Photo by joelsartore | North American river otters are built for life on the water. Thick, protective fur keeps them warm as they navigate chilly waters; short legs and webbed feet make them incredibly fast swimmers; and a long, narrow body and flattened head help streamline their movements. Otters like this one wildlifecenterastoria are also capable of staying underwater for up to eight minutes, during which time they can use their long whiskers to help them detect prey. To see more species featured in the Photo Ark, follow me joelsartore. #PhotoArk #WorldOtterDay