Harbour seal
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How sea mammals hold their breath

Scientists say they have solved the mystery of one of the most extreme adaptations in the animal kingdom: how marine mammals store enough oxygen to hold their breath for up to an hour.

The team studied myoglobin, an oxygen-storing protein in mammals' muscles and found that, in whales and seals, it has special "non-stick" properties.

This allowed the animals to pack huge amounts of oxygen into their muscles without "clogging them up".

Their findings are published in the journal Science.

Victoria Gill reports.