THE PATTERN AND INFLUENTIAL FACTORS OF AQUATIC PHARYNGEAL MOVEMENTS OF TRIONYX-SINENSIS

1. The pharyngeal movements of Trionyx sinensis during submersion wher e recorded with physiological instruments. 2. Anoxia or hypercapnia ca used a marked increase in breathing rate of tested turtles during volu ntary diving, and in anoxia there was a significant increase in the fr equency of aquatic pharyngeal movements while hypercapnia had a slight or no effect on the frequency of these movements. 3. During voluntary diving when turtles could easily extend their heads out of water to b reathe air, the frequency of rhythmic pharyngeal movements was lower; but during forced submersion, the frequency was higher and the movemen ts were continuous. 4. The frequency increased more rapidly and greatl y when turtles were in forced submersion than when they dived freely a nd could easily surface to breathe in N2. 5. The frequency of pharynge al movements of T. sinensis during diving in an aquarium with water de pth of 30 or 45 cm was markedly higher than that at a water depth of 1 5 cm. Disturbing stimuli also influenced the aquatic rhythmic pharynge al movements of T. sinensis.