Relative size and myocardial structure of the heart of an Antarctic fish devoid of haemoglobin and myoglobin, Channichthys rhinoceratus

The relative size and the ultrastructure of the heart ventricle of a haemoglobinless and myoglobinless teleost, Channichthys rhinoceratus, has been investigated. It is two to three times larger than that of a red-blooded species which also lives in the Kerguelen archipelago, Notothenia magellanica. At first sight, electron micrographs of the myocardial cell do not reveal peculiar features related to the absence of respiratory pigments. A mitochondrial compartment amounting to 18% volume fractions indicates a fairly high aerobic metabolism.