Fig. 6

Mechanism of hybrid fish spitting small fish. a Small fish (C. auratus). b A small piece muscle in the back of C. auratus. c-e The MicroCT image of pharyngeal bones of PP, SW and PS. f-h The detail image of grinding surface of pharyngeal bones of PP, SW and PS. i The average number of daily foraging (ANDF) for small fish or meat by these SP with a persistent spitting-fish behavior. j Compare the spitting rate (SR) of SP between foraging small fish and meat. k Compare the SR of SP between foraging S fish (small fish, 0.09 ± 0.01 g), M fish (medium fish, 0.26 ± 0.03 g), S meat (small meat, 0.10 ± 0.01 g), M meat (medium meat, 0.24 ± 0.01 g), B meat (big meat, 0.50 ± 0.05 g). l The relative maximum opening width between pharyngeal teeth (MOWPT). m The development degree of hook pharyngeal teeth (DDHPT). n The relative grinding surface area of pharyngeal teeth (GSAPH). The scale in a is 1 mm, in (b), the meat is 1 mm and the fish is 10 mm, in (c-e) is 0.5 mm, in (f-h) is 2 mm. The different ** above the boxes differ significantly at P < 0.01 based on Tukey test, the height give the mean, the thick lines give the medians, and whiskers indicate mean ± SE