Cardiovascular System
The blue ringed octopus has a closed cardiovascular system. However, it also has an interesting feature in that it has 3 different hearts as part of this system. This includes the main systematic heart, and two smaller hearts. These smaller hearts are located near the octopus' gills. The smaller hearts pump blood to the gills to remove waste and add oxygen to it. The oxygen rich blood then moves to the systematic heart, which pumps it through the rest of the body. Different proteins known as hemocyanin give the blood a blue color within this system.