Fig. 6. (A) Individual responses (N=11) in appendage beating rate (fA; solid and broken lines) to decreasing ambient oxygen tensions at high food concentration (10⁵ algal cells ml^-1). The profiles were shifted vertically for clarity. Eight of 11 animals showed a hyperventilatory response (solid lines). The dotted lines indicate the two reference points, the initial normoxic level at 21 kPa and the hypoxic level of 3 kPa, which were used to assess the hypoxia-induced changes in fA. (B) Magnitude of hypoxia-induced changes in fA in relation to the initial fA prevailing before the start of the hypoxic exposure. The dotted line demarcates positive (open circles) from negative responses (filled circles).