UNVEILING SUCTION-FEEDING MECHANISMS IN A HYBRID GIANT SALAMANDER (ANDRIAS JAPONICUS × ANDRIAS CF. DAVIDIANUS) THROUGH COMPUTATIONAL FLUID DYNAMICS
Suction-feeding is a method of prey capture in fluids by sucking the prey into the predator’s mouth. This specialised mechanism has been employed by various taxa, including the salamander group Cryptobranchidae, since the Paleocene period. Understanding the biomechanics of suction-feeding is valuable for analysing the physical and morphological mechanisms that support it, as well as its influence on the evolution of feeding strategies in aquatic amphibians, given that suction-feeding has proven to be a highly successful mechanism.
In this study, we developed a two-dimensional Computational Fluid Dynamics (CFD) model of suction-feeding based on micro-CT scans of a first-generation hybrid Andrias davidianus x Andrias japonicus from the Okayama prefecture, Japan. Transient CFD simulations were conducted using unstructured dynamic meshes, along with an overset approach, which allows bidirectional interaction between the prey and the surrounding fluid. Translational (anterior–posterior) and rotational (hinge-like opening around the jaw joint) movements of the skull and lower jaw were implemented, also considering surface deformation.
Additionally, the depression of the hyoid was considered. The inertial properties of the dynamic mesh were defined according to data from previous studies on Chinese giant salamander (Andrias davidianus). Variables such as prey position, size, and weight were parameterised. The results reveal that cranial geometry, the hyoid apparatus, and prey properties play a crucial role in generating negative pressures that facilitate feeding.
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