Figure 8.

(a) Ventral view of a bluegill turning to the right. The fin to the right is actively cupped into the flow, increasing the drag force. (b) Shapes of a model fin ray under three loading situations: 1, a concentrated normal point load (solid line, equation (5.1) with ϕ₀=0.01=0.01, Q=220, d=0.01, G=200, B=1 and s₀=2/3); 2, a uniform force per unit length (dashed line, equation (5.1) with ϕ₀=0.01, p=200, d=0.01, G=200 and B=1); 3, a ‘passive’ ray under the same uniform loading (dashed-dotted line), with a free base (∂_sϕ=0 at s=0). The difference between 2 and 3 shows the effect of changing the base shift ϕ₀ from its passive value.