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Importance of vision and olfaction in the red eared slider (Trachemys scripta elegans) during prey capture at differing turbidities and distances Amanda.

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Presentation on theme: "Importance of vision and olfaction in the red eared slider (Trachemys scripta elegans) during prey capture at differing turbidities and distances Amanda."— Presentation transcript:

1 Importance of vision and olfaction in the red eared slider (Trachemys scripta elegans) during prey capture at differing turbidities and distances Amanda Hoffman* and Dr. Jessica Nolan, York College of Pennsylvania Introduction Environmental Red eared sliders live in slightly marshy, shallow water with abundant vegetation. Increased sediment loads and turbidity over the past 2 decades due to increased urbanization, deforestation and agricultural land use could make foraging more difficult. Senses The turtle’s eye is like a chameleon as it can independently survey the environment. However, symmetrical fixation, in which both eyes share the same focal point, is observed during prey capture. The olfactory bulb is well developed, sensitive to a variety of scents and sensitive at low concentrations. Orientation toward prey In previous research, when the turtle was presented with a visual cue, the turtle would orient toward the cue. In contrast, when presented with a chemical cue, the turtle would orient itself in the direction of the current. Prey seeking behaviors observed were similar for both cues, only differing in the direction of the behavior (Constantino et al 2003). As distance increased from prey, prey captures also decreased, and turtles could not follow prey escape responses (Feder 1983). Compensation in rattlesnakes Strike time in rattlesnakes varied little between separate trials when vision was repressed and when olfaction was repressed. Compensation of the other sense likely occurred when one sense was missing (Kardong 1992). Turbidity In previous research on eastern painted turtles, no significant difference in time to prey capture was seen in 2-40 NTU water (Gross et al 2010). Perhaps compensation was occurring. Hypotheses: 1.Turbidity will not affect time to prey capture in the red eared slider. 2.Vision will be the most utilized sense in clear water, and olfaction will be the most utilized sense in turbid water. 3.Time to prey capture will increase as distance increases. Hypotheses: 1.Turbidity will not affect time to prey capture in the red eared slider. 2.Vision will be the most utilized sense in clear water, and olfaction will be the most utilized sense in turbid water. 3.Time to prey capture will increase as distance increases. Methods A 60 gallon tank with dimensions of 125 cm X 35 cm X 55 cm was used in which a current was established (Figure 1). Five turtles were used per trial. Trials proceeded as follows: Control Vision Impaired Olfaction Impaired Clear~40 NTU Perform at 30 cm and 120 cm from prey Time until prey capture Clear~40 NTU Perform at 30 cm and 120 cm from prey Time until prey capture Clear~40 NTU Perform at 30 cm and 120 cm from prey Time until prey capture Preference trials were also performed at 30 and 120 cm in which two differing prey items were presented to the turtle. Comparisons included orange vs. grey rosy red minnows, orange minnows vs. red unscented prey, grey minnows vs. red unscented prey and sardine scented rubber prey vs. non-scented rubber prey. Literature Cited Feder, M The relation of air breathing and locomotion to predation on tadpoles, Rana berlandiere, by turtles. Physiological Zoology 56: Constantino, M. A., and Salmon, M Role of chemical and visual cues in food recognition by leatherback posthatchings (Dermochelys coriacea L.) Zoology 106: Grosse, A. M., Sterrett, S. C. and Maerz, J. C Effects of turbidity on the foraging success of the eastern painted turtle. Copeia 2010: Henze, M. J., Schaffel, F., Wagner, H. J. and Ott, M Accommodation behavior during prey capture in the Vietnamese leaf turtle (Geomyda spengleri). Journal of Comparative Physiology 190: Kardong, K. V Proximate factors affecting guidance of the rattlesnake strike. Zoologishce Jahrbucher Anatomie 122: Singer, B. H., Kim, S. and Zochowski, M Binaral interaction and centrifugal input enhances spatial contrast in olfactory bulb activation. Journal of Compilation 25: Wachowiak, M., Cohen, L. B., and Zochowski, M. R Distributed and concentration invariant spatial representations of odorants by receptor neuron input to the turtle olfactory bulb. Journal of Neurophysiology 87: Results Conclusions: 1.Overall, T. scripta elegans should be only slightly affected by increased turbidity. 2.Vision seems to be the primary sense used in clear and turbid water. 3.There was no change in time to prey capture as distance increased. Once prey was seen, turtles quickly captured it. This is especially true for the longer distance. 4.Turtles preferred visually obvious prey objects in the preference trials, especially at 120 cm. Conclusions: 1.Overall, T. scripta elegans should be only slightly affected by increased turbidity. 2.Vision seems to be the primary sense used in clear and turbid water. 3.There was no change in time to prey capture as distance increased. Once prey was seen, turtles quickly captured it. This is especially true for the longer distance. 4.Turtles preferred visually obvious prey objects in the preference trials, especially at 120 cm. Figure 1. Diagram showing tank arrangement, taken from Grosse (2010). hop.de/homepage/fox-rage- 10/fox-rage-gummikoeder/fox- rage-chatter-tail.html


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