Trait shifts may linger long after a predator is gone (Turner and Montgomery, 2003). Because the shift in activity had not been drastic in the presence of the moray eel, the octopuses might have been able to start returning to their baseline activity phasing in the predicted three days after the predator had been taken out of the tank, while the return to the baseline would have probably taken a longer time after the removal of the triggerfish. Future studies should try to tackle not only different species of predators but also focus on how octopuses will respond to transient acute threat versus chronic exposure to threats. The present study shows for the first time that O. vulgaris is among those adaptable and flexible animals that are able to adjust their activity in response to threat/competition by other predators. While most animals are either classified as nocturnal or diurnal ( Dunlap et al., 2004) O. vulgaris is apparently able to function equally well at both times of day, and therefore possesses the ability to switch between them.