In order to provide context for the interpretation of our results, we contrasted the focus of current conservation literature with the following baselines: number of described species (Chapman, 2009;Mora et al., 2011), number of threatened species (IUCN, 2015), and protected area coverage for region”
Projecting the continental accumulation of alien species through to 2050 (2020, positive): “Similar approaches have been applied to estimate the total number of species on Earth from time series of species descriptions (Mora, Tittensor, Adl, Simpson, & Worm, 2011).”