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Wednesday, 14 March, 2001, 20:44 GMT
Dumbo 'needs big ears'
Elephant graphic BBC
If Dumbo the elephant were real he would have needed to flap his huge ears not just to fly but also to stop him overheating.

So say two US scientists who became intrigued by the cartoon character while exploring how elephants cool themselves down by pumping blood through their ears.

He needs big ears not just to fly but to lose the extra heat he produces while flying

Polly Phillips, University of Illinois
Calculations of Dumbo's dimensions reveal that his large appendages would have stopped him suffering from severe heat stress.

But his cooling system was so efficient that he would have died of hypothermia if he rested for too long.

The unusual study was carried out by biologists Polly Phillips and James Heath of the University of Illinois in Urbana-Champaign. Using drawings supplied by Walt Disney, they worked out the likely surface area of Dumbo's ears and calculated how much heat he would have produced.

Heat stress

They estimated that during flight, his metabolic rate would have been 10 times that of his resting rate.

If Dumbo's ears were any smaller, he would suffer crippling heat stress while flying, the researchers told New Scientist magazine.

"We conclude that he needs big ears not just to fly but to lose the extra heat he produces while flying," said Phillips.

The downside was that in cooler weather, Dumbo "could actually lose more (heat) than he produces," which meant he could have died of hypothermia while resting.

The study also has a serious side in that it provides insights into animal physiology.

A real elephant with Dumbo-sized ears would be doomed, as it would need to have an enormous metabolic rate - and a huge food intake - to compensate for the loss of heat from its ears.

The research is published in full in the Journal of Thermal Biology.

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