The importance of the diaphragmaticus muscle to dive time in the American alligator


Meeting Abstract

P2.33  Friday, Jan. 4  The importance of the diaphragmaticus muscle to dive time in the American alligator. URIONA, T J; LYON, M L*; FARMER, C G; University of Utah; University of Utah; University of Utah kitty329m@gmail.com

We studied the effects of transection of the crocodilian diaphragmaticus on dive times and found that this muscle appears to help the animals resolve the discordant demands of diving with air in the lungs, that is, the problem of carry an oxygen reservoir in the lung while at the same time dealing with the effects of this air on buoyancy, pitch, and roll. Like the mammalian diaphragm, the crocodilian diaphragmaticus assists costal inspiration, but contraction of the crocodilian diaphragmaticus muscle shifts the lungs caudad, and in this way the muscle may also play a role in aquatic locomotion. Dive times were measured at 22 and 28�C in the transected animals and in a sham operated group (control) when fasting and after having eaten either a positively buoyant meal or a negatively buoyant meal, and when carrying a weight on either the head or the tail. The observer was blind to the identity of the animals. By manipulating metabolism, buoyancy, and center of mass, we were able to study the complex interaction between metabolic and locomotor demands. We found a significant decrease in the average dive time in the transected group compared to the controls at 22�C but not at 28�C in the fasting state. No significant difference in dive times were found between the groups after having eaten a buoyant meal, but significantly longer dive times were found in controls than the transected group in the fasted state. Preliminary results for the negatively buoyant meal indicate the controls have the longer dive times in both the fasted and fed state.

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