Figure 8.

Additional release of oxygen by haemocyanin relieves the circulation system of Pareledone charcoti at 10°C. Oxygen that remained bound to haemocyanin at 0°C (blue) was largely liberated at 10°C (red), and thereby reduces the need for increased blood circulation (i.e. expressed as number of times to circulate the whole blood volume per second, 5.2% vs. 110.4% increase in circulation) to match an increased oxygen demand at 10°C. Oxygen supply rates (O₂ release from haemocyanin between 13 and 4 kPa PO₂, solid lines) match oxygen consumption rates of Pareledone charcoti (mean MO₂ ± SD, 0.63 mmol O₂ kg⁻¹ (wet mass) h⁻¹ ± 0.12, at 0°C, vertical dashed lines, taken from [7]) at the intersections of both rates at 0°C or 10°C (values indicated on x axis). Oxygen supply comprises the oxygen transported by haemocyanin only without contributions by dissolved oxygen or oxygen absorbed via the skin. The MO₂ at 10°C was interpolated assuming a Q₁₀ of 2.12 (average Q₁₀ for Octopoda taken from [46-48]. The blood volume was assumed to be 5.2% (v/w) based on average literature values from Octopus vulgaris and Enteroctopus dofleini [78,79].