HEART-RATE AND BEHAVIORAL-PATTERNS OF MEGALOBULIMUS-SANCTIPAULI (MOLLUSCA, GASTROPODA, PULMONATA)

Adult specimens (N = 20) of the pulmonate land snail Megalobulinus sanctipauli were observed systematically in the laboratory and four behavioral patterns reflecting different degrees of activity are described. The changes in heart rate associated with different behavioral patterns were monitored using three silver chloride electrodes chronically implanted in the visceral mass of the animals (N = 13). Continuous heart rate recordings were performed at room temperature (25-degrees-C) with a Nihon Kohden polygraph model RM-45. Analysis of the results by the Multiple Comparisons Test based on Friedman rank sums revealed significant differences in heart rate, reported as median, between the following behaviors: retracted into the shell and locomotion, 25 vs 35 (P < 0.008), retracted and eating, 25 vs 38 (P < 0.008), still with local activity and eating, 33 vs 38 (P = 0.021). These results indicate that different levels of activity have different effects on the cardiac function of Megalobulimus sanctipauli. The lowest heart rate was associated with the animal retracted into the shell. The highest rates were related to locomotion and feeding behaviors.