On the contrary, octopi have an extremely advanced nervous system compared to other invertebrates. Their brains are large and they form from a fusion of ganglia. Muscle contractions, sensory perception, memory and decision-making processes have a very large portion of the brain devoted to these processes. This allows the octopus to be a very smart animal that is able to learn and problem solve. Studies have found that an octopus can learn by watching other octopi, called observational learning. Not only are octopi smart animals they also have a very keen sense of sight. As a matter of fact their sight is somewhat like humans. One-way in particular their sight is better than ours is how the optic nerve is connected. The optic nerve is connected to the back of the retina in octopi, which allows the octopi to have no blind spots. Humans on the other hand have a blind spot because of the placement of the optic nerve. An octopus can make out shapes and some colors.
When feeding, octopi use their sense of sight to find their prey and their tentacles to catch the prey. The suction cups that line the tentacles are very sensitive to the touch. The tentacles have suction cups covering the bottom side of them, which allows them to grasp onto objects. Some of the suction cups may also contain protein. The protein helps to reinforce the suction cups, and small hooks help to aid in holding onto objects. Mastication is performed with a jaw and a radula. The jaws actually tear the food and the radula grasps the food and forces it into the mouth. Octopuses hunt for snails, fish, and crustaceans. They are nocturnal hunters. In some cases venom from salivary glands help to immobilize their prey so the may eat their prey more easily.
Chromatophores are cells that contain pigment. These cells give the octopus the ability to change color depending on the mood of the octopus. Chromatophores also help the animal blend in with its surroundings so that it may be camouflaged and harder to be found. This sometimes happens in correlation with a discharge of ink from the ink gland. The ink helps to allow the octopus to escape danger. The ink blinds their predator and it can help to disorient it long enough for a getaway. The ink can also be poisonous to other animals as well as itself if exposed long enough.