Modelling tooth–prey interactions in sharks: the importance of dynamic testing

The shape of shark teeth varies among species, but traditional testing protocols have revealed no predictive relationship between shark tooth morphology and performance. We developed a dynamic testing device to quantify cutting performance of teeth. We mimicked head-shaking behaviour in feeding large sharks by attaching teeth to the blade of a reciprocating power saw fixed in a custom-built frame. We tested three tooth types at biologically relevant speeds and found differences in tooth cutting ability and wear. Teeth from the bluntnose sixgill (Hexanchus griseus) showed poor cutting ability compared with tiger (Galeocerdo cuvier), sandbar (Carcharhinus plumbeus) and silky (C. falciformis) sharks, but they also showed no wear with repeated use. Some shark teeth are very sharp at the expense of quickly dulling, while others are less sharp but dull more slowly. This demonstrates that dynamic testing is vital to understanding the performance of shark teeth.不同鲨鱼物种的牙齿形态存在差异，但传统测试方案尚未揭示鲨鱼牙齿形态与性能之间的可预测关联。我们研发了一套动态测试装置以量化牙齿的切割性能。我们将牙齿安装于定制框架内的往复式电锯刀片之上，以此模拟大型鲨鱼进食时的摇头动作。我们在符合生物学相关的测试速度下对三种牙齿类型展开测试，结果发现不同牙齿的切割能力与磨损程度存在显著差异。钝吻六鳃鲨（Hexanchus griseus）的牙齿相较于虎鲨（Galeocerdo cuvier）、沙洲鲨（Carcharhinus plumbeus）与丝鲨（C. falciformis），切割能力较弱，但在反复使用后不会产生磨损。部分鲨鱼牙齿具备极高的锋利度，但会快速钝化；而另一些牙齿锋利度稍低，却能更缓慢地发生磨损。该研究结果表明，动态测试对于理解鲨鱼牙齿的性能至关重要。