Although an octopus has eight arms, or tentacles, it does not use them for swimming. These tentacles are only for crawling along the ocean floor and for catching food.
In order to move through the water, the octopus draws water into a cavity in its body, then squirts it out in jets through a tube, or siphon, just under its head. The force of this squirting is so powerful that it moves the octopus swiftly backwards through the water, in an action similar to jet propulsion.
If one of an octopus’ tentacles is cut off, a new one grows in its place!