Seals' muscles hide a built-in scuba tank

AN OXYGEN reservoir within seals' muscles could explain how they can dive underwater for up to 80 minutes at a time without taking a breath.

Seal muscle contains 20 times as much myoglobin - a protein that stores and transfers oxygen within their cells - as humans. Seals also stop breathing for 20 minutes at a time while asleep on land, which probably helps them conserve energy.

Thomas Jue of the University of California, Davis, and his team measured the levels of deoxygenated myoglobin in two elephant seals as they fell asleep. They found that as the animals fell into a slumber and stopped breathing, their blood flow slowed. "The metabolism drops," says Jue...[NewScientist]