Scientists from around the globe are taking stock of the world's oceans. The Census of Marine Life is a 10-year, $1 billion effort to identify and catalog the underwater world. The Census - which began in 2000 - marks its midway point with colorful discoveries worldwide.

The on-line inventory now has 8.4 million records covering 40,000 marine species of the 200,000 described in scientific literature so far. Ron O'Dor, senior scientist for the Census of Marine Life, expects those numbers to climb. "We estimate that by the time the Census is completed by 2010 we will have collected at least a million new species," he says.

While the database includes everything from microscopic plankton to large whales, 90% of the samples come from the first 100 meters of the ocean's depth. The rest, says David Welch, who heads a field-tracking program in North America, is largely unknown. "The average depth of the ocean is 4,000 meters, though less than one-tenth of one percent (of species) come from 3,000 meters or less," he says. "Most of the depth of the ocean hasn't been sampled. And, the deep ocean is actually the largest ecological zone in the world and probably has the biggest biomass as well."

Census discoveries in 2005 included a bright pink octopus in the Arctic, tiny carnivorous sponges in the Southern Ocean, and the first known hydrothermal vents south of the equator in the Atlantic.

The Census also reported 78 new species of fish and a biologically dead zone at the epicenter of the 2004 Indonesian tsunami.

Technology has accelerated the pace of discovery. Researchers working on the continental shelf from Washington State to Alaska have surgically implanted 2,700 fish with almond-size tags. Project leader David Welch says electronic devices on the ocean floor scan each fish as it passes by. "We can reconstruct which fish went where and therefore which fish stock -- which are populations of a particular type of fish -- went in direction A, (which in) direction B, and how many fish survived to reach each of these lines."

The data reveals the movement and survival of each tagged fish as it migrates within the ecosystem -- important details for fisheries management and protection of endangered species.

The current array stretches across more than 1,550 kilometers in North America and includes 135 listening stations. The team expects to have 2,000 in place by 2010. David Welch says the goal is to replicate the network across continental shelves worldwide. "We actually had expression of interest from all seven continents including Antarctica in starting to put in these systems," he says.

Satellites follow another 2,000 animals including species of shark, birds, turtles, seals and sea lions electronically tagged in 2005. And, adapted from the human genome project is a tool used to catalog new ocean species. Senior scientist Ron O'Dor says DNA barcodes can rapidly and accurately identify species. "It doesn't give these species a name," he says, "but at least it gives an identifier that we can use for the record, and people in the future can deal with the descriptions." He says a lot of the process can be automated. "If we get a new specimen from, for example, deep sea vents that no one has ever seen before," he says, "we can take a small piece of that and get a sequence for it. That sequence can be written out on a chart, and that becomes the reference number or barcode for that specimen."

The Census already has barcodes for 800 fish species with another 1,000 to be added by mid-2006. That library could rapidly expand as single cell and microbial species, which make up 90% of the biomass of the ocean, are barcoded. Evidence of that were the 400 new species of microscopic worms and crustaceans that live between the grains of sediment at the bottom of the sea discovered at a single site off the coast of Africa in 2005.

Ron O'Dor says expanding our knowledge of the ocean frontier has been an international effort with more than 1,700 experts from 73 countries involved in the project.