Sherri Ann Emer

Burmese pythons (Python molurus bivitattus) use a unique infrared (IR) targeting system to acquire prey, avoid predators and seek thermoregulatory sites through detection of IR energy in the environment. Previous studies of sensitivity of the python IR system that relied on analysis of complex, natural behaviors lacked robust, reliable responses in animals habituated to experiments, and in vitro electrophysiological study failed to test behavioral function of the implicated protein thermoreceptor, TRPA1. The present study used conditioned discrimination procedures to analyze behavioral sensitivity and signal transduction in the python IR system. Pythons trained to behaviorally discriminate thermal stimuli averaged 70% correct choices, but failed to make correct choices when pit organs were physically occluded with IR-blocking material. The pythons exhibited greater sensitivity to thermal stimuli than previously reported, evident by correct choices that exceeded chance in response to a 14 × 10−6 W cm−2 irradiance contrast, or 0.5 °C thermal differential. Finally, in a test of the behavioral role of the putative thermoreceptor protein TRPA1, despite pit organ treatment with a TRPA1 inhibitor, python performance exceeded chance and was similar to baseline discrimination and control trials. Collectively, the results suggest that the IR system is a high sensitivity, broad-spectrum thermosensor that may operate through different and/or multiple thermoreceptive proteins with overlapping spectral response profiles. The findings reported here provide a better understanding of the relationship between the brain, behavior and environment in driving survival and ecological success of the Burmese python, especially as an invasive megapredator in the southern United States.

Large pythons and boas comprise a group of animals whose anatomy and physiology are very different from traditional mammalian, avian and other reptilian models typically used in operant conditioning. In the current study, investigators used a modified shaping procedure involving successive approximations to train wild Burmese pythons (Python molurus bivitattus) to approach and depress an illuminated push button in order to gain access to a food reward. Results show that these large, wild snakes can be trained to accept extremely small food items, associate a stimulus with such rewards via operant conditioning and perform a contingent operant response to gain access to a food reward. The shaping procedure produced robust responses and provides a mechanism for investigating complex behavioral phenomena in massive snakes that are rarely studied in learning research.

Excerpt: The native distribution of Trachemys scripta elegans, the redeared slider, is limited to the Mississippi Valley from Illinois to the Gulf of Mexico (Ernst et al. 1994). For decades, T. s. elegans has been the most popular turtle in the pet trade worldwide. Furthermore, large numbers of adults have been shipped around the world as laboratory animals. From these sources, T. scripta has been introduced into many areas outside of its native range. Introduced populations have been reported worldwide in Japan, Germany, Israel, South Africa, and the Mariana Islands (Ernst et al. 1994), and in the U.S. in Michigan, Arizona, Hawaii, Pennsylvania, New Jersey, Washington D.C., and Virginia (Conant 1975; Ernst et al. 1994; Mitchell 1994). In Florida, introduced populations have been reported in Dade Co. (Wilson and Porras 1983), Orange Co. (Bancroft et al. 1983), and in Pinellas Co. at Coquina Key, Gulfport, Sawgrass Lake Park, Boyd Hill Park, and Eckerd College (Hutchison 1992; P. Meylan, pers. comm.; G. Heinrich, pers. comm.).