 The octopus' respiratory pigment, hemocyanin, also assists in increasing oxygen uptake.Octopuses can maintain a constant oxygen uptake even when oxygen concentrations in the water decrease to around 3.5 kPa or 31.6% saturation (standard deviation 8.3%).If oxygen saturation in sea water drops to about 1–10% it can be fatal for Octopus vulgaris depending on the weight of the animal and the water temperature.