A United Nations meeting of the Convention on Biological Diversity in Brazil from March 20-31 will review calls to extend protected areas into the high seas to help safeguard marine life ranging from seaweeds to sharks and from starfish to corals.

Scientists say the issue is pressing because life is being found in parts of the ocean long thought barren -- in the sediments of abyssal plains on the ocean floor, around subsea mountains, deep sea corals or hydrothermal vents.

"Great attention gets paid to rainforests because of the diversity of life there," said US oceanographer Sylvia Earle, an executive director of Conservation International. "Diversity in the oceans is even greater."

"We should have at least as much of the oceans protected as of the land," she said. Most existing protected sea areas are close to coasts, such as around Australia's Great Barrier reef, Ecuador's Galapagos Islands or in the Mediterranean.

"We need better international cooperation and marine protected areas are one way forward," said Kristina Maria Gjerde, an expert at the Geneva-based World Conservation Union which groups governments and environmental groups.

CATCHING SQUIRRELS WITH A BULLDOZER

"Key areas for protection are deep sea coral reefs and seamounts which are being strip-mined by bottom trawl fishing," said Simon Cripps, director of the Global Marine Programme at the WWF environmental group.

Fishing fleets are trawling ever deeper international waters in search of new commercial species, like the orange roughy, as traditional stocks, such as cod or tuna, dwindle due to over-exploitation.

Unregulated fishing is by far the biggest threat to marine biodiversity because trawlers dragging nets over deep corals, for instance, may be destroying nurseries for fish.

Earle said deep-sea trawling was like trying to catch squirrels in a forest with a bulldozer.

New technologies are also opening up the ocean depths: Exxon Mobil Corp. says it can drill for oil in waters approaching 3,000 metres (9,840 ft) deep. Deep water sponges have uses in fiber optics and heat-loving bacteria from thermal vents have promise in helping produce ethanol fuel.

Yet much of the ocean remains as mysterious as Mars.

"We still can't begin to say what's down there," said Ron O'Dor, chief scientist of the Census of Marine Life, a 10-year $1 billion international effort to map life in the seas.

"We've only explored an area the size of 10 football fields of the abyssal plains," he said, referring to the flat sediments on the seabed covering 60 percent of the planet's surface at an average depth of 4 km (2.5 miles).

One recent expedition off Angola turned up more than 400 new species in abyssal sediments, mostly tiny single-cell organisms.

And only 250 of about 15,000 seamounts, rising from the plains but not tall enough to become islands, have been sampled.

Scientists went to the Arctic last year to explore two seamounts marked on charts. "We discovered they weren't even there," O'Dor said. "How much do we know about seamounts? Obviously not enough."

And scientists were stunned in 1977 by the discovery of deep sea hydrothermal vents, leaking acidic water heated by subsea magma and sustaining heat-loving bacteria, tube worms and crabs. Many more such vents have been found since.

Many experts say implementation of existing laws, drafted before the deep-sea marine finds of recent decades, is insufficient to protect the high seas -- the area beyond the 200 nautical mile territorial waters.

HIGH SEAS