 The southern bluefin tuna seems to increase blood flow to the stomach at times of increased digestion, by increasing the diameter of blood vessels flowing to the stomach, allowing more warm blood to reach the organ at a quicker rate.The eyes and the brain of the southern bluefin tuna are a common area of research involving the thermoregulatory systems of this species.Both the eyes and the brain maintain a remarkably high temperature when compared to the surrounding water environment, often higher than the temperature of the water.