Octopuses may have nightmares about predators attacking them

Octopuses may have nightmares. That is one possible explanation for some extraordinary behaviour caught by cameras monitoring an octopus in a laboratory aquarium, says Marcelo Magnasco at the Rockefeller University in New York.

In 2021, his team bought an octopus (Octopus insularis) caught off Florida for their studies of cephalopod cognition. The octopus, named Costello after one of the “heptapod” aliens in the film Arrival, rapidly adapted to captivity and began sleeping out in the open, rather than in a den as octopuses do in the wild.

One morning, team member Eric Ramos, also at the Rockefeller University, entered …