Department of Mammalogy and Paleoanthropology, Center of Natural History (CeNak), Universität Hamburg, Martin-Luther-King-Platz 3, 20146, Hamburg, Germany.
Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 9, 24118, Kiel, Germany.
Sci Rep. 2021 Nov 23;11(1):22775. doi: 10.1038/s41598-021-02102-8.
The radula, a chitinous membrane with embedded tooth rows, is the molluscan autapomorphy for feeding. The morphologies, arrangements and mechanical properties of teeth can vary between taxa, which is usually interpreted as adaptation to food. In previous studies, we proposed about trophic and other functional specialisations in taenioglossan radulae from species of African paludomid gastropods. These were based on the analysis of shape, material properties, force-resistance, and the mechanical behaviour of teeth, when interacting with an obstacle. The latter was previously simulated for one species (Spekia zonata) by the finite-element-analysis (FEA) and, for more species, observed in experiments. In the here presented work we test the previous hypotheses by applying the FEA on 3D modelled radulae, with incorporated material properties, from three additional paludomid species. These species forage either on algae attached to rocks (Lavigeria grandis), covering sand (Cleopatra johnstoni), or attached to plant surface and covering sand (Bridouxia grandidieriana). Since the analysed radulae vary greatly in their general size (e.g. width) and size of teeth between species, we additionally aimed at relating the simulated stress and strain distributions with the tooth sizes by altering the force/volume. For this purpose, we also included S. zonata again in the present study. Our FEA results show that smaller radulae are more affected by stress and strain than larger ones, when each tooth is loaded with the same force. However, the results are not fully in congruence with results from the previous breaking stress experiments, indicating that besides the parameter size, more mechanisms leading to reduced stress/strain must be present in radulae.
齿舌，一种带有嵌入式齿列的几丁质膜，是软体动物特有的进食器官。牙齿的形态、排列和机械性能在不同的分类群之间可能会有所不同，通常被解释为对食物的适应。在之前的研究中，我们提出了非洲沼蛤腹足类物种的 taenioglossan 齿舌在营养和其他功能方面的特化。这些特化是基于对形状、材料特性、阻力和牙齿与障碍物相互作用时的机械行为的分析得出的。以前，对一种物种（Spekia zonata）的后一种特性是通过有限元分析（FEA）进行模拟的，而对更多的物种，则是通过实验观察到的。在本文中，我们通过将包含材料特性的 3D 建模齿舌应用于另外三个 paludomid 物种的 FEA，来检验之前的假设。这些物种的食物来源要么是附着在岩石上的藻类（Lavigeria grandis），要么是覆盖在沙子上的Cleopatra johnstoni，要么是附着在植物表面并覆盖在沙子上的Bridouxia grandidieriana。由于分析的齿舌在整体尺寸（例如宽度）和物种间牙齿尺寸上差异很大，我们还旨在通过改变力/体积，将模拟的应力和应变分布与牙齿尺寸联系起来。为此，我们再次将 S. zonata 纳入本研究。我们的 FEA 结果表明，当每个牙齿都承受相同的力时，较小的齿舌比较大的齿舌更容易受到应力和应变的影响。然而，结果与之前的断裂应力实验结果不完全一致，这表明除了尺寸参数外，齿舌中还必须存在更多导致应力/应变降低的机制。
