Fig. 5. Shape sensing of underwater manta ray fin. a, Overview of the fin profile, with its FE model shown in b. The soft fin made of silicone rubber was moved by a vertically actuated rod, interacting with continuous hydrodynamic forces. c, Three different phases of deformation poses and their corresponding shape reconstructed in real-time as in d and Video 3, Warmer the color, higher the fiber strain induced along the fin contour. Note that the learning model training was conducted out of water beforehand. The unnoticeable deformation asymmetry can be reflected by its strains measured.