I took a scuba diving course with an instructor who formerly worked as a diver with a local aquarium, and he related to us that the aquarium had to replace their octopus population every few weeks because they would keep dying of boredom, so to speak. They would put the food in hard-to-open enclosures, but it just wasn't enough. Octopuses need to be challenged and engaged. It gave us food for thought about whether we should be keeping creatures with such a powerful intellect in captivity.