Like other octopuses, the Pacific giant octopus is extremely intelligent and has been observed opening jars and are even known to recognize caregivers in captivity. This makes sense considering they have nine brains! They also have eight arms and three hearts. Two of the three hearts pump blood to the gills, while the third circulates blood to the rest of the body. Octopuses use one central brain to control their nervous systems and a small brain in each arm to control movement. They’re also known for having blue blood thanks to a copper-rich protein called hemocyanin in their bloodstream, which is used for oxygen transport.