Magellanic penguins strut their stuff on the rocky shoreline of Argentina's Punta Tombo, home to the largest colony of the birds in the world. Craig Lovell/Corbis hide caption

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A drilling site rises from the middle of farmland near Fairfield, N.D. Many farmers and ranchers are profiting from the state's oil boom, but others complain that drillers are interfering with their business. Jeff Brady/NPR hide caption

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Piglets at Hilldale Farm in State Center, Iowa in March 2013, just before porcine epidemic diarrhea began spreading through hog farms in the U.S. Amy Mayer/Harvest Public Media hide caption

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The sexually transmitted cancer is common in street dogs around the world. Noel Celis/AFP/Getty Images hide caption

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A baby born too soon continues to develop and grow inside an incubator at the neonatal ward of the Centre Hospitalier de Lens in Lens, northern France. Philippe Huguen/AFP/Getty Images hide caption

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Each year, 6 to 8 percent of the global population of sharks and rays gets caught, scientists say. The fish can't reproduce fast enough to keep pace Mike Johnston/Flickr hide caption

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The round stingray is native to the eastern Pacific coast and is notorious for injuring swimmers and surfers. laszlo-photo/Flickr hide caption

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A northern spotted owl in a Redwood forest. Michael Nichols/Getty Images/National Geographic Creative hide caption

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