Meeting Abstract

P3.78  Wednesday, Jan. 6  A Mechanical Comparison of Shell Morphology in Two Subspecies of Chrysemys picta GOODFRIEND, Amy C.*; STAYTON, C. Tristan; Bucknell University; Bucknell University acg010@bucknell.edu

The construction of a turtle’s shell has been hypothesized to affect its performance under various loading conditions. The arrangement of bony plates in the carapace of the turtle shell can vary from species to species. The well-known painted turtle (Chrysemys picta), is divided into four subspecies; the two of interest in this study are the eastern painted turtle (C. p. picta) that has aligned scutes on its carapace, and the midland painted turtle (C. p marginata) that has alternating scutes. Hybrid individuals have shell constructions intermediate to the two subspecies. Turtle shells were photographed in dorsal, lateral, and ventral views and landmark coordinates were placed on the carapace and plastron. Finite element models were constructed using those date, with sutures and bone assigned different material properties. Eighteen load cases were analyzed – the resulting data were used to compare individuals of the different subspecies. C. p. marginata shells were on average stronger than those of C. p. picta and the hybrid individuals fell in between the two. It has been hypothesized that the different shell constructions are a result of different environmental conditions during the incubation period. C. p. picta may not have been subjected to as severe selective pressures for shell strength as C. p. marginata due to the smaller size of predators found within its native range.