It all began with a simple question: Why don’t manta rays clear their throats? The car-size, kite-shaped fishes filter their plankton food from seawater, but they don’t pause, close their mouths and ...

Many years ago, I was snorkeling in warm Pacific waters when I noticed what looked like a spreading ink stain in the water before me. It was faint at first, a barely perceptible sliver of black ...