Otto the octopus didn’t appreciate the spotlight shining on his laboratory tank at night. So he turned it off. In fact, he turned off the lights in the whole lab.

Octopuses are smart and curious. They use tools and learn from watching other octopuses. They can solve mazes, open the lids of glass jars, and build dens.

In the lab, they learn to tell people apart. They’ve been known to take a disliking to some of the lab workers, squirting jets of water at them when they walk by. And they can show a clear preference for the people who feed them.

Octopuses also play. In one study, scientists put some small, sealed plastic bottles in octopus tanks. Some of the critters fired jets of water at the bottles, bouncing them off the walls. Others fired a bottle toward the tank’s inlet valve, so the bottle came back to them—like octopus ping-pong.

And that brings us back to Otto. Scientists in Germany were studying the behavior of Otto and several others. Otto was the most active. He damaged the glass walls of his tank by throwing rocks at them, and he sometimes rearranged the stuff in the tank.

A 2,000-watt spotlight shined on the tank at night. But several times, the light shorted out—and so did the rest of the lab. Scientists then spent the night in the lab to figure out what was happening. Otto was climbing to the rim of the tank and squirting water at the light. That turned out the lights—perhaps allowing Otto to get a good night’s sleep.