Literaturdatenbank
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Sturbaum, B. A. (1972). Thermoregulation in the ornate box turtle, terrapene ornata. Unpublished thesis , University of New Mexico, Albuquerque.
Added by: Sarina Wunderlich (12 Dec 2010 20:43:15 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Sturbaum1972 View all bibliographic details  |
Categories: General Keywords: Emydidae, Physiologie = physiology, Schildkröten = turtles + tortoises, Terrapene, Terrapene ornata Creators: Sturbaum Publisher: University of New Mexico (Albuquerque) |
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| Abstract |
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Five series of experiments were conducted on eighteen Terrapene ornata to determine to what extent physiological responses are involved in the regulation of their body temperature during heat stress. Thermocouples were located on the surfaee of the carapaee and inserted into the abdominal and thoracie cavities and in the arm, leg, and neck appendages. Three silver-foil electrodes were applied on the carapaee to record heart rate. The turtles were heated in experimental chambers whieh provided for the eontrol of air temperature, air veloeity, and vapor pressure. Turtles also were heated and eooled in waterbaths at several temperatures for 30 min. During the first 10 min of waterbath experimentswhen the major eore temperature changes occur, there were no differenees in rates of heating and cooling. Oxygen eonsumption was measured at body temperatures from 23 to 40 C. The metabolie rate inereased as the body temperature increased wi th ''lide variations at most body temperatures cxamined. There was a sharp rise in the metabolie rates bet''leen 3S and 38 C and the metabolie rate at 40 C was more than three times that at 3S C. During exposure to high ambient temperatures the animals lost water by evaporation and urine exeretion sueh that initial weight losses were as high as 5.6% oE the body weight per hr. The onset of frothing represented an observable indieator of physiologieal thermoregulation. Turtles heated to frothing at an ambient temperature of 55 C and turtles exposed to temperatures of 43.3 to 51 C after preheating to a core temperature of 30 C, frothed at a core temperature of 36 C, a surface temperature of 39.6 C and a surface to core gradient of 3.6 C. No frothing was evident in another group of turtles maintained at 38 C even though the final core temperature ''las about 2 C above that at which frothing began in the other groups. After the onset of frothing, the core to surface and core to air gradients were established and the rate of he at exchange between animal and environment reachedequilibrium. Heart rate increased at higher ambient temperatures. Because of the wide range of heart rates at each temperature, it is difficult to determine the role heart rate plays in heat stress. The temperature gradients in animals which were cooling in 38 C or 30 C simulated field environments were dependent upon the temperature of the cooling environment. These animals had been preheated to 38 to 40 C before entering simulated field environments. At an ambient temperature of 30 C surface temperatures fell below those of the core, \'1hile at an ambient temperature of 38 C core temperatures fell below those of the surface indicating all heat was dissipated through the oral region. This study demonstrates that when behavioral means are inadequate, ornate box turtles have physiological means to keep body temperatures within tolerable limits for several hours.
Added by: Sarina Wunderlich |