|An octopus jets across the ocean floor. Fwooosh!|
Photo: Albert Kok, Wikimedia
Especially when they typically move through the water by jet propulsion.
Octopuses (octopi?), like other cephalopods, have both a mouth, which sits in the center of their arms, and a tube-shaped organ called a funnel, or siphon, near their heads, that they use to breathe by bringing oxygenated water to their gills.
They also use the siphon to create their own personal jet propulsion, by filling up their muscular mantle cavity (their body, basically) with water and then quickly expelling the water out of the siphon. Fwoooosh.
The force of the water jet coming out of the siphon sends the cephalopod jetting away in the opposite direction, like a rocket -- useful for escaping danger or jumping onto unsuspecting prey. Cephalopods can change the direction and speed of their jet propulsion by pointing the siphon in different directions and varying the speed at which they "spit" out water.
However, stealth and camouflage are their primary means of both attack and defense, and jetting around makes hiding impossible. So some octopuses run. On two legs. Backwards. Using their other 6 arms to provide camouflage.
In other words, they can backpedal away from predators while remaining camouflaged, like sea dragons and other camouflaged sea creatures. Have a look!
Learn more about this movement from Dr. Chrissy Huffard, who first discovered it.