Preliminary observations on the heart of the haemoglobinless Antarctic fish Champsocephalus gunnari, Lönnberg.

The heart of the haemoglobinless and myoglobinless "icefish" Champsocephalus gunnari shows interesting morphometric and histological features. The relative heart weight in two animals (body weights 479.2 and 481.0) was significantly greater than in other sea-water teleosts and corresponds to values found in small mammals (with the exception of tuna). The histological features of both the ventricular myocardium and the bulbus arteriosus as well as the unique appearance of the parietal pericardium indicate important adaptations in the circulatory functions of this animal.