5 Oxygen and Carbon Dioxide Transfer Across Fish Gills

Abstract

Publisher Summary This chapter discusses oxygen and carbon dioxide transfer across fish gills. The gills of fish are the major site, though not the only one, for oxygen and carbon dioxide transfer. The skin and fins may also serve in this capacity and many fish have evolved accessory air-breathing organs. These may be the modifications of the skin, buccal, pharyangeal, or gill surface, or they may be the regions of the gut or the swim bladder. In general, the gills of fish are the major pathway for oxygen and carbon dioxide transfer between the environment and the body tissues. The oxygen stores within the body, with the exception of that in the swim bladder, are small. Carbon dioxide stores in the body are large as compared with the rate of production. At resting rates of CO 2 production, it would take the animal several hours to accumulate the equivalent of the body CO 2 stores. Thus, minor changes in the magnitude of the CO 2 stores—for example, related to the acidification of the body tissues—can have a marked effect on CO 2 excretion across the gills.