Fig. 5. Changes in (A) heart rate (beats min^-1), (B) stroke volume (ml beat^-1), (C) cardiac output (ml min^-1) and (D) ventilation rate of the branchial chambers (beats min^-1) of eight Cancer magister. Crabs were monitored during a 3 h control period in normoxia, before hypoxic conditions of 3.2 kPa were initiated for 3 h. Crabs were then fed and monitored for a further 6 h in hypoxia after which normoxic conditions were restored for an additional 6 h. Values ARE means ± S.E.M. In some cases standard errors were very small and do not show clearly on the figure.