From biomesblog: "How smart are octopi? We taught her this trick in about an hour. First you place an empty glass jar in her tank. Because they are so curious she will investigate it and realize it's not a threat. Next, you place a crab inside the jar, but without a cover on it. She of course will see the crab and simply reach in and grab the food. Then you place the cover on the jar and barely turn to secure it. She'll figure out that by twisting the cap a bit it will come off and she gets the food. Finally, you screw the cap on and let her go at it."