Will Jellyfish Take Over the World?

Are jellyfish massing against humankind? Not really; it just seems that way. They may be sending us a message, though.

Enormous aggregations of the diaphanous sea creatures have been wreaking havoc from shore to shore -- clogging water intake valves on seaside power plants, destroying fish farms, crowding fishing nets and, yes, stinging people (sometimes fatally). It’s nothing personal. Jellyfish, lacking brains, do not wish us harm. They’re merely going about their lives as they have for more than half a billion years: swimming, eating and reproducing, lately in mind-boggling numbers.