When they feel the need for speed, cephalopods propel themselves through the water using jet propulsion. For jet propulsion to occur, water flows into the mantle cavity and over the gills through an opening by the head. The mantle builds internal pressure by sealing off all orifices, with the exception of a tube called the funnel or siphon. The thick muscles of the mantle wall contract, squeezing water out of the narrow funnel with enough force to propel the animal in a speedy burst, similar to the way a balloon will whiz through the air when the knot is untied. Squid are the fastest marine invertebrates, using jet propulsion to swim more than 25 miles an hour. At this speed they could keep pace with lithe mammals such as coyotes, snowshoe hares, and leopard seals.
Cephalopods steer by adjusting the direction of the funnel. To escape from a predator, a squid would point its water jet forward to propel itself backward, away from the threat. By pointing the funnel backward, the same squid can move forward, allowing it to pounce on prey. Some species use their funnels as water guns, shooting jets of water to agitate predators or prey.Other modes of locomotion include:
Benthic octopuses use their arms to walk across the ocean bottom.They pull themselves along using rows of adhesive suckers along the underside of their arms.
Fins provide balance and propulsion in squid, cuttlefish, and some finned octopuses. Fin swimming is often used in conjunction with jet propulsion.
A few species of squid escape from predators by blasting themselves out of the water with a burst from the funnel and traveling through the air for distances up to 200 feet. Squid have small fins that stabilize flight and allow them to glide above the water's surface. Neon flying squid, (Ommastrephes bartrami) which often swim in schools, have been observed flying in groups of more than one hundred. The Humboldt squid, sometimes known as the jumbo squid, are also capable of flight.