 It is likely that the reversed temperature effect on oxygen binding was developed to ensure adequate unloading of oxygen at the heart and liver, especially in colder waters when the difference in temperature between these organs and the swimming muscle is the greatest.Since southern bluefin tunas must constantly be swimming to drive water over the gills and provide their bodies with oxygen, there is a requirement for their metabolic rate to constantly be high.Unlike other organisms, the southern bluefin tuna cannot expend more energy to produce heat in cold temperatures, while slowing down metabolism to cool down in high temperature waters and maintain a homeostatic temperature.