Fig. 2. Fluke-beat frequency, f (Hz), as a function of length-specific swimming speed, U/L, where L is the body length and U is the swimming speed. Regression equation for all the cetacean data is: y=0.89x+0.59 (r²=0.8, N=267). Symbols indicate particular cetacean species: Tursiops truncatus (solid red circles), Pseudorca crassidens (open green squares), Orcinus orca (solid blue triangles), Globicephala melaena (blue crosses), Lagenorhynchus obliquidens (solid blue diamonds), Stenella frontalis (open brown diamonds) and Delphinapterus leucas (solid black triangles).