I just uploaded two videos from swimming sea slugs. The first one is from Tritonia and the second is Melibe. Tritonia swims by flexing its body dorsoventrally and Melibe by flexing it sideways, like fish. The cool thing about this is that the behavior is controlled by homologous neurons in the same ganglia. Only the wiring is different, providing a great study case for the evolution of behavior.

Both videos were shot with the buil-in camera of my Palm Treo 650 smartphone.