"The abyss is not the dark hole anymore," he said.

The researchers discovered 5,600 new marine species on top of the 230,000 animals already known to live in the world's oceans and they hope to add several thousand more when the final census is released in London on October 4, 2010.

Scientists predict that there could be more than one million species which remain undiscovered.

Search continues

Odd Aksel Bergstad, an oceanographer based at the University of Bergin in Norway, told Al Jazeera: "There is a huge number left to discover especially in the vast muddy areas of the deep sea floor."

marine census

  Click here to visit the Census of Marine Life website

"The reality is that the deep sea is a frontier that hasn't been studied very much, but with modern technology and still after 10 years we've only scratched the surface of this huge environment," he said.

Among the creatures identified in the deep sea areas were luminous jellyfish and gelatinous creatures known as finned octopods, or "dumbos," because they flap earlike fins and look like the cartoon elephant.

"Most of the organisms in the deep sea depend on the steady rain and transport of material from the sunlit upper layers and this comes in many forms from small organic particles and dead animals," Bergstad said.

"But one of the main problems for all these deep sea creatures is the scarcity of food, the darkness and the huge volumes they have to cope with. However, these animals are uniquely adapted."

Oil-eating worm

Experts also found a tubeworm at a depth of 990m on the seafloor in one part of the Gulf of Mexico.

After using a robotic arm to lift the tubeworm from a hole on the seabed, oil gushed out and they discovered it was consuming chemicals from the decomposing oil.

Carney said that oil companies focused mostly on geological surveys to find deposits but that the presence of tubewarms could also be a marker.

"You certainly have a source or methane or liquid petroleum nearby if you find these tubeworms," he said.

Another trip to the seafloor of Antarctica recorded the Osedax, a whalebone-eating worm.

Although the ocean depths are permanently black, many animals create their own light with luminous markings to help spot or attract prey or a mate. Scientists also said many have working eyes.

A few creatures that normally live in the sunlit zone visit the abyss, such as the southern elephant seal which was registered at a depth of 2,388m.