van der Meijden Arie, Kleinteich Thomas
CIBIO Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Vila do Conde, Portugal.
Department of Zoology, Functional Morphology and Biomechanics, Kiel, Germany.
J Anat. 2017 Apr;230(4):497-509. doi: 10.1111/joa.12582. Epub 2016 Dec 28.
Scorpions have elongated metasomas that bear a telson, which is used as a stinger for venom injection. There is a remarkable diversity in the use of the stinger among scorpions, comprising defensive behavior, prey subjugation and mating. This diversity could be reflected by the shape of the telson, as different stinging behaviors will result in very different functional demands. Here we explored the diversity of telson shapes in scorpions by providing morphological measurements, such as curvature and tip angle, as well as by testing stingers under load using finite element analysis (FEA). FEA models were loaded with forces scaled to the surface area of the models, to allow comparison of the relative strain energy based on shape alone. Load force angle was rotated to identify the optimal stinging angle based on the lowest strain energy. Aculeus length and mean aculeus height correlated with minimal strain energy. Optimal stinging angle correlated with tip angle, and differed from the tip angle by about 28.4 ± 6.22 °. We found that species that are more venomous have long aculei (stinger barbs) with a larger radius of curvature. FEA models of these longer aculei showed basal stress concentrations, indicating a potential greater risk of basal breakage due to shape alone. Telsons with shorter and thicker aculeus shapes showed stress concentrations at the tip only. Despite these marked differences in shape, we found no difference in the scaled strain energy between groups of species that are more venomous and less venomous groups of species. These results show that scorpion stingers may be biomechanically optimized, and this may indicate different usage of the stinger in different species.
蝎子具有细长的后体，后体末端有一个尾节，用作注入毒液的毒刺。蝎子使用毒刺的方式存在显著差异，包括防御行为、制服猎物和交配。这种差异可能通过尾节的形状反映出来，因为不同的蜇刺行为会导致截然不同的功能需求。在这里，我们通过提供形态测量数据，如曲率和尖端角度，以及使用有限元分析（FEA）在负载下测试毒刺，来探索蝎子尾节形状的多样性。有限元分析模型加载的力按模型表面积进行缩放，以便仅基于形状比较相对应变能。旋转加载力角度以根据最低应变能确定最佳蜇刺角度。毒刺长度和平均毒刺高度与最小应变能相关。最佳蜇刺角度与尖端角度相关，且与尖端角度相差约28.4±6.22°。我们发现毒性更强的物种具有长毒刺（毒刺倒钩），其曲率半径更大。这些较长毒刺的有限元分析模型显示基部有应力集中，表明仅因形状就可能有更大的基部断裂风险。毒刺形状较短且较粗的尾节仅在尖端显示应力集中。尽管形状存在这些显著差异，但我们发现毒性较强的物种组和毒性较弱的物种组之间的缩放应变能没有差异。这些结果表明，蝎子的毒刺可能在生物力学上得到了优化，这可能表明不同物种中毒刺的使用方式不同。
