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Missouri Southern State University logo

Lexis Mader

Biology Major
Physical and Biological Sciences Category


My name is Lexis Mader. I am a senior with a biology field/conservation major. I want to go to graduate school in museum preparation. I have worked with Dr. Penning on various projects such as field research at Kellogg Lake, snake research, and turtle research. 


Alligator Snapping Turtles (Macrochelys temminckii) are listed by the IUCN (International Union for Conservation of Nature) as a vulnerable species in need of protection. They are slow-growing, long-lived turtles and are the largest freshwater turtle in the United States. They are also well known for their ability to bite with damagingly high forces during both predation and defensive encounters. These bites can be elicited in both winter and summer months if captured. However, being ectothermic, their body temperature is highly reliant on external heat sources. Therefore, changes in body temperature are likely to impact some, or all, of their defensive abilities. Using high-speed video cameras, motion capture software, and force transducers, we measured the bite force and lunge speeds from a group of captive M. temminkii held at 5, 15, and 25°C to test for any potential impacts of body temperature on defensive performance. 


Poster Presentation