X-ray measurements of gill-arch movements in filter-feeding bream, Abramis brama (Cyprinidae).

The technique of X-ray cinematography was used to study pharyngeal movements in Abramis brama (L.). The theoretical and practical problems in X-ray cinematography of feeding fish are discussed, as well as criteria for the selection of images suited for detailed measurements. Respiration and filter-feeding on Daphnia pulex (length c. 1 mm) show different gill arch movement patterns in bream. Slits between gill-arches are kept smaller during filter-feeding. In addition, during filter-feeding, this inter-arch distance decreases considerably in a posterior direction. The hypothesis that particle retention occurs on the slits formed between adjacent gillarches and their gill-rakers is not supported by the present results.