Even the most powerful muscles contract too slowly and over distances too short to achieve the incredible speeds and accelerations that we see in the many rapid predatory movements of animals. Humans circumvent these limitations with engineered systems like the crossbow, in which slow arm movement is transformed into rapid arrow movement through the elastic energy storage of the bow and rapid energy release via a latch. Repeatedly over evolutionary history, animals have overcome the limits of muscle contractions through power amplification mechanisms similar to that of the bow and arrow, and yet scientists lack a broad understanding of the interplay between the evolutionary variation in these systems and the underlying physical principles of power amplification. This research project focuses on mantis shrimp (Stomatopoda), which generate among the fastest and most forceful predatory movements in the animal kingdom. Raptorial strikes occur within several milliseconds and can reach speeds of over 20 m/s; some species can strike with impact forces of over 1000 N (thousands of times their body weight). These impressive movements are controlled by slowly contracting muscles that activate a network of power amplification structures including springs, latches, linkages and lever arms. This power amplification system is conserved across the 450 species of stomatopods, yet their raptorial appendages are remarkably diverse, ranging from spiny and barbed spears to hatchets and hammers. To address the broad evolutionary patterns and the fundamental physical principles of biological power amplification, this project integrates three approaches: (1) physiological and kinematic analyses of morphology and performance across species; (2) application of a model that integrates and accounts for the relative roles of springs, linkages and lever arms in power amplification and performance; and (3) comparative analyses of the dynamics of the model variables compared to their actual variation observed across species. Through the integration of physiology, physics and evolutionary patterns, the results of this research will provide fundamental insights into biological power-amplified systems, in general. The broader impacts of this proposal include that it is integrative, combines biology and engineering principles, and focuses on the training and education of a diverse group of students including women and underrepresented minorities. The findings from this research will be provided to the public through NSF-funded programs (e.g., Understanding Evolution) and collaborations with the scientific press.
