These numbers were calculated by a new, cross-validated
analytical method, based upon mathematical models and the rate of species discovery, making this estimate the most accurate ever, the scientists claimed, and significantly narrowing previous vaguer estimates that ranged between 3 to 100 million species, mostly based upon expert opinions and educated guesses, ScienceDaily reported
According to the research findings, published in PLoS Biology
with an editorial
by the famed Oxford zoologist Robert M. May
advocating boosting efforts to search for undiscovered animals because of the potential benefits to be gained in many fields, an astounding 86% of land species and 91% of ocean dwellers have yet to be discovered and documented.
About 7.8 million animal species far outnumber 611,000 species of fungi, 298,000 of plants, 36,400 of protozoa
and 27,500 of chromista
, the study estimated. But only 953,434 species of animals, 43,271 of fungi, 215,644 of plants, 8,118 of protozoans, and 13,033 of chromista have been described and classified by the (continuously updated and modified) biological taxonomic system
originated by Carl Linnaeus in 1758
The study counted only lifeforms in the eukaryotic
domain of the three-domain phylogenetic
tree of life, those with cells containing complex membrane-enclosed structures, and excluded vast numbers of prokaryotic
-celled micro-organisms (bacteria and archaea
) and viruses.
Finding and describing all undiscovered species with traditional methods would take hundreds of researchers well over a thousand years and cost billions of dollars, by today's standards and prices, but new technologies, such as DNA barcoding
, will speed up the process and reduce the costs considerably, the researchers maintained.
Lead author Camilo Mora of Dalhousie University in Halifax, Canada, and the University of Hawaii remarked in a written statement
, "With the clock of extinction now ticking faster for many species, I believe speeding the inventory of Earth's species merits high scientific and societal priority. Renewed interest in further exploration and taxonomy could allow us to fully answer this most basic question: What lives on Earth?"
Interviewed by TIME Science
about this study, Pulitzer Prize-winning Harvard biologist Edward O. Wilson
, who did not participate in the project, contended searching for undiscovered species before they become extinct is well worth the effort, for their potential medical, scientific and hunger-relieving benefits.