Chuck Bednar for redOrbit.com – @BednarChuck
The world’s largest living amphibian, the Chinese giant salamander (Andrias davidianus), is capable of feeding not only on prey located directly in from of it, but also on creatures which approach from the side, thanks to a newly-discovered quick-strike technique.
The mechanism was discovered by Josep Fortuny from Institut Català de Paleontologia in Spain and his colleagues using three-dimensional modeling to explain the feeding mechanisms of the endangered creature. The findings were published Wednesday in the journal PLOS One.
Creating a 3D model of the salamander’s bite
The Chinese giant salamander uses a sit-and-wait strategy combined with his sudden bite to dine on approaching worms, crustaceans, fish, amphibians and small mammals. Now, thanks to a new 3D model, Fortuny’s team explains in detail the feeding mechanisms utilized by the creature.
They modeled the biomechanics of its bite using 3D CT-scan images of the giant salamander’s skulls, then applying a numerical technique known as finite element analysis to investigate the distribution of the forces within the creature’s skull. That analysis revealed that, in addition to feeding on prey located in front of it, it can also perform quick strikes to either side.
Once the salamander has its prey trapped, it pulls it to the back of the jaw to perform an even stronger bite, preventing its would-be victim from escaping. The authors believe that this skill may be related to the architecture of the creature’s skull, since unlike most salamanders, it does not have bone connecting its maxilla with its anterior quadrato-squamosal region.
Using the model to learn how bite mechanics evolved
Fortuny, along with colleagues from the Universitat Politècnica de Catalunya – BarcelonaTech in Spain, the University of Vienna’s Department of Integrative Zoology and the Institute of Systematic Zoology and Evolutionary Biology at Friedrich-Schiller-University Jena in Germany, believe that the discovery could shed new light on how early tetrapods and amphibians fed.
“Jaw prehension… and ‘secondary’ bites, also called ‘manipulation bites’ (i.e. holding, subduing or crushing prey after initial capture), are essential feeding mechanisms in extant amphibians and are performed both on land and in water,” the authors wrote. “Capturing prey by direct bites has also been suggested to represent the ancestral terrestrial prey capture mode in early tetrapods that evolved from aquatic feeding modes.”
“To improve grip when capturing prey by the jaws, some groups of early amphibians had a well-developed labyrinth tooth structure, with different teeth rows on the skull and jaws and, in some groups, fangs that probably further helped to catch and kill the prey,” they added. “Accordingly, form and function of the biting system not only determine the success of energy uptake in extant amphibians but also played an essential role during the evolution of tetrapods.”
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