One million down - now there's only 750,000 to go

Six years into the Species 2000 programme, researchers say they now have 1,009,000 living organisms contained within their databases.

They hope to complete the basic listing by 2011, reaching an expected total of 1.75 million species, although experts within the programme believe that the actual number of different living organisms is between eight and 12 million.

Professor Thomas Orrell, a biologist at the Smithsonian's National Museum of Natural History in Washington DC, said the finished catalogue would list all known living organisms, from plants and animals to fungi and micro-organisms such as bacteria, protozoa and viruses.

"Many are surprised that, despite over two centuries of work by biologists and the current worldwide interest in biodiversity, there is currently no comprehensive catalogue of all known species of organisms on Earth," Prof Orrell said.

The listing does not include fossil species from the past. It does include elephants, elephant seals, elephant grass and elephant trunk fish, as well as a shark and a virus both with the word elephant in their names.

The Integrated Taxonomic Information System - Species 2000 Catalogue of Life is essentially an umbrella programme, providing access to data maintained by a variety of scientific organisations, each specialising in a certain area.

For example, information on dipteran flies is maintained by the US agriculture department's systematic entomology laboratory at the Smithsonian.

Natural history museums in London, the Netherlands and New York maintain data on the clothes moth, the dragonfly and the spider.

Experts in Canada and Paris keep data on Ichneumon wasps and longhorn beetles.

These lists are peer-reviewed and checked technically, before being integrated into special software for the catalogue. They can be accessed via either the Latin name of the species or its common epithet.

The project, involving some 3,000 biologists, is led by Prof Orrell and Prof Frank Bisby, of the University of Reading.

According to Prof Bisby, several thousand new species are discovered every year.

It is estimated that, on average, 100 new types of fish, 2,000 new flowering plants and thousands of new insects are identified annually.

But new species of mammals are rarer, although in the past few years the world's smallest deer and a new elephant have been discovered, along with three new categories of whale and two lemur sub-species.

Prof Bisby recently spoke of how important the cataloguing work was. "To understand how fast we are losing species from our planet, we need to know how many there are in the first place, and no-one has ever done that," he said.

"Our enterprise is to create a single catalogue of all species of plants, animals, fungi, algae and microbes on Earth.

"The Catalogue of Life is like a telephone book listing all organisms and where they can be found. It is the whole-Earth equivalent of the human genome project."

• THE science of taxonomy - the cataloguing of species - is almost 250 years old. It was pioneered by Carl Linnaeus, a Swedish naturalist, who developed the modern system of naming living creatures.

His prime contribution was to establish conventions for the naming of living organisms that became universally accepted in the scientific world. He classified plants and animals with two-part names, termed binomial nomenclature, which gives both the genus and a "specific descriptor" - for example, Canis Lupus, for wolf.

He also developed a system of scientific classification, in which nature is split into hierarchies, which is still widely used in biological sciences.

But due to the massive scale of the task, until now no unified, official list of all living organisms has existed.

This makes the work of biologists, ecologists and conservationists - who rely on species' names to know just what it is they are studying and conserving - more difficult than it need be.

It is only through the advent of the internet that such a colossal task has been possible.