Biology provides many examples of where body adaption can be used to achieve a change in functionality. The feather star, an underwater crinoid which uses feather arms to locomote and feed, is one such system; it releases its arms to distract prey and vary the maneuverability to help escape prey. Using this crinoid as inspiration, we develop a robotic system that can alter the interaction with the environment by changing its morphology. We propose a robot that can actuate layers of flexible feathers and detach them at will. We first optimize the geometric and control parameters for a flexible feather using a hydrodynamic simulation followed by physical experiments. Secondly, we provide a theoretical framework for understanding how body change affects the controllability. Thirdly we present a novel design of a soft swimming robot with the ability of changing its morphology. Using this optimized feather and theoretical framework, we demonstrate on a robotic setup how the detachment of feathers can be used to change the motion path whilst maintaining the same low level controller.