There are also more subtle psychological similarities. Octopuses, like us, seem to have a distinction between short-term and long-term memory. They engage in play with novel objects that aren’t food and have no apparent use. They seem to have something like sleep. Cuttlefish appear to have a form of rapid eye movement (REM) sleep, like the sleep in which we dream. (It’s still unclear whether there’s REM-like sleep in octopuses.)
