London, October 15 : Seals have an oxygen reservoir within their muscles that enables them to dive underwater for up to 80 minutes at a time without taking a breath, according to a study.
Thomas Jue and his colleagues at the University of California, Davis, have discovered that seals' muscles contains 20 times as much myoglobin-a protein that stores and transfers oxygen within their cells-as humans.
The researchers believe that the way seals stop breathing for 20 minutes at a time while asleep on land helps them conserve energy.
During the study, the researchers measured the levels of deoxygenated myoglobin in two elephant seals as they fell asleep, and found that as the animals fell into a slumber and stopped breathing, their blood flow slowed.
"The metabolism drops," New Scientist magazine quoted Jue as saying.
He revealed that oxygen levels in the seals' myoglobin fell by 20 per cent within the first minute of sleep, as the cells used up their oxygen stores.
According to him, that freed myoglobin to pull more oxygen from the blood, stabilising the cells' oxygen level until the seals started breathing again.
Jue admited that the animals might use oxygen differently while diving, but added that the method was better than forcibly immersing seals in water, whereby "the animal exhibits the physiology of panic".