Jellyfish shut down a nuclear power plant in Sweden this week, which you’d think might be big news, except that jellyfish shut down nuclear plants a LOT. “Jellyfish clogs are a recurring problem,” say the New York Times. “Mr. Osterberg noted that the plant had a similar episode in 2005.”

It’s taken decades, but the jellyfish have perfected this guerrilla protest technique. It’s not clear if they’ve coordinated with Greenpeace, or other groups. But Grist can report that terrorist jellyfish actions have increased in size and frequency.

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1937: Jellyfish shut down a power plant in Australia. It takes them awhile to realize what they can do with this power. They spend years clogging up, but not stopping, the filters in Japanese power plants, before finally making their move.

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1989: 4 million jellyfish were removed from a plant in Madras. They weighed about 80 tons.

1999: Jellyfish blacked out electricity for 40 million people in the Philippines, after clogging up a coal-fired plant.

2006: Thousands of jellyfish shut down a nuclear power plant on a U.S. warship while it was docked in Brisbane, Australia.

2011: The year that jellyfish start taking this work seriously. Scotland and Japan both suffered attacks. In Israel, power plant workers had to remove 100 tons of jellyfish.

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But like Douglas Adams always said: Don’t panic. (Of course, with Douglas Adams the hyper-intelligent creatures were mice and dolphins, none of which can inject you with neurotoxins.) Wired talked to a jellyfish expert, who said this isn’t a jellyfish plot, exactly:

“We’re a long ways from jellyfish taking over the world, but humans are changing food webs in the ocean by our activities,” Steinberg said. “It’s an experiment, a big experiment, and we don’t know yet what the outcome is going to be. We need to be careful.”

Oh. That’s worse. We’re doing this to ourselves. Maybe panic.