It takes a lot of work to get where I want to go. I don't move very quickly, but think about how fast you would go if you had to slide around on your tummy.
I use some of my muscles and my setae (bristles, remember). My setae act like the brakes on a car, helping me to slow down or stop. I have muscles that go in circles around my body and other muscles that run the length of my body.
Actually, I'm pretty well-built, if I do say so myself. When my circular muscles tighten up, my body becomes thinner and longer. I sort of look like two birds are pulling me from each end.
(Now that's a scary thought. Let me take a minute to calm myself down....whew! Now where were we ... oh, yeah, moving right along.)
This movement by my circular muscles squeezes my front end forward. My other long muscles squeeze together and help move the rear end of my body towards the front end. So this is how I move forwards and backwards. Pretty slick.