 In doing so, it uses a jet mechanism that involves creating a much higher pressure in its mantle cavity that allows it to propel itself through the water.As the common octopus' heart and gills are located within its mantle, this high pressure also constricts and puts constraints on the various vessels that are returning blood to the heart.Ultimately, this creates circulation issues and is not a sustainable form of transportation, as the octopus cannot attain an oxygen intake that can balance the metabolic demands of maximum exertion.