3D bite modeling and feeding mechanics of the largest living amphibian, the Chinese giant salamander Andrias davidianus (Amphibia:Urodela).

Josep Fortuny,Montserrat Sanchez,Jordi Marcé-Nogué,Egon Heiss,Àngel Galobart,Lluis Gil

doi:10.1371/journal.pone.0121885

Abstract

Biting is an integral feature of the feeding mechanism for aquatic and terrestrial salamanders to capture, fix or immobilize elusive or struggling prey. However, little information is available on how it works and the functional implications of this biting system in amphibians although such approaches might be essential to understand feeding systems performed by early tetrapods. Herein, the skull biomechanics of the Chinese giant salamander, Andrias davidianus is investigated using 3D finite element analysis. The results reveal that the prey contact position is crucial for the structural performance of the skull, which is probably related to the lack of a bony bridge between the posterior end of the maxilla and the anterior quadrato-squamosal region. Giant salamanders perform asymmetrical strikes. These strikes are unusual and specialized behavior but might indeed be beneficial in such sit-and-wait or ambush-predators to capture laterally approaching prey. However, once captured by an asymmetrical strike, large, elusive and struggling prey have to be brought to the anterior jaw region to be subdued by a strong bite. Given their basal position within extant salamanders and their “conservative” morphology, cryptobranchids may be useful models to reconstruct the feeding ecology and biomechanics of different members of early tetrapods and amphibians, with similar osteological and myological constraints.

Highlights

The uptake of food is vital for all animal life, and feeding adaptations suited to specific environments in order to exploit food sources were essential for vertebrate evolution [1,2]
Limited information is available in the literature about how it works and the functional implications of biting system in amphibians in general and in salamanders in particular are still poorly understood such knowledge might be essential to understand feeding systems performed by early tetrapods
Suture morphology is described on the basis of the CT scans with the aim to understand its mechanical significance and the potential intracranial flexibility of the skulls

Summary

Introduction

The uptake of food is vital for all animal life, and feeding adaptations suited to specific environments in order to exploit food sources were essential for vertebrate evolution [1,2]. Aquatic salamanders typically capture their prey by suction feeding, where a fast oropharyngeal volume expansion pulls prey and surrounding water into the gaping mouth [3,4,5,6,7,8]. Analogous to aquatic prey capture, the jaws and dentition are used for fixing and immobilizing the prey. The biting apparatus is essential for successful prey capture and processing both in aquatic and terrestrial strikes and the prey spectrum is constrained by the functional architecture of the jaw-skull system, which has to cope with different levels of stress [5,11]. Former studies have shown that biomechanical approaches involving the analyses of movements and forces, combined with theoretical models, can help explain the divergence of the feeding systems in animals occupying different ecological niches [12]

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