In a segment from BBC's program The Hunt, I learned of a quite amazing animal: portia, a spider-hunting spider.
In the clip, you can see a portia approach another spider, twice her size, and then, stop and carefully think about the best approach route to take her prey. She finally picks a route that will take many, many minutes to complete, and which involves her being out of sight of the prey for a great deal of the route. And faced with unfamiliar spiders, they improvise new tactics. Furthermore, they are social, and recognize other individuals of their species.