Whales make calls for a number of reasons—to navigate, to find food, to communicate with each other—and for certain whales, like humpbacks and blues, songs also seem to play a role in sexual selection. Blue males sing louder than females, and the volume of their singing—at more than 180 decibels—makes them the loudest animals in the world. They click and grunt and trill and hum and moan. They sound like foghorns. Their calls can travel thousands of miles through the ocean.

The whale that Joe George and Velma Ronquille heard was an anomaly: His sound patterns were recognizable as those of a blue whale, but his frequency was unheard-of. It was absolutely unprecedented. So they paid attention. They kept tracking him for years, every migration season, as he made his way south from Alaska to Mexico. His path wasn’t unusual, only his song—and the fact that they never detected any other whales around him. He always seemed to be alone.

So this whale was calling out high, and he was calling out to no one—or at least, no one seemed to be answering. The acoustic technicians would come to call him 52 Blue.

Leslie Jamison, in a Slate excerpt of her new Atavist book, 52 Blue.

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Photo: hmj, Flickr