PATEK, Sheila N.*; BAIO, Joseph; SUMMERS, Adam; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Irvine: Springs, linkages and latches: a mechanical model of the mantis shrimp�s raptorial appendage

Mantis shrimp (Stomatopoda) use a remarkable spring-loaded click mechanism in their raptorial appendages to rapidly capture and process prey. In some mantis shrimp species, the raptorial appendage is specialized for spearing evasive prey, whereas in other species the limb is specialized for smashing hard-shelled prey. Here we propose and test a linkage model that predicts the speed and force outputs within a �smasher� species, the peacock mantis shrimp Odontodactylus scyllarus , based on kinematic and morphometric analyses across multiple individuals. The model focuses on a sliding joint which delivers stored elastic strain energy to the rotation of the striking limb and amplifies the angular rotation of the limb by a factor of two. Using mechanical tests, the elastic energy storage of an exoskeletal saddle-shaped structure in the meral segment was measured. We found that the flexion of this saddle-shaped spring only stores a fraction of the elastic strain energy necessary for the strike, and therefore a second additional region of cuticular elastic energy storage in the meral segment is proposed. Through the use of 3-D CT scans, we dynamically visualized the movable elements and relative mineralization of specific structures. The results of this study provide a model of a mechanically integrated and highly potent prey capture system. With this model, we can begin to examine the morphological variation underlying the fascinating diversity of prey capture strategies across stomatopod species.