By the time they're done in 2010, scientists say they may find more than 2 million different species of marine life.
Three hundred scientists from 53 countries participating in the $1 billion study reported their first findings Thursday, three years into the decade-long project. So far, the Census of Marine Life comprised 15,304 species of fish and 194,696 to 214,696 species of animals and plants, estimated to be roughly 10 percent of the world's total.
The census is adding about 150 to 200 species of fish and 1,700 species of animals and plants each year.
The scientists said they believe the oceans that extend across 70 percent of Earth's surface hold about 20,000 species of fish and up to 1.98 million species of animals and plants. Many of those could be basic and small life forms, such as worms and jellyfish.
"We've tended to be interested in the things that we eat," said Jesse Ausubel, an environmental scientist at The Rockefeller University in New York City. He helps run the census for the Alfred P. Sloan Foundation, which provided $20 million in funding.
"We've tended not to be interested in the things that pass through our nets or don't taste good," Ausubel said. "But the small critters are tremendously important in the ecosystem ... and in an evolutionary sense, the small things came first. They're ancient, and they're survivors."
Scientists hope to gain a better understanding of life in the mostly unexplored seas, learning about evolution and climate, pole to pole. Environmentalists hope to use it to counter over-fishing and pollution that has depleted the ocean's resources. Industry hopes it will lead to more efficient fishing and shipping, new pharmaceuticals and industrial compounds.
"Our goal by 2010 is to know as much about life in the oceans as we know about life on land now," said Ronald O'Dor, a marine biologist at Dalhousie University in Canada and the project's chief scientist.
"No one would claim that we know everything about life on land," he said. "There are probably still a few hundred thousand beetles in tropical forests that haven't been described. But we'd like to aim for parity."
The project grew from scientists' concerns after a 1995 report by the National Academy of Sciences found that human population growth was fast changing the diversity of life in the oceans, possibly irreversibly.
They wanted to learn what still was there.
The census started organization six years ago, partly through the efforts of J. Frederick Grassle, director of Rutgers University's Institute of Marine & Coastal Sciences. Actual work began in 2000. It has cost $70 million so far and the price tag eventually is expected to reach $1 billion, paid by participating governments.
Their work may never really be finished.
"We know we won't have counted every animal," said Grassle, who chairs the census's scientific steering committee. "The limit on the knowable is in major part the resources that can go into the problem."
By John Heilprin