NarwhalsAmong all the large whales on Earth, the most unusual and least studied is the narwhal, the northernmost whale on the planet and the one most threatened by global warming. Narwhals thrive in the fjords and inlets of northern Canada and Greenland. These elusive whales, whose long tusks were the stuff of medieval European myths and Inuit legends, are uniquely adapted to the Arctic ecosystem and are able to dive below thick sheets of ice to depths of up