Fig. 7. Swimming performance space. Hypothetical maps of anuran swimming performance were generated from forward dynamic simulations run across a range of kinematic input conditions. Since only two input parameters were varied (amplitudes of trigonometric functions describing translational and rotational foot displacement), a 3D hypothetical space could be systematically explored by mapping a single output (such as peak simulated swimming velocity) against each of the two independently varied inputs: peak rotational (x-axis) and peak translational (y-axis) foot velocity. The initial foot angle for each simulation in the performance space was derived such that the foot is 90 deg. to flow at mid stroke (t_0.5) to decouple the effects of foot translation vs rotation. The color scale (from 0 to 100%) shows two performance parameters: (A) peak stroke swimming velocity and (B) glide velocity (the velocity at the end of the power stroke). Contour lines inclined more horizontally indicate a higher dependence on translational velocity, whereas more vertical lines indicate a higher dependence on rotational velocity. Arrows in A and B show different examples in the parameter space: arrow I shows large foot translation and small rotation, whereas arrow II shows large rotation and small translation. The corresponding diagrams show the path of foot motion throughout each simulated power stroke. These examples illustrate how two contrasting stroke patterns can have identical peak velocities (50% maximum) yet different glide velocities (20% maximum vs 40% for examples I and II, respectively).