Caudal pseudoautotomy in three Sri Lankan species of snakes (Natricidae and Viperidae)

Abstract

S elf-amputation of expendable body parts as a defensive strategy has evolved multiple times independently in the animal kingdom, and has been observed among both vertebrates (mammals, salamanders, non-serpentine lizards) and invertebrates (echinoderms and crustaceans) (Clause and Capaldi 2006). However, caudal autotomy, the ability to voluntarily detach the tail in response to an encounter with a predator has been frequently observed among salamanders and lizards (Pough et al. 2016). Its frequent expression across multiple herpetofaunal taxa suggests that caudal autotomy is a successful behavioral response that substantially elevates the survival rate of potential prey (Clause and Capaldi 2006). Among lizards, this behavior has been observed in 13 of 20 lizard families (Downes and Shine 2001) and its evolutionary history is traceable to Early-Permian captorhinids. By detaching the tail from the body, lizards can escape a predator's grasp while the severed tail continues to spontaneously and vigorously writhe, attracting the predator's attention away from the lizard (Edmunds 1974;Bateman and Fleming 2009).However, caudal pseudoautotomy, intervertebral tail detachment in response to mechanical resistance without tail regeneration, is infrequently observed among snakes (Ananjeva and Orlov 1994;Dutta et al. 2022), with this behavior mostly documented among African colubrids (Broadley 1987;Akani et al. 2002). Thus far, caudal pseudoautotomy has been recorded in only a few snake genera (Amphiesma, Coluber,