Along with eight arms, an octopus also has three hearts and nine brains. 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. Octopuses, including the giant Pacific octopus, are also known for having blue blood thanks to a copper-rich protein called hemocyanin in their bloodstream, which is efficient for oxygen transport in cold ocean environments.
Giant Pacific octopuses only live an average four to five years in the wild, yet they are still considered one of the longest-living octopus species. Octopuses typically die shortly following breeding. After mating, a female will lay up to 74,000 eggs or more in a deep den or cave and live there for seven months watching over them. During this time, dedicated mothers won’t venture out for food, and shortly after the young hatch, the mother will die. Because of this behavior, it is difficult to know population numbers of the giant Pacific octopus. Even though these octopuses are still commercially fished in both North America and Japan for food and bait, populations have been naturally resilient so far.