The softness of robots that navigate the real world is frequently hamstrung by rigid elements such as traditional computers. One avenue that may reduce the reliance on these types of devices is the application of physical reservoir computing (PRC). Previous studies have shown that by leveraging the under-actuated nonlinear dynamics of soft mechanisms, complex computing tasks can be achieved. In this study we present a new octopus-inspired walking and swimming robot: Takorobo. We investigated the degree to which locomotion significant tasks (including body motion prediction and direct actuator control) can be embedded into this robot using its four soft sensory tentacles. The robot was found to be able to accurately compute its body motions and successfully exercise direct closed-loop PRC control on both land and water for some control signals.