Scientists saw unusual behaviour in an octopus. They say it looked like it was waking up from a nightmare.
The octopus, named Costello, was filmed 24 hours a day in a laboratory in New York over the course of a month.
On four occasions, Costello awoke abruptly before engaging "in predatory behaviours," changing colour, and waving his arms around, the scientists said.
Twice, the octopus shot black ink into the water – a common tactic used to escape from predators – even though there was no predator nearby.
The behaviour suggested he was responding to a bad dream.
"It was really bizarre, because it looked like he was in pain for a moment," says Eric Ramos, one of the scientists. "And then he just got up like nothing had happened, and he resumed his day as normal."
The study only observed one octopus, but it raises interesting questions about the dream experiences of these intelligent creatures.
