Effects of ingesting large prey on the kinematics of rectilinear locomotion in Boa constrictor

Large and stout snakes commonly consume large prey and use rectilinear
crawling, yet, whether body wall distention after feeding impairs
rectilinear locomotion is poorly understood. After eating large prey
(30-37% body mass), all Boa constrictor tested could perform rectilinear
locomotion in the region with the food bolus despite a greatly increased
distance between the ribs and the ventral skin that likely lengthens
muscles relevant to propulsion. Unexpectedly, out of eleven kinematic
variables, only two changed significantly (P<0.05) after feeding:
cyclic changes in snake height increased by more than 1.5x and the
longitudinal movements of ventral skin relative to the skeleton decreased
by more than 25%. Additionally, cyclic changes in snake width suggest that
the ribs are active and mobile during rectilinear locomotion particularly
in fed snakes, but also in unfed snakes. These kinematic changes suggest
that rectilinear actuators reorient more vertically and undergo smaller
longitudinal excursions following large prey ingestion, both of which
likely act to reduce elongation of these muscles that may otherwise
experience substantial strain.