Figure 1.
Body shape variation of fishes sampled in this study.
The examples show the range of fineness in both pectoral fin (MPF, top row) and body and caudal fin (BCF, bottom row) swimmers.
Figure 2.
Performance as a function of fineness for rigid bodies of revolution.
CD(f) (left panel) and modeled maximum-prolonged swimming speed (right panel) for laminar (A) and lower-end of turbulent (transitional) (B) flow. Drag coefficients are standardized using (Vol)2/3 as the reference area and computed for bodies of equal volume and speed, but differing Reynold's number (Re). Total (black line), skin friction (dotted red line) and pressure (thin blue line) components are illustrated. The elliptical figures above the plot are representative midline sections for finenesses of 2, 5, and 10 to show the relative length and depth of bodies of differing fineness but equal volume. The scale of the ordinate differs between (A) and (B) to emphasize the shape of the curve within each plot.
Table 1.
Relative cost of change in fineness.
Figure 3.
Maximum prolonged-swimming speed as a function of fineness in coral reef fishes.
(A) pectoral-fin (MPF) and (B) body and caudal fin (BCF) subsets. The values are adjusted using the residuals from the regression of Umax on M1/3 and AR (fin aspect ratio). The red line is the modeled Umax (eq. 2). The black lines are the quadratic fit of the adjusted Umax on fineness (f).
Table 2.
Correlations among predictor variables and between predictor variables and maximum prolonged swimming speed, Umax.
Figure 4.
Box-percentile plots of the distribution of model-averaged β coefficients.
The distribution is from 5000 bootstrap samples of maximum prolonged-swimming speed (logUmax) regressed on the predictor variables. For each bootstrapped pseudosample, the model-averaged β coefficients were computed from all retained (AICc≥min(AICc)+2) models in which the variable was included in the model. The outer, intermediate, and inner boxes represent the 95%, 75%, and 50% confidence intervals, respectively. The dashed line represents the median and the dot represents the observed value (Table 3). The scale of the ordinate is the same between (A) and (B) to emphasize the greater variance in the estimates in the BCF subset. Predictor variables are logM (body Mass), AR (propulsive fin aspect-ratio), f (body fineness ratio), and f2.
Figure 5.
Path model of effect of predictor variables on maximum prolonged-swimming speed (logUmax).
(A) pectoral fin (MPF) and (B) body and caudal fin (BCF) subset of coral reef fish species. Predictor variables are f (body fineness ratio), f2, AR (propulsive fin aspect-ratio), and logM (body mass). The linear and quadratic effects of f are combined to give the range of the effect from the fmin to fmax. The β coefficient (the number above the directed path) for each predictor is the model-averaged (standard partial regression) coefficients as described in the text. Correlations among predictors are given next to the bi-directional path.
Table 3.
Regression statistics of maximum prolonged-swimming speed on predictor variables.