The octopus is generally acknowledged to be the most intelligent invertebrate in the world. Octopus relates both what is known and unknown about the mind of an octopus, as well as detailing the animal's remarkable natural history. Octopus also documents the long and multi-faceted relationship between human and cephalopod. It shows how over millennia some cultures have regarded octopuses as erotic totems, while others have considered them symbols of the darkest evil, or nothing more than a tasty meal.