Adaptations to diving in the harbor seal— gas exchange and ventilatory response to CO2

Abstract

Pulmonary gas exchange and the ventilatory response to CO₂ were measured in six female harbor seals, Phoca vitulina. Mean Pa co₂ (48 ± 6 mm Hg) is higher in the seal and mean Pa o₂ (88 ± 9 mm Hg) is lower than the corresponding value in man. The seal shows a depressed ventilatory response to CO₂ both in terms of slope and intercept of CO₂ response curves. The depressed respiratory center sensitivity to CO₂ presumably is an adaptative mechanism permitting prolonged diving in this species.