Squids and octopuses, both cephalopods, are the most intelligent known invertebrates. Direct comparison of squid and octopus intelligence is not feasible, as squid are much more difficult to keep in laboratories for study.
Octopuses use tools, recognize human caretakers, display varied hunting tactics and have problem-solving capabilities. They exhibit behavior suggesting planning and foresight, such as raiding humans' crab and lobster traps and climbing aboard fishing boats carrying containers of crabs. Sy Montgomerty of Orion magazine reported an experiment that observed a female octopus playing with a pill bottle. Squid exhibit complex social signaling and one species, the Humboldt squid, engages in cooperative hunting.