Temperature manipulation induces ecdysis in lab-held rattlesnakes

Carnes-Mason, Maxwell D. 

carnesmm@oregonstate.edu    

Department of Fisheries, Wildlife, and Conservation Sciences                                                           

Oregon State University                                                                                                                              

Corvallis, Oregon USA

Beaupre, Steven J.                                                                                                                                            

Dean of the Graduate School                                                                                                                       

Arkansas State University                                                                                                                            

Jonesboro, Arkansas USA                                                                                                                                                                                                                                                         

Ecdysis is a defining feature of all squamate reptiles, occurring at least annually in snakes.  Shedding occurs at irregular and unpredictable intervals, inhibiting studies of the importance of ecdysis to life history. To date, limited information on the endocrine mechanisms controlling ecdysis has been used to induce sheds via endocrine gland removal. However, whole-gland removal is often lethal, limiting the scope of any conclusions drawn from these studies. We used data from the literature and reports of the natural timing of shed events in rattlesnakes to design a novel, non-invasive method for inducing ecdysis in the laboratory. Temperature manipulations following simulated brumation periods were used to induce ecdysis. Temperature trials were successful in inducing ecdysis in 63% of treated animals (28 of 44).  Efficacy of the induction of ecdysis induction via temperature manipulation was related to body condition and time since previous shed cycle (with high body condition animals that had not shed in the 3 months prior being most likely to shed). The timing of ecdysis (Immediate or Delayed) relative to temperature manipulation was related to days since last shed but not body condition, with those who had not shed > 5 months prior to manipulations being most likely to shed immediately after warming from brumation temperatures (10⁰C). Temperature manipulation shows potential for use in the lab-based induction and study of ecdysis, particularly in high body condition animals that have not shed in several months. A reliable method to induce ecdysis in the laboratory provides novel opportunity to investigate the physiological and ecological implications of an under-studied but ubiquitous function in squamates.