Movement Pattern and Efficiency of the Respiratory Pump of the Carp (Cyprinus Carpio L.)

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Abstract
A study of the function of the respiratory muscles is made by influencing the respiratory movements artificially (keeping jaw or opercula open or closed) and analysing the compensatory changes in muscle activity. The differential pressure curves during experiments with mouth and opercula open or closed confirm that the buccal and opercular pump are alternately effective. The respiratory efficiency of the pumps, in terms of both constancy of the water flow over the gills and volume output, decreases if the mouth opens before the transition from compression to expansion of the cavities (as is realized in the trout) and increases if it opens later. In the carp lower jaw abduction occurs at the same time as the transition. An electric analogue of the respiratory pumps has been constructed. It confirms the opinion that the respiratory pressure curves of fishes are generated by a double pump with in-phase cavity movements. Further, it demonstrates that the efficiency of the pumps is greater if lower jaw abduction is synchronous with the onset of cavity expansion (carp) than if it is earlier (trout). The efficiency, however, is shown to be maximal if the mouth opens slightly later.