The functional anatomy of the gills of the dogfish (Scyliorhinus canicula)

Abstract

Vascular casting techniques combined with scanning electron microscopy of fixed tissue have been used to describe the vascular anatomy of the gills of the dogfish (Scyliorhinus canicula). Two distinct blood pathways were revealed: a ‘respiratory’ blood pathway which conveys deoxygenated blood from the heart to the gas exchange surface of the gills and then carries oxygenated blood away to the systemic circulation, and a ‘non‐respiratory’ blood pathway which interconnects with the respiratory blood pathway and which diverts blood into the venous drainage from the gills.The physiological function of this complex circulation in the gills of elasmobranchs is discussed in terms of both the osmotic constraints upon the animal, and the possible control of blood flow.