An octopus’s body contains 500m neurons, roughly the same as a dog’s, but most of these reside in the cephalopod’s arms and allow the tentacles to act independently from the brain (their arms literally have a life of their own). The type of consciousness experienced by an octopus, then, is wholly alien to humans.

Early experiments assumed that the intelligence of animals could be estimated by their ability to carry out tasks, such as learning to pull a lever in exchange for food. Octopuses perform quite well in such tests but not as well as rats. Yet it is the anecdotes buried in research papers or related to him by scientists who work with animals that Mr Godfrey-Smith contends are often more revealing than the experiments themselves. One researcher told him of an octopus that expressed its displeasure with the lab food by waiting until she was looking before stuffing the unwanted scrap of squid down the drain.

Source: https://goo.gl/UqonrB