a girl exclaims. “I think they’re just mesmerizing,” Jennie Janssen, the assistant curator who oversees the care of the aquarium’s jellyfish, tells me. “They don’t have a brain, ...

Jellyfish are known for drifting to and fro at the whim of ocean currents—but not all species are so passive. The millions of golden jellyfish that pack Palau’s Jellyfish Lake spend much of ...