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.

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.