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BUILT FOR THE EXTREMEIf there is one creature on Earth that looks and acts like an alien, at least among animals with backbones, Kooyman believes it's the emperor penguin. The bird thrives in a climate marked by bone-rattling winds, temperatures that often reach colder than -34 degrees C (30 degrees below zero F) and winter darkness that may prevail for three months. As part of its breeding process, the emperor penguin undergoes periods of extreme weight gain, accumulating an extra 30 to 50 percent of body mass in about five weeks. The additional 15- to 20-kilogram (33- to 44-pound) gain is a prerequisite for its body to endure several months of fasting. But it was the animal's physiological capability as an extreme diver that initially grabbed Kooyman and Ponganis's interest. From previous reports and their own observations, Kooyman and Ponganis knew emperors could dive deeply in search of food. In 1969, Kooyman measured an emperor diving to 265 meters (870 feet). The advent of the microprocessor and instrument miniaturization in the 1980s further expanded their investigations. Instead of crude data focused on a single dive in 1969, they now employed instruments that could record many weeks worth of diving profiles in detail.  
In the early 1990s, Kooyman began attaching microprocessor-based time-depth recorders to the animals' bodies to gauge their diving capacities. Kooyman, his son Tory, and colleagues measured dives to an astounding 500 meters (1,640 feet) and beyond. Around the same time, Kooyman and Ponganis became interested in the penguins' oxygen consumption during these dives, clocked as long as 22 minutes in a single breath. These studies were particularly intriguing for Ponganis, a physician who spends half his life as a practicing medical anesthesiologist, an occupation in which oxygen delivery to the patient is crucial. Kooyman and Ponganis's research has begun to unveil the secrets of emperor penguins' physiological advantages. Track and field sprinters, for example, power their need for speed through glycolysis, in which their muscles break down glycogen to lactate to release bursts of energy. While instantaneous, the process is taxing on muscles. The smooth hydrodynamic efficiencies in emperor penguins' body design allows them to stroke and glide through the water with speed and efficiency at low metabolic rates, thereby delaying glycolysis much longer than any human could. Emperors also must be the envy of marathon runners, who rely on a long, steady delivery of oxygen from the lungs through the blood to muscles. The penguins boast extremely high concentrations of myoglobin, a protein found in muscle that stores oxygen throughout their bodies. Thus they don't rely on an oxygen delivery process as humans do rather, the oxygen is already there in the muscles. Because of this and other delivery and storage adaptations, emperors can draw down blood oxygen stores to a level approaching zero, well past the threshold of consciousness in humans.  
"It's a remarkable capacity," said Ponganis. "If there are more fish to be had, emperor penguins are going to make the dive longer and go after all they can." Ponganis believes that knowledge of such adaptations can hold promise for not only understanding the biology of the emperor penguin but for human health and medicine. "If we can understand why these animals can function at such low oxygen levels on a biochemical or molecular basis," says Ponganis, "it could be relevant in how we can avoid tissue damage when patients experience low oxygen levels in their tissues, whether it's due to a stroke or heart attack." Next page: An iceberg destroys a penguin nesting habitat |
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:: © 2009 Scripps Institution of Oceanography, University of California, San Diego. All Rights Reserved.
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