I use the term run lightly, however it kind of looks like they are waddling back and forth rather than swimming doesn't it? Scallop swimming is very funny, much funnier on video than it is when your actually underwater. This video was taken from one of our planting sites for the restoration effort in the peconics. While all bay scallops possess the ability to swim, and many do, for some reason, the scallops at this particular site seem to do it all the time. It might be a water quality thing, as the clarity here is typically lower than that at other sites we plant, but whatever the reason is, its always a fun dive.
For some reason I cannot seem to post the long video, its not loading. You can try to view it here. See if you can spot the little seed scallop swimming up off the bottom (its ok if you don't, I had to watch 3 times to see it). Also notice the healthy scallops in a habitat dominated by macroalgae and no eelgrass. Interesting, isn't it?