Conditioned Variation in Heart Rate During Static Breath-Holds in the Bottlenose Dolphin ().

Previous reports suggested the existence of direct somatic motor control over heart rate ( ) responses during diving in some marine mammals, as the result of a cognitive and/or learning process rather than being a reflexive response. This would be beneficial for O storage management, but would also allow ventilation-perfusion matching for selective gas exchange, where O and CO can be exchanged with minimal exchange of N. Such a mechanism explains how air breathing marine vertebrates avoid diving related gas bubble formation during repeated dives, and how stress could interrupt this mechanism and cause excessive N exchange.