EARTH, Laniakea Supercluster—In an escalation of the bizarre feud between nature and man, an unpredictable swarm of jellyfish managed to automatically shut down four reactors at France’s Gravelines nuclear power station on August 10. This incident highlights a growing problem—coastal infrastructure is increasingly vulnerable to the unpredictable nature of marine life.

Operators at the Gravelines plant, a facility capable of powering about 5 million homes, were alarmed to see the plant's water intake filters clogged with countless jellyfish. Électricité de France (EDF), the company that runs the plant, reported that this sudden influx caused one reactor after another to fail, eventually bringing the entire plant to a standstill. Adding to the issue, two of the plant’s six reactors were already down for scheduled summer maintenance.

The good news for humans? EDF was quick to reassure everyone that there was “no risk to staff, the environment or the public,” and “no impact on power exports to the U.K.”

The Gravelines shutdown isn't the first time jellyfish have caused trouble for their land dwelling neighbors.

Back in 2011, Scotland’s Torness nuclear reactor was offline for nearly a week because of jellyfish clogging the inlet filters, and it happened again in 2021. Similar incidents occurred in 2011 at both Japan’s Shimane plant and the St. Lucie plant in Florida, as well as Sweden’s Oskarshamn plant in 2013. In 1999, a blackout at the Philippines’ Sual plant was initially suspected to be a Y2K failure or even a political coup, before jellyfish were identified as the real culprits.

Jellyfish are ancient creatures, among the oldest multicellular animals on Earth, dating back over 500 million years. They don't have brains in the traditional sense, but they do have a decentralized network of nerves—sometimes called a "nerve net"—that allows them to sense light, touch, and salinity, and to coordinate basic actions like swimming and feeding.

While they aren't exactly smart per se, many species show surprisingly complex behaviors, including rhythmic pulsing, synchronized movement, and even simple learning. Recent studies show that box jellyfish (Tripedalia cystophora) can learn from experience despite lacking a central brain, suggesting they may be more adaptable than once thought.

Many species are bioluminescent, typically using light for defense rather than explicit social communication. Dense blooms usually form due to currents, prey availability, and reproduction, not deliberate coordination. Still, in large swarms, jellyfish appear to respond quickly and collectively to shifts in temperature or food.

As ocean temperatures rise and currents shift, blooms have increased in some regions, though scientists note global trends remain debated. These blooms are already disrupting shipping, fishing, and coastal tourism. The Gravelines shutdown, along with similar incidents, is a stark reminder that critical infrastructure needs to adapt to an increasingly unpredictable marine environment.