Meeting Abstract

89.2  Friday, Jan. 6  Biomechanical properties of the intermandibulo-cervical integument of alligators: Implications for a more accurate understanding of the alligator feeding mechanism DUBANSKY, Brooke H.*; HOMBERGER, Dominique G.; Louisiana State Univ., Baton Rouge; Louisiana State Univ., Baton Rouge

Alligators do not use their tongues to transport food from their oral cavity into their pharynx and have, therefore, been thought to swallow prey items whole or in large pieces by using a cranio-inertial feeding mechanism, which would require the intermandibulo-cervical integument to be expandable circumferentially to let large prey items pass through the throat. The alligator integument comprises rigid, non-imbricating and hard-cornified scales that are separated by flexible and often expandable interscale skin. The interscale skin between rows of scales is folded in the resting position; it unfolds and expands upon being stretched and is returned to its folded resting position by the resilience of elastic fibers. The intermandibular integument is expandable in all directions (except where it forms a firm plate of tightly arranged scales underlying the hyoid), which allows the manipulation of large food items in the oral cavity. The cervical integument expands only along the longitudinal axis of the neck through the unfolding of the interscale skin between circumferential rows of scales, whose caudal edges slightly overlap the cranial edges of the following scale row in the resting position. Hence, the cervical integument cannot expand circumferentially. Therefore, while alligators use a cranio-inertial feeding mechanism that is generally correlated with swallowing large prey items, our functional-anatomical data reveal that the cervical integument of alligators actually limits the size of food items that can pass through the throat and, thereby, prevents swallowing food items that are too large to pass through the narrow thoracic inlet.