There are 8.7 million different species on Earth, researchers said on Tuesday, revealing new research that is being billed as the most precise calculation ever offered.

The results are presented in the journal PLoS Biology.

It was previously estimated the number of species existing on Earth was between three million and 100 million, and there are about 1.2 million officially registered.

The 8.7 million figure is a projection based on a mathematical analysis of currently known species. Approximately 86 percent of land species and 91 percent of creatures in the ocean have yet to be discovered, according to the findings by scientists at Dalhousie University in Canada and the University of Hawaii.

The question of how many species exist has intrigued scientists for centuries and the answer, coupled with research by others into species' distribution and abundance, is particularly important now because a host of human activities and influences are accelerating the rate of extinctions, said lead author Camilo Mora of the University of Hawaii.

He was speaking to the Agence France-Presse.

Many species may vanish before we even know of their existence, of their unique niche and function in ecosystems, and of their potential contribution to improved human well-being, he added.

Census Results for the Five Kingdoms of Eukaryotes. These numbers are approximate:

- Animals: 7.77 million species (of which 953,434 have been described and cataloged)

- Plants: 298,000 species (of which 215,644 have been described and cataloged)

- Fungi: 611,000 species (of which 43,271 have been described and cataloged)

- Protozoa: 36,400 species (single-cell organisms with animal-like behavior, such as movement, of which 8,118 have been described and cataloged)

- Chromists: 27,500 species (including, brown algae, diatoms, water molds, of which 13,033 have been described and cataloged)