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Monday, 25 February, 2002, 08:56 GMT
Sealcams reveal underwater world
The camera is strapped to the seal
The cameras are about the size of a tennis ball
Small video cameras attached to seals are giving researchers an insight into the underwater world of the Antarctic.

The scientists equipped 15 Weddell seals over the course of three Antarctic summers with video cameras and data recorders to track both their movements and learn how they hunted their prey.

"At this point, almost everything we are seeing is new and exciting," said Randall Davis of Texas A&M University, who is leading the project.

"What we are now discovering is some of the strategies that these animals use to search, detect and capture their prey," he told the BBC programme Go Digital.

The project is now providing a rare glimpse into the habits of two important Southern Ocean species: the Antarctic silverfish and the Antarctic toothfish.

'Biological platform'

The problem facing the researchers was how to watch a Weddell seal hunting once it disappears below the ice and plunges to great depths.

Dr Randall Davis is leading the research
Dr Davis: Seeing new and exciting things
For the solution, they came up with the use of sealcams.

"Seals can out swim a submarine so the idea of using a submarine doesn't really work for these species," explained Dr Davis.

"Instead, what we've done is turn the animal into a biological platform, so we let the animal collect the data on its own behaviour, environment and its prey."

The self-contained camera and data recorder are about the size of a tennis ball. They are attached by straps to a piece of neoprene rubber that is glued to the head of the seal.

The unit is removed after about a week.

Learning about fish

The sealcams have provided a valuable insight into a previously secret world.

"We now have confirmed that during the summer these seals appear to dive while looking up and silhouetting fish against the daylight," said Dr Davis.

Seals are hard to track under water
Little was known of the seals' underwater habits
"Once they detect a school of fish, they stop descending and will ascend through the school and capture a great many of these fish."

Although the researchers' original plan was simply to learn more about seal hunting behaviour, the results have shed light on two unfamiliar species: the Antarctic's silverfish and toothfish.

Researchers now believe, based on the sealcam data, that the silverfish migrate from deeper to shallower water using ambient light, even in the absence of a sunset during the Antarctic summer.

The success of the sealcam technique, say the scientists, means it could be used to study other animals that are otherwise impossible to observe in their natural environment.

In the future, Dr Davis and his team hope to use a similar technique to learn more about elephant seals, small whales and dolphins.

Dr Randall Davis
Discovering how seals hunt and capture their prey
See also:

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27 Jan 99 | Sci/Tech
Ice cool in Antarctica
06 Apr 00 | Sci/Tech
Mammal cam reveals diving secrets
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