What makes the octopus nervous system so different?

Octopus have neurons in their arms as well as their brain. The Octopus nervous system is divided into three main parts: A central brain, two optic lobes, and the peripheral nervous system of the arms. The eight arms of an octopus contains two-thirds (a majority) of the octopus’s total 500 million nerve cells, allowing for special motor and sensory processing within the arms. Octopuses are highly intelligent in a variety of ways: showing an ability of long and short-term memory, pattern and shape recognition, tool use, play, and problem solving.