Respiratory characteristics of the hemoglobin-free fish Chaenocephalus aceratus

Abstract

1. 1. Studies on the Antarctic hemoglobin-free fish Chaenocephalus aceratus showed that the oxygen consumption was unusually low; the resting rate at 1°C averaged 0·020 ml O 2/g per hr. 2. 2. The rate was little affected by the oxygen content of the water at oxygen tensions above 40–50 mm Hg, indicating a high respiratory efficiency. 3. 3. Low blood lactic acid levels at rest (2–6 mg LA/100 ml) and after anoxic stress (24–36 mg LA/100 ml) indicate no unusually high anaerobic metabolism. 4. 4. The main respiratory compensation to the absence of hemoglobin appears to be an increase of blood volume (6·1–9·3 per cent w/w) and a high cutaneous respiration.