HEAT CONSERVATION IN TUNA FISH MUSCLE

Abstract

Tuna fish maintain their body temperature above ambient water temperature. The countercurrent flow of blood and water in the gills of fishes ensures that the blood comes to water temperature, and in most fish metabolic heat is thus dissipated. In tuna a highly developed countercurrent heat exchange system located in the vascular system of the muscle provides a thermal barrier which prevents heat from being carried off by the blood and lost through the gills. The heat exchange system also lowers the thermal gradient between the surface of the body and the water and reduces heat loss through surface cooling.