Earth species

There are approximately 8.7 million different types of plant and animal on Earth but 90 per cent of them have yet to be discovered, according to new estimates.

Previous guesses had put the total number of different species at anywhere between three million and 100 million, but a new calculation based on the way in which life forms are classified puts the estimate at the lower end of that scale.

The list of known species currently stands at about 1.2 million, but experts said that advances in technology meant that the remainder could be found and classified within the next century.

The study was undertaken by researchers from the Census of Marine Life, a ten-year project involving 2,700 scientists from more than 80 countries aimed at assessing the diversity of life in our seas and oceans which concluded in October 2010.

Since the 18th century species have been officially classified under a pyramidlike system, with each placed in a series of related groups.

For example humans are categorised in the same order as chimpanzees, the same class as dogs and cats and the same overall kingdom as all other animals.

By analysing the rate at which the more generic groups, such as mammals and fish, break down into smaller ones scientists were able to predict the number of species at the lowest level despite not having found them yet.

When tested against well-known groups like mammals, birds and fish, the method accurately predicted the number of individual species, study leader Dr Camilo Mora said.

The formula predicted there are 7.77 million species of animal, of which fewer than one million have been catalogued, 298,000 species of plants, and 611,000 species of fungi on the planet.

read more: telegraph