Meeting Abstract
72-2 Sunday, Jan. 6 08:15 – 08:30 The Big Gulp: Morphological Determinants and Scaling Relationships of Gape in Two Invasive Species of Large Snakes JAYNE, BC; BAMBERGER, AL*; Univ. Cincinnati; Univ. Cincinnati bruce.jayne@uc.edu https://www.artsci.uc.edu/departments/biology/byDeptMembers/faculty.html?eid=jaynebc&thecomp=uceprof
Snakes are a model system for studying gape-limited predators and how anatomy constrains and affects feeding performance and foraging. More than 3,500 extant snake species are phylogenetically diverse, consume a wide variety of prey, and have considerable ontogenetic and interspecific variation in size. However, the paucity of direct measurements of maximal gape and its morphological correlates have impeded understanding the apparent diversity of form and function of this system. To test the extent to which overall size predicted gape, we quantified the scaling relationships between maximal gape, overall size, and several cranial dimensions for a wide range of sizes for two large invasive species: 19 Burmese pythons (Henophidia, Pythonidae, Python molorus [Pm]) and 20 brown tree snakes (Caenophida, Colubridae, Boiga irregularis[Bi]). Our values of snout-vent length (SVL), mass, and maximal gape area ranged from 61-303 cm, 100-15890 g and 14-154 cm2 for Pm, and 40-184 cm, 8-1138 g and 0.8-23 cm2 for Bi, respectively. For similar values of SVL in common to both species (60 to 180 cm), values of Pm compared to Bi were: 6.4 to 4.2 times greater for mass, with 6.3 to 3.8 times larger for gape area, but just 1.7 to 1.6 times greater for skull length. The relative contributions to gape area from skull width, quadrate length, lower jaw length and the intermandibular ligament were 7%, 10%, 42%, and 41% for Pm, and 11%, 18%, 55%, and 17% for Bi, respectively. Rather than its large gape only resulting from larger overall size, P. molorus with similar body size to B. irregularis also had a larger skull, longer lower jaw bones and most importantly more distensible soft tissues of the chin and neck region, all of which enhanced gape.
