Emperor Penguins are able to dive to depths of over 500 m and stay under water for up to 27 minutes - deeper and longer than any of its fellow avian species, scientists have found.
Researchers from the University of California, Alexandra Wright and Dr Paul Ponganis, investigated the heart rate response of Emperor Penguins as they made foraging trips to see from the Cape Washington Colony in Antarctica.
They measured heart rates using an electrocardiogram (ECG) recorder and looked at dive behaviour with a time depth recorder (TDR) and found that the penguins slow their heart from the normal rate of around 70 beats per minute to as low as 10 beats per minute.
Emperor Penguins also have unusually structured hemoglobin to allow it to function at low oxygen levels, solid bones to reduce barotrauma - physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with the body and the surrounding fluid.
They also have the ability to reduce metabolism and to shut down non-essential organ functions.
The profound decline in heart rate - known as bradycardia - decreases oxygen consumption, conserves the respiratory and blood oxygen stores, and isolates muscle, which must rely instead on its own oxygen store which is bound to the muscle protein, myoglobin.
Although this heart rate response contrasts with other birds and terrestrial mammals, it is similar to the dive response of marine mammals.
The findings will be presented at the International Penguin Conference (IPC) in Bristol this week.
