Fig. 3. Ventilatory response of Cyprideis torosa to consecutive 3-day exposure periods at reference water P_O2=21 kPa, hypoxia, P_O2=3 kPa, and recovery P_O2=21 kPa. See text for details. (A,B) Typical ventilatory pattern (fR, ventilatory frequency) in two specimens of Cyprideis during 1 h observation periods at P_O2=21 kPa. Both activities are contrasted and characterized by alternations of ventilatory bursts and pauses. (C–E) Ventilatory activity per hour (C; min h^–1), burst number per hour (D; h^–1), mean ventilatory frequency within burst per minute (E; fR, min^–1) at P_O2=21 and 3 kPa (grey-shaded). Each data point (mean ± 1 S.D.) was obtained from a single podocopids, randomly chosen and analysed during the 1 h period. The ventilatory frequency within burst was also analysed during a 3-day recovery period (days 7 and 9) at P_O2=21 kPa (E). One symbol per individual, N=10 animals. No significant change was observed as a function of water P_O2 and time.