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Soon the males and the pups will follow her into the water—and this is where the elephant seal reveals itself to be one of the most perfectly adapted predators on Earth. While offshore the seals make journeys of more than 8,000 miles and dive as deep as 5,000 feet, beyond the range of most submarines. For months they hunt for squid and fish, searching for where currents deliver the most nutrients, which in turn attract the rest of the food chain. They can remain submerged for as long as two hours and need only a few minutes of surface time to recover. All this is made possible by some nifty physiological tricks that include shutting off parts of their metabolism to conserve oxygen. Elephant seals are packed with oxygen-rich blood—20 percent of their bodies by volume, almost three times as much as humans.

Given the difficulties of studying a creature that can be found a mile beneath Antarctic sea ice, scientists have recently begun to affix satellite tags to the seals. Along with tracking the animals' movements, the tags deliver an added benefit: They're helping oceanographers figure out the effects of climate change. "There's a real worry right now that ocean-circulation patterns might be changing," Fedak says, describing a scenario that would have massive repercussions for the Earth's weather. "The Southern Ocean plays a critical role in this, and yet it's one of the most data-poor areas. These animals are able to take the devices into places that are unsampled otherwise." Information about water temperature, salinity, and currents in some of the Southern Ocean's least accessible areas is now pouring into the five-year-old Southern Elephant Seals as Oceanographic Samplers program.

So never mind the wacky nose and ungainly body. Gliding beneath a blue icescape, the southern elephant seal is not just going about its business. Like any self-respecting superhero, it's helping save the planet.

Susan Casey is the author of The Devil's Teeth, about great white sharks. Yva Momatiuk and John Eastcott photographed the wolves of Denali for their most recent feature in the magazine.
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