Anatomical adaptations of the respiratory system of the sandfish (Scincus scincus)
Zusammenfassung der Projektergebnisse
The sandfish lizard (Squamata Scincidae: Scincus scincus (Linnaeus, 1758)) spends nearly its whole life in aeolian sand and only comes to the surface for foraging, defecating and mating. It was not understood how the animal can respire without sand particles entering its respiratory organs when buried under thick layers of sand. In this work, we integrated biological studies, computational calculations and physical experiments to understand this phenomenon. We investigated the basic parameters of its respiratory physiology – pulmonary volumes, oxygen consumption and carbon dioxide production – and the physical properties of its natural habitat. The latter were also simulated using a mathematical model, which was then applied to a more naturalistic system. The lungs, and thus the tidal volumes, of the sandfish are very small, and its oxygen consumption and carbon dioxide production are correspondingly low. Our simulation suggests that the diffusion of gases through sand alone is sufficient to fully sustain physiological conditions. The animal’s low need for oxygen enables it to inhabit a large biotope within the sandy desert, where it can passively regulate its body temperature (and consequently its metabolism), thus reducing its need for food and water, and where it can rest in locations that are safe from predators. We present detailed analysis of oxygen and carbondioxyde in lose aeolian sand, physiological measurements, including the ventilation pattern and a 3-dimensional model of the upper respiratory system based on a detailed histological analysis. A 3D-printed version of this model was used in combination with characteristic ventilation patterns for computational calculations and fluid mechanics experiments. Calculating the velocity field we identified a sharp decrease in velocity in the anterior part of the nasal cavity where mucus and cilia are present. The experiments with the 3D-printed model validate the calculations: Particles, if present, were found only in the same area as suggested by the computations. We postulate that the sandfish has an aerodynamic filtering system, more specifically, that the characteristic morphology of the respiratory channel coupled with specific ventilation patterns prevents particles from entering the lungs.
Projektbezogene Publikationen (Auswahl)
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(2015) Respiratory physiology of the sandfish (Squamata: Scincidae: Scincus scincus) with special reference to subharenal breathing. Salamandra 51(4): 326–334
Boštjan Vihar, Christoph Wolf, Wolfgang Böhme, Florian Fiedler & Werner Baumgartner
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(2016) Adaptation to life in aeolian sand: How the sandfish lizard Scincus scincus prevents sand particles from entering its lungs. Journal of Experimental Biology JEXBIO/2016/138107 (in press)
Anna Theresia Theresia Stadler, Boštjan Vihar, Mathias Guenther, Michaela Huemer, Martin Riedl, Stephanie Shamiyeh, Bernhard Mayrhofer, Wolfgang Böhme & Werner Baumgartner
