The coconut octopus has a closed circulatory system. Octopuses have one main heart, called the systemic heart, and two smaller hears near the gills, in which the two smaller gills pump blood to the gills where oxygen is provided and wastes are collected and eventually eliminated from the body. The main heart pumps oxygen-rich blood throughout the body of the octopus. Also, the blood in the octopus contains hemocyanin, causing the blood to be blue.