Counter-Current Vascular Heat Exchange in the Fins of Whales

Abstract

Vascular supply to the fins and flukes of 2 spp. of porpoises. Lagenorhynchus acutus and Tursiops truncatus, is described. All major arteries entering the fins and flukes are surrounded by a trabeculate venous channel. Arteries drain into these, but also into superficial simple veins. This concentric arrangement of the artery within the venous channel is interpreted as a heat-conserving counter-current exchange system. Heat regulatory aspects of the 2 venous systems are discussed.