Behavioral Adaptations in Turtles to Thermoregulation and Survival Paper
Thermoregulation is necessary for ectotherms to survive. One important mechanism for thermoregulation seen in turtles is the ability to migrate between land and water habitats. This mechanism was studied using I-button data loggers placed inside marshmallow peeps to record temperatures In two different microhabitats; one In a stream and the other on the bank adjacent to the stream. Five samples were placed in each microhabitat and temperature was recorded every minute for 20 minutes.
It was hypothesized that turtles In moving waters, such as streams, would exhibit lower body temperatures than those residing on banks alongside streams due to convection of the moving water. The results of this experiment Indicated a slgnlflcant dfference between body temperatures of the model turtles in each microhabitat. The temperatures of the samples in the stream were significantly lower than those of the samples on the bank.
These results indicate that the convection from the moving stream waters provide effective means for lowering body temperature in ectotherms nd, therefore, can be a critical behavioral adaptation for turtles Inhabltlng areas with warmer climates. Introduction Body temperature is a characteristic that is crucial to an organism’s survival. It affects numerous biological processes In organisms Including growth, metabolism, reproduction, and performance (Fitzgerald et al. 2006). In endothermic organisms, body temperature Is regulated by metabolism.
However, In ectothermic organisms, such as turtles, body temperature Is not maintained by metabolism; instead they must rely on the thermal environment surrounding them to regulate their body emperature. The mechanisms most responsible for body temperature changes In ectotherms include radiation, conduction, convection, and evaporation. Radiation is the gain or loss of heat energy from the sun. This mechanism Involves ectothermic organisms changing their body temperature by changing their position in relation to the sun. Convection is or the gain or loss of heat to or from an organism in moving fluid such as water or the wind.
Convection causes the body temperature of the ectotherm to equilibrate towards the temperature of the surrounding air or water. Conduction Is the gain or loss of heat to or from surfaces, and evaporation, or the loss of heat due to the conversion of liquid water on the body to gas (Thermal environments… [date unknown]). These mechanisms of thermoregulation can govern the behavior of ectotherms_ In order to regulate their body temperature, ectotherms must either utilize these mechanisms by finding habitats that expose them to these tors protection from these elements.
Semi-aquatic common snapping turtles in South Carolina, Chelydra serpentina, use behavioral adaptations such as basking in the sun to raise body temperature or swimming in streams, rivers, lakes, etc. o lower their body temperature (Bennett et al. 2005). In a body of moving water, such as a stream, convection from the movement of the water causes the turtle’s body temperature to equilibrate to the temperature of the water at a rapid rate. This is beneficial because it allows turtles to quickly lower their body temperature when necessary.
It can be a disadvantage for turtles because they may need to use water to find food or escape predators even when the water temperature is lower than their optimal temperature ranges. The rapid heat loss due to the convection of moving water will cause the urtle’s body temperature to quickly equilibrate toward the lower water temperature which may hinder the performance level of the turtle. Fortunately, according to laboratory studies, reptiles like the turtle are able to heat faster than they cool off so they can raise their body temperatures fairly rapidly by basking in the sunlight (Fitzgerald et al. 06).
These behavioral adaptations of turtles that allow them to migrate between microhabitats with different thermal environments quite easily, allow turtles to survive in more diverse climates, escape from certain predators, and orage for food in more locations. This ability to adapt is especially important today when we are facing issues such as global warming and seeing so many species become endangered or even extinct.
This experiment was done in order to observe the temperature differences between ectotherms, specifically the Chelydra serpentina turtles, in different microhabitats in order to see how much of an effect changing habitats has on a turtle’s body temperature. In order to do this, a stream was chosen for the first microhabitat and the bank along the sides of the stream for the second microhabitat. Both microhabitats were located in the shade in attempt to eliminate the effect of radiation on body temperature.
It was hypothesis was that the turtles in the stream would have a much lower body temperature than those on the bank due to convection. To model the turtles, I-buttons placed inside of marshmallow peeps were used. Materials and Methods The samples used to model the Chelydra serpentina were I-button data loggers each placed in the center of a marshmallow peep. The use of peeps made it easier to suspend the I-buttons in various locations. In order to keep the I-buttons inside each f the peeps, scissors were used to cut small circles in the center of each peep.
These I-buttons record the temperature every minute. These I-buttons were kept on ice in a thermos prior to beginning the experiment in order to create a thermal rise that facilitated locating the start of the experimental data when extracting it from the l- buttons. The habitat used for the experiment was a shaded area containing a stream and the bank surrounding the stream where turtles may inhabit in order to seek refuge from the hot temperatures of South Carolina at noon during the summer.
The reek was shallow, about a foot deep, and contained mostly sand with a few larger rocks on the bottom with a steady current. Both areas were completely shaded to eliminate radiation as a factor. A total of ten peeps were used and five were placed in different areas in a stream, while the other five were placed in various areas along the bank of the stream. Strings were tied to the samples placed in the stream and samples submerged and to keep them from being carried away with the current.
The samples were left in their locations for twenty minutes in order to give the I-buttons ample time to equilibrate to the environment. This data was then extracted from the I-buttons and organized by temperature per minute for each sample in separate excel tables for each microhabitat. The average, standard deviation, confidence interval, and upper and lower confidence intervals for the temperature each minute was calculated using excel for each of the microhabitats. The temperatures for the last minute, the 20th minute, for each sample were organized into another table separated by microhabitat.