The first draft, with 25 fully completed entries including text, pictures and video, is due to be launched at a conference in Monterey, California, on Wednesday. A further 30,000 have less detailed information.

"Our major message to the world is 'Here's our first attempt at putting together this encyclopedia, please give us our feedback, your criticisms, your comments'," James Edwards, executive director of the project, told Reuters.

Edward Wilson, a Harvard biologist whose call for a portrait of life in a 2003 speech helped spur creation of the encyclopedia, said: "This thing is taking off like a big booster rocket. ... It is already galvanising research."

The encyclopedia has been dubbed a "macroscope" -- helping to identify big patterns often overseen by scientists working in narrow fields.

Researchers into human ageing, for instance, often study a small range of creatures such as fruit flies or worms in laboratories to try to untangle why organisms age.

"We'd like to look across a group of organisms, a family of flies, for example, for the extremes," said Edwards.

Flies with unusually short or long life cycles could be compared to classic laboratory fruit flies for molecular or genetic clues to ageing. Such information across similar species is not now readily available.

LOW-COST, EFFICIENT

Or a developing country facing an outbreak of a new mosquito-borne disease or an invasion of crop-eating beetles could consult the encyclopedia to uncover breeding and feeding habits of the insects to work out ways to stop them.

"I'd hope that within 12 months we'll start to see papers written that could not have been done without the existence of the Encyclopedia of Life," said Jesse Ausubel, chairman of the project at the Rockefeller University in New York City.

He said scientists might, for instance, study hundreds of thousands of species to test Cope's Rule, which states that creatures tend to get bigger over geological time. Horses are an example -- their ancestors were dog-sized.

"The Encyclopedia of Life allows the low-cost efficient assembly of lots of databases that individual researchers would never be able to get together," he told Reuters.

He likened the current lack of an encyclopedia to trying to study a language without a dictionary. "The very fact of assembling all these species is a revolution," he said.

The project is led by the US Field Museum, Harvard University, Marine Biological Laboratory, Missouri Botanical Garden, Smithsonian Institution, and Biodiversity Heritage Library -- a group that includes London's Natural History Museum, the New York Botanical Garden and the Royal Botanic Garden in Kew, England.

-- For Reuters latest environment blogs go to: http://blogs.reuters.com/environment/