Linkage mechanics and power amplification of the mantis shrimp's strike

Abstract

SUMMARY Mantis shrimp (Stomatopoda) generate extremely rapid and forceful predatory strikes through a suite of structural modifications of their raptorial appendages. Here we examine the key morphological and kinematic components of the raptorial strike that amplify the power output of the underlying muscle contractions. Morphological analyses of joint mechanics are integrated with CT scans of mineralization patterns and kinematic analyses toward the goal of understanding the mechanical basis of linkage dynamics and strike performance. We test whether a four-bar linkage mechanism amplifies rotation in this system and find that the rotational amplification is approximately two times the input rotation, thereby amplifying the velocity and acceleration of the strike. The four-bar model is generally supported, although the observed kinematic transmission is lower than predicted by the four-bar model. The results of the morphological, kinematic and mechanical analyses suggest a multi-faceted mechanical system that integrates latches, linkages and lever arms and is powered by multiple sites of cuticular energy storage. Through reorganization of joint architecture and asymmetric distribution of mineralized cuticle, the mantis shrimp's raptorial appendage offers a remarkable example of how structural and mechanical modifications can yield power amplification sufficient to produce speeds and forces at the outer known limits of biological systems.

Cold‐blooded snipers: thermal independence of ballistic tongue projection in the salamander Hydromantes platycephalus

“…Among insects, snow fleas have been found to jump with a high performance at 0°C, possibly making use of energy storage in the resilin of their limb articulations (Burrows, 2011). Many other animal movements which make use of elastic‐recoil mechanisms to enhance mechanical power output (Roberts and Azizi, 2011) may benefit from thermal independence, including striking in mantis shrimp (Patek et al, 2007; Zack et al, 2009), jaw closure in trap jaw ants (Gronenberg, '96; Patek et al, 2006), jumping in frogs (Roberts and Marsh, 2003) and insects (Bennet‐Clark and Lucey, '67; Rothschild et al, '75; Bennet‐Clark, '76; Burrows, 2010), and suction feeding in pipefish (Van Wassenbergh et al, 2008). …”

Mechanical sensitivity reveals evolutionary dynamics of mechanical systems

“…KT is the ratio of the rotation of the output link (link 3: carpus) to the input link (link 2: meral-V). However, KT is a dynamic metric that changes over the course of rotation as the orientation of the linkage shifts [32]. Minimum KT refers to the lowest value of KT for a given linkage over the course of its full rotation as defined by the meral-V excursion.…”

Micro-computed tomography: Introducing new dimensions to taxonomy

“…Particularly, invertebrate zoologists have started to employ micro-MRI (for an overview of taxa imaged so far with MRI see Ziegler et al 2011a) and micro-CT. Several studies already show the potential of these methods to deliver new data to test taxonomic hypotheses (Heim and Nickel 2010, McPeek et al 2011, Csösz 2012). They also provide new insights into morphology and anatomy (Golding and Jones 2006, Holford 2008, Dinley et al 2010, Huckstorf and Wirkner 2011), functional morphology (Alba-Tercedor and Sánchez-Tocino 2011, Bond et al 2008, Nickel et al 2006, Patek et al 2007, Wilhelm et al 2011) and developmental studies (Postnov et al 2002, Marxen et al 2007, Puce et al 2012) by studying species through a virtual, three-dimensional model. In palaeobiology, the technique is, for example, frequently used to reveal the morphology and even anatomy of fossilised organisms that cannot be removed from their enclosure medium (Dierick et al 2007, Dunlop et al 2011, Hendrickx et al 2006, Molineux et al 2007, Penney et al 2007, Sutton 2008).…”