05 September 2005

New camera identifies unknown sea creatures

After fleeing in the face of Hurricane Katrina, ocean researchers have returned to the Gulf Mexico where they are getting a revealing new look at the deep sea.

"We are exploring the deep sea with new eyes," oceanographer Tamara Frank of the Harbor Branch Oceanographic Institution said on Friday.

Frank and others aboard the National Oceanic and Atmospheric Administration Research Vessel Seward Johnson are using a camera that operates with dim red light to study life on the sea floor.

They have found a variety of deep-dwelling shellfish that produce their own light, animals with surprising ability to see ultraviolet light and a previously unknown type of squid, two-metre-long, that attacked their camera.

"Imagine, something that big that had never been seen before," scientist Edith A Widder, who recently left Harbor Branch, said in a telephone briefing.

When Katrina moved into the Gulf of Mexico the researchers retreated, first to Louisiana and then to Galveston, Texas. If the storm had continued west, Corpus Christi would have been the next stop, Captain Aric Anderson said.

They left the 90kg camera on the bottom. When they returned it had been upended, but they don't think that was done by the storm. The camera was 550m deep, where storm effects would be minimal.

They think a large predator probably upset the camera. Unfortunately the battery had run down so they didn't get a picture of it. They have filmed sharks attacking the camera before.

Previous studies of deep ocean life had used bright white light or looked at animals brought up in nets, Frank explained.

Unfortunately, the animals caught in nets are often badly damaged and the white light blinds these deep-sea creatures.

With the red light camera they have gotten pictures of animals and even been able to capture some and bring them to the surface without blinding them. They are kept in dark with only dim red light which they don't seem to be able to see.

The chambers are filled with cold seawater. The change in pressure doesn't seem to affect animals such as crabs and shrimp, which don't have air-filled swim bladders, the researchers said.

Some can see ultraviolet light, Frank said. They are trying to determine why. "As far as we know there is no ultraviolet light down there," she said. One theory is that it helps them see creatures that produce their own biological fluorescence.

"The discovery that one of deep-sea crabs has ultraviolet vision is thrilling," aid Witter. "The question is what the heck are they doing with it."

Some of the creatures also seem able to see polarised light, perhaps to help them detect camouflaged predators or prey.

Witter said the camera is often left for a few days with some bait, which attracts creatures into view.

A fake jellyfish that mimics the bioluminescent light of real jellies has attracted several squid attacks, they said.

As many as 80 percent of animals in the deep sea produce some light, she said.

Source: www.iol.co.za


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