Scientists have gathered conclusive proof that whale sharks justify their "whale" tag - by diving to depths of up to 1000m, just like many of their mammalian counterparts.

Researchers based in Belize managed to tag a number of the animals off the Belize Barrier Reef. The sophisticated electronic tags recorded water pressure (from which depth could be correlated), temperature and light levels. After a predetermined period, the tags detached and floated to the surface, where they relayed their data back to base via satellite.

That information told the scientists that the whale sharks had dived to depths exceeding 1000m, to feed on swathes of eggs released by spawning shoals of fish. The animals' general living pattern was to stay shallow during the night, feeding off plankton, but to dive deeper in hotter daytime conditions for the egg spawns.

It was also revealed that water temperature at depth could fall to only just above freezing. This would explain why whale sharks, even in tropical waters, have a layer of insulating fat under their skins.

The information gathered by the scientists confirmed the importance that the whale sharks regularly attached to finding and feeding on fish spawnings. This led to the conclusion that maintaining healthy fish populations and spawning patterns was important in sustaining populations of the whale sharks.

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