An octopus has three hearts. The first, largest and strongest heart is located in the middle of the body, while the other two hearts are located on either side of the gills and are responsible for pumping blood to the gills on each side.
An octopus has nine brains. The first, larger one is located inside the head. The remaining 8 brains each have a brain in each claw, which means that each claw can 'think' on its own.