Before revision:  The swimmer exhibits a rich behavior: it can settle into a straight trajectory in the channel , or can navigate from one wall to the other , depending on confinement. Furthermore, the nature of the swimmer is  found to be affected by the confinement: the swimmer can behave  as a pusher at low confinement, and becomes a puller at higher confinement , or vice versa;
After revision:  The swimmer exhibits a rich behavior: it can settle into a straight trajectory in the channel , or can navigate from one wall to the other depending on its confinement. The nature of the swimmer is found to be affected by the confinement: the swimmer can behave as a pusher at low confinement, and becomes a puller at higher confinement , or vice versa;