How many species are there on Earth and in the Ocean

In a new paper, these authors use a new technique to estimate how many eukaryotic species there are.  This is both controversial and important because, frankly, we have little idea of the Earth's biodiversity.  If they're right, we have a lot of exploring to do. Skeptics say they're undercounting with their estimate and we probably have even more exploring to do!  Regardless, we should care because our current human-caused extinction spasm is eliminating species faster than they can be inventoried.  And this is important for pragmatic reasons:  the set of unique adaptations that are found in nature have untapped potentials to help us develop new crops that will withstand climate change, develop new antibiotics and new sources of power and food.  Maintaining biodiversity is an important first step towards helping manage a world with 7-9 million people.  Read the full paper by following the link below; I've appended their popular summary. 

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

Camilo Mora^1,2*, Derek P. Tittensor^1,3,4, Sina Adl¹, Alastair G. B. Simpson¹, Boris Worm¹

1 Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada,2 Department of Geography, University of Hawaii, Honolulu, Hawaii, United States of America, 3 United Nations Environment Programme World Conservation Monitoring Centre, Cambridge, United Kingdom, 4 Microsoft Research, Cambridge, United Kingdom

Knowing the number of species on Earth is one of the most basic yet elusive questions in science. Unfortunately, obtaining an accurate number is constrained by the fact that most species remain to be described and because indirect attempts to answer this question have been highly controversial. Here, we document that the taxonomic classification of species into higher taxonomic groups (from genera to phyla) follows a consistent pattern from which the total number of species in any taxonomic group can be predicted. Assessment of this pattern for all kingdoms of life on Earth predicts ~8.7 million (±1.3 million SE) species globally, of which ~2.2 million (±0.18 million SE) are marine. Our results suggest that some 86% of the species on Earth, and 91% in the ocean, still await description. Closing this knowledge gap will require a renewed interest in exploration and taxonomy, and a continuing effort to catalogue existing biodiversity data in publicly available databases.