Figure 4

A) Change of arterial and venous oxygen saturation and B) venous oxygen release by octopod haemocyanin with temperature. Data refer to an arterial PO₂ of 13 kPa and to venous PO₂ for a resting (4 kPa) and exercised (1 kPa) octopus. Arterial and venous PO₂ were assumed to be constant across temperatures and not determined for the analysed octopod species and instead taken from Octopus vulgaris [50,51]. Venous pH values were alpha-stat adjusted for each temperature and arterial pH assumed to be 0.11 pH units higher than venous pH [50]. Venous oxygen release including the contribution by dissolved oxygen is indicated by dashed lines. The ten degree temperature windows cover habitat temperatures for each species except for Pareledone charcoti.