Scaling and development of elastic mechanisms: the tiny strikes of larval mantis shrimp

Latch-mediated spring actuation (LaMSA) is used by small organisms to produce high acceleration movements. Mathematical models predict that acceleration increases as LaMSA systems decrease in size. Adult mantis shrimp use a LaMSA mechanism in their raptorial appendages to produce extremely fast strikes. Until now, however, it was unclear whether mantis shrimp at earlier life-history stages also strike using elastic recoil and latch mediation. We tested whether larval mantis shrimp (Gonodactylaceus falcatus) use LaMSA and, because of their smaller size, achieve higher strike accelerations than adults of other mantis shrimp species. Based on microscopy and kinematic analyses, we discovered that larval G. falcatus possess the components of, and actively use, LaMSA during their fourth larval stage, which is the stage of development when larvae begin feeding. Larvae performed strikes at high acceleration and speed (mean: 4.133×105 rad s−2, 292.7 rad s−1; 12 individuals, 25 strikes), which ar...闩锁介导弹簧驱动（Latch-mediated spring actuation, LaMSA）是小型生物用以产生高加速度运动的机制。数学模型预测，LaMSA系统的尺寸越小，其可实现的加速度越高。成年螳螂虾会在其掠足中借助LaMSA机制完成极速攻击。然而此前学界尚未明确，处于生活史早期阶段的螳螂虾是否同样通过弹性回弹与闩锁介导的方式发起攻击。本研究以镰状猛虾蛄（Gonodactylaceus falcatus）的幼虫为对象，验证其是否采用LaMSA机制完成攻击，并验证其因体型更小是否能比其他物种的成年螳螂虾获得更高的攻击加速度。通过显微镜观察与运动学分析，我们发现镰状猛虾蛄幼虫在第四幼虫期（即幼虫开始进食的发育阶段）不仅具备LaMSA的结构组分，还会主动使用该机制。幼虫的攻击动作展现出极高的加速度与角速度（平均值：4.133×10^5 rad·s^-2，292.7 rad·s^-1；共观测12只个体、25次攻击动作），其相关研究结果……