"So you're a pregnant manta ray, and you're about to give birth to a baby with, oh, a six-foot wingspan. How on Earth will you manage that? Now, for the first time, scientists can answer that question: You gently flap your glorious, 13-foot-wide wings to swim to the bottom. You rub your swollen belly on the ground for a while. Then you gain a little altitude and, with a forceful push, you eject your precious bundle as a rolled-up, burrito-like tube, which promptly unfurls to begin its new life