Hopkins Marine Station Student Paper

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Title: A study of intertidal porcelain crabs Petrolisthes cinctipes and their ability to regulate heart rate in relation to the effects of emersion.
Student Author(s): Tea, Kallin
Faculty Advisor(s): Somero, George
Pages: 21
Location: Final papers Biology 175H
Date: June 2003
Abstract: Intertidal organisms can spend a great deal of time out of water and must be physiologically adapted to tolerate terrestrial conditions. I hypothesized that one of the physiological adaptations made by intertidal organisms is reduction of metabolic rate during the low tide period. To test this hypothesis, I investigated the ability of the intertidal porcelain crab, Petrolisthes cinctipes, to regulate its heart rates during the transition from water to air. Heart beats were monitored by impedance electrodes at 100 C, 150 C, and 200 C during one hour of immersion followed by one hour of emersion. Heart rates were recorded using a PowerLab data acquisition system and were averaged for each 10 minute period of the experiment. Linear regression analysis was used to determine if heart rate varied with body size using crabs with carapace width ranging from 9mm to 16 mm. A significant increase in heart rate with body size was found. Heart rates were corrected for body size in comparisons of the effects of emersion. No significant effect of emersion was found (p-value of 0.079.) The temperature dependence (Q10 ) of heart rate also did not differ between immersion or emersion. In future studies, variables such as size should be more strenuously controlled for, and this may yield clearer results