An octopus uses several methods to move through the ocean. An octopus in a hurry uses jet propulsion by rapidly contracting its water-filled mantle, the muscular sac that encloses its gills and body organs. The contracting mantle forces water rapidly through a funnel at its base, propelling the octopus in the opposite direction. Slower movement is achieved by using all eight limbs to maneuver along the sea bottom or around obstacles.
An octopus can change the direction of its mantle funnel, enabling it to propel itself forward or backward. This ability to control the funnel also enables the animal to change directions quickly. The fastest movement is backward.
Octopus limbs are equipped with adhesive suction disks. The animal uses its limbs and suction disks to pull and push itself along the ocean bottom, around rocks or into and out of small spaces. An octopus can squeeze through any opening large enough to accommodate its eye. The octopus methodically lengthens and compresses its limbs and body to move itself through a tight spot.
In addition to rapid movement, octopuses defend themselves by ejecting a dark liquid from their ink glands to create a somewhat toxic and unpleasant decoy that generally allows it to propel itself quickly away from the distracted danger.
Octopuses prefer crawling along the bottom of the sea and reserve swimming for escape maneuvers. Octopuses have three hearts; one circulates blood through the organs and the other two keep blood circulating around the gills. When the octopus is moving rapidly using its jet propulsion system, the heart supplying the organs stops for the duration, so swimming rapidly for any length of time causes exhaustion.