Abstract
In addition to biting, it has been speculated that the forces resulting from pulling on food items may also contribute to feeding success in carnivorous vertebrates. We present an in vivo analysis of both bite and pulling forces in Varanus komodoensis, the Komodo dragon, to determine how they contribute to feeding behavior. Observations of cranial modeling and behavior suggest that V. komodoensis feeds using bite force supplemented by pulling in the caudal/ventrocaudal direction. We tested these observations using force gauges/transducers to measure biting and pulling forces. Maximum bite force correlates with both body mass and total body length, likely due to increased muscle mass. Individuals showed consistent behaviors when biting, including the typical medial-caudal head rotation. Pull force correlates best with total body length, longer limbs and larger postcranial motions. None of these forces correlated well with head dimensions. When pulling, V. komodoensis use neck and limb movements that are associated with increased caudal and ventral oriented force. Measured bite force in Varanus komodoensis is similar to several previous estimations based on 3D models, but is low for its body mass relative to other vertebrates. Pull force, especially in the ventrocaudal direction, would allow individuals to hunt and deflesh with high success without the need of strong jaw adductors. In future studies, pull forces need to be considered for a complete understanding of vertebrate carnivore feeding dynamics.
Highlights
The force applied to food items by vertebrates is strongly associated with morphology, behavior, and fundamental ecological niche
Bite force When V. komodoensis bit the transducer, it remained engaged until the meat was removed
Conclusions and future research The disproportionately large forces resulting from pulling in the ventrocaudal direction provide an explanation as to how a carnivorous vertebrate can successfully secure and modify prey with a relatively low jaw adductor generated bite force
Summary
The force applied to food items by vertebrates is strongly associated with morphology, behavior, and fundamental ecological niche. Less frequently considered is the role of pulling on the prey, presumably facilitated mostly by postcranial musculature, on feeding success. Muscles extrinsic to the jaw apparatus may play an important role in amplifying the forces applied to food items for many taxa [4,6]. Several studies have directly observed feeding behaviors that incorporate postcranial muscles and some have modeled the forces [20,21]. Modeling approaches are useful in a comparative context they can considerably misrepresent actual forces [4,22]. These forces are rarely measured in vivo
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