 Instead, the southern bluefin tuna seems to implement a system that regulates how actively the rete mirable system heats the tissues.Experiments involving the southern bluefin tuna have led researchers to believe that this species of tuna has developed a shunting system.When the southern bluefin tuna experiences cold temperatures, more blood is directed to the rete vascular system, heating muscle tissue, while in warm temperatures, blood is shunted to the venous and arterial systems, reducing the heat in the muscle tissues.