Figure 1.

Key features in individual fin rays (adapted from [15]). (a) Fish fins combine high morphing efficiency and high stiffness from external loads, two properties that are mutually exclusive in engineering morphing materials. (b) An individual ray from a fish fin harvested from Atlantic salmon (Salmo salar) is ‘morphed’ by applying push/pull forces manually. (c) Micro-CT scans of a caudal fin ray from Atlantic salmon in rest position and actuated position. The hemitrichs ‘glide’ on one another, which induces flexural deformations.(d) Fish can change the shape and effective surface of their fins from actuation by base muscles (adapted from [16]). (e) Cross-section of a fin showing the bony rays and surrounding compliant tissues. (f) Schematic of this mechanism.