Fig. 3. Three-dimensional representation of the model used for calculation of power requirement of suction feeding in C. gariepinus. The model consists of 201 serially arranged hollow elliptical cylinders (left). Each cylinder consists of an external ellipse bordering the fish's head and an internal ellipse bordering the buccal cavity (right). Movement of the centres of mass (red and green dots) of 40 subdivisions of the modelled head volume (red and green segments) with respect to a fixed frame of reference (XYZ) was computed during the expansive phase for each cylinder. The 16 segments that approximately correspond to the neurocranium are indicated in red. Note that depth, d, is exaggerated for clarity. See text for further explanation and definition of symbols.