The pattern and influential factors of aquatic pharyngeal movements of Trionyx sinensis

Abstract

1. 1. The pharyngeal movements of Trionyx sinensis during submersion where recorded with physiological instruments. 2. 2. Anoxia or hypercapnia caused a marked increase in breathing rate of tested turtles during voluntary diving, and in anoxia there was a significant increase in the frequency of aquatic pharyngeal movements while hypercapnia had a slight or no effect on the frequency of these movements. 3. 3. During voluntary diving when turtles could easily extend their heads out of water to breathe air, the frequency of rhythmic pharyngeal movements was lower; but during forced submersion, the frequency was higher and the movements were continuous. 4. 4. The frequency increased more rapidly and greatly when turtles were in forced submersion than when they dived freely and could easily surface to breathe in N 2. 5. 5. The frequency of pharyngeal movements of T. sinensis during diving in an aquarium with water depth of 30 or 45 cm was markedly higher than that at a water depth of 15 cm. Disturbing stimuli also influenced the aquatic rhythmic pharyngeal movements of T. sinensis.