Gill Dimensions in Pelagic Elasmobranch Fishes

The warm-bodied great white shark, Atlantic shortfin mako, and common thresher shark exhibit larger total gill surface areas than do ectothermic blue sharks, sandbar sharks, dusky sharks, or scalloped hammerhead sharks. The means by which the three former species have achieved this greater gill surface area differ. Total filament length per given body size in the great white shark is greater than in any other species of elasmobranch examined. In contrast, the Atlantic shortfin mako and common thresher sharks appear to rely upon larger secondary lamellae area as a means of increasing total gill surface area. None of the three species exhibit spacing of secondary lamellae which differ significantly from the arrangements found in the ectothermic species of elasmobranchs. Larger gill surface areas per unit body weight allow for greater volumes of water to be used effectively in the transference of oxygen to the blood, thereby increasing the total amounts of oxygen available to support the high energy physiology of the warm-bodied species.