How do marine invertebrates move about?

Many species of invertebrates are sessile, which means that they do not move, but remain anchored in the same spot their whole lives.  However, there are also many species that move around.  Marine invertebrates have different forms of locomotion, depending on the species.  Many are bottom-dwellers, which means that they crawl along, either on feet or tube feet or a single large muscular foot, in search of food.  Many other swim using fins, jet propulsion, or some other means of propelling themselves through the water.