Heart rate was chronically monitored (Figs. 1, 3) in two species of the marine gastropod Aplysia. The warm water A. brasiliana have an average basal heart rate in water of 33 min-1, whereas the cold water A. californica's heart rate is 20.6 min-1. The heart rate in both species shows a strong temperature dependence and the difference in basal heart rate is negligible when measured at the same temperature (Fig. 2). Both species show a consistent bradycardia when exposed to air (Fig. 4):A. brasiliana showed a 43% average decrease in air, whereas A. californica showed only a 16.5% decrease. Removal of the abdominal ganglion produced no significant decrease in heart rate in either species, nor did it reduce the bradycardial response to air exposure in A. californica (Fig. 8). However, it significantly reduced, but did not abolish, the bradycardia in A. brasiliana (Figs. 5, 6, 7). We conclude that the bradycardia has a significant central component in A. brasiliana, but is peripherally mediated in A. californica. The bradycardial response to air exposure may be analogous to the diving response in air breathing vertebrates.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Animal Science and Zoology