Deadly strike mechanism of a mantis shrimp

Guidelines derived from biomineralized tissues for design and construction of high-performance biomimetic materials: from weak to strong

Living organisms in nature have undergone continuous evolution over billions of years, resulting in the formation of high-performance fracture-resistant biomineralized tissues such as bones and teeth to fulfill mechanical and biological functions, despite the fact that most inorganic biominerals that constitute biomineralized tissues are weak and brittle. During the long-period evolution process, nature has evolved a number of highly effective and smart strategies to design chemical compositions and structures of biomineralized tissues to enable superior properties and to adapt to surrounding environments. Most biomineralized tissues have hierarchically ordered structures consisting of very small building blocks on the nanometer scale (nanoparticles, nanofibers or nanoflakes) to reduce the inherent weaknesses and brittleness of corresponding inorganic biominerals, to prevent crack initiation and propagation, and to allow high defect tolerance. The bioinspired principles derived from biomineralized tissues are indispensable for designing and constructing high-performance biomimetic materials. In recent years, a large number of high-performance biomimetic materials have been prepared based on these bioinspired principles with a large volume of literature covering this topic. Therefore, a timely and comprehensive review on this hot topic is highly important and contributes to the future development of this rapidly evolving research field. This review article aims to be comprehensive, authoritative, and critical with wide general interest to the science community, summarizing recent advances in revealing the formation processes, composition, and structures of biomineralized tissues, providing in-depth insights into guidelines derived from biomineralized tissues for the design and construction of high-performance biomimetic materials, and discussing recent progress, current research trends, key problems, future main research directions and challenges, and future perspectives in this exciting and rapidly evolving research field.

Morphological and structural characteristics of the elytra reduce impact damage to ladybird beetles

Beetle elytra act as natural protective covers and effectively shield their flexible abdomens and fragile hindwings from damage. The existing studies have attributed this contribution of the elytra to its honeycomb structures. In this combined experimental and theoretical study, we used the seven-spotted ladybird beetle to demonstrate that both biological morphology and the hollow structure of the dome-like elytra combined to reduce damage during falling. The falling ladybird beetles had a high probability (59.52%) of hitting the ground with the costal edge of the elytra. This strategy could assist with converting the translational energy into rotational kinetic energy, resulting in the reduction of the impulse during falling. In addition, the hollow structures on the elytra could further absorb the residual impact energy. In the future, this biological paradigm could be used as a basis for the development of falling/landing techniques for advanced robots.

Performance of 3D printing biomimetic conch shell and pearl shell hybrid design composites under quasi-static three-point bending load

The failure process of biomimetic hybrid design composite composed of layers of conch shell and pearl shell was studied through quasi-static three-point bending experiments and numerical simulations. The biomimetic conch shell structure with inclined angles serves as the upper layer of the hybrid structure, while the biomimetic pearl shell structure with traditional brick and mud structure serves as the lower layer of the hybrid structure, forming a hybrid design structure. Four inclined angles were designed for the structural units of the conch shell, namely 15°, 30°, 45°, and 60°. Twenty-four specimens (six specimens for each inclined angle) were prepared using 3D printing technology using both soft and hard matrix materials. The influence of different inclined angles on the fracture strength, fracture toughness, and energy absorption of hybrid design structures was experimentally studied. The biomimetic hybrid design composite specimen with a notch is placed between two supporting rollers, and a loading indenter acts at mid-span. All twenty-four specimens were notched with a triangular tip and a rectangular bottom. A loading rate of 1 mm/min is used to avoid the viscoelastic effect of the composite materials. Details of the specimens, the experimental set-up and procedure are discussed in this paper. Complementary to the experimental studies, an extensive numerical investigation was carried out to study the influence of the aspect ratio of brick and mud units on the fracture initiation and failure of hybrid design structures. The causes of crack initiation and propagation, and failure modes in biomimetic hybrid design structures were postulated. These numerical findings help in reinforcing the experimental results and provide crucial information to enhance further research in this exciting area.

Honeybee comb-inspired stiffness gradient-amplified catapult for solid particle repellency

Natural surfaces that repel foreign matter are ubiquitous and crucial for living organisms. Despite remarkable liquid repellency driven by surface energy in many organisms, repelling tiny solid particles from surfaces is rare. The main challenge lies in the unfavourable scaling of inertia versus adhesion in the microscale and the inability of solids to release surface energy. Here we report a previously unexplored solid repellency on a honeybee's comb: a catapult-like effect to immediately eject pollen after grooming dirty antennae for self-cleaning. Nanoindentation tests revealed the 38-μm-long comb features a stiffness gradient spanning nearly two orders of magnitude from ~25 MPa at the tip to ~645 MPa at the base. This significantly augments the elastic energy storage and accelerates the subsequent conversion into kinetic energy. The reinforcement in energy storage and conversion allows the particle's otherwise weak inertia to outweigh its adhesion, thereby suppressing the unfavourable scaling effect and realizing solid repellency that is impossible in conventional uniform designs. We capitalize on this to build an elastomeric bioinspired stiffness-gradient catapult and demonstrate its generality and practicality. Our findings advance the fundamental understanding of natural catapult phenomena with the potential to develop bioinspired stiffness-gradient materials, catapult-based actuators and robotic cleaners.

Development of a Cavitation Generator Mimicking Pistol Shrimp

Pistol shrimp generate cavitation bubbles. Cavitation impacts due to bubble collapses are harmful phenomena, as they cause severe damage to hydraulic machinery such as pumps and valves. However, cavitation impacts can be utilized for mechanical surface treatment to improve the fatigue strength of metallic materials, which is called "cavitation peening". Through conventional cavitation peening, cavitation is generated by a submerged water jet, i.e., a cavitating jet or a pulsed laser. The fatigue strength of magnesium alloy when treated by the pulsed laser is larger than that of the jet. In order to drastically increase the processing efficiency of cavitation peening, the mechanism of pistol shrimp (specifically when used to create a cavitation bubble), i.e., Alpheus randalli, was quantitatively investigated. It was found that a pulsed water jet generates a cavitation bubble when a shrimp snaps its claws. Furthermore, two types of cavitation generators were developed, namely, one that uses a pulsed laser and one that uses a piezo actuator, and this was achieved by mimicking a pistol shrimp. The generation of cavitation bubbles was demonstrated by using both types of cavitation generators: the pulsed laser and the piezo actuator.

Bio-inspired apparatus to produce luminescent cavitation in a rigid walled chamber

A mechanical device inspired by the rapid rotational motion of the pistol shrimp plunger has been developed to experimentally study the contraction/expansion dynamics of a gas bubble inside a confined liquid volume and in the vicinity of solid surfaces. The apparatus consists of a limb with a V-shaped end, which fits into a socket forming a cylindrical compression chamber. Air bubbles of different sizes and in different positions inside the chamber were seeded to study their shape evolution in liquids when subjected to pressure pulses induced by the limb closure. By changing the standoff and curvature parameters, as well as the closing power of the limb it was possible to control the dynamical behavior of the cavity. Four stages describing the dynamic behavior of the bubble were found: 1) A slight expansion-contraction stage accompanied by very weak volumetric oscillations. 2) First compression stage. The formation of gas and liquid micro-jets is observed when the vertical symmetry axis of the bubble is initially located outside of the chamber symmetry axis, on the other hand, when there is a coincidence between these axes, the bubble only contracts exhibiting non-spherical shapes, alternating between oblate and prolate spheroidal structures. 3) An expansion stage where the cavity reaches the walls of the chamber exhibiting irregular shapes on its surface. 4) Second compression stage. This process begins when the limb rebounds and stops sealing the chamber allowing a jet of liquid to enter from the fluid medium outside, inducing a very violent collapse accompanied by the emission of light. The proposed technique represents a novel alternative to study the dynamic evolution of bubbles near and on solid boundaries of various geometries. Other attractive features of the apparatus are its low manufacturing cost, simple design and compact size which makes it easily portable.

A Conceptual Exploration of Hamstring Muscle-Tendon Functioning during the Late-Swing Phase of Sprinting: The Importance of Evidence-Based Hamstring Training Frameworks

An eccentrically lengthening, energy-absorbing, brake-driven model of hamstring function during the late-swing phase of sprinting has been widely touted within the existing literature. In contrast, an isometrically contracting, spring-driven model of hamstring function has recently been proposed. This theory has gained substantial traction within the applied sporting world, influencing understandings of hamstring function while sprinting, as well as the development and adoption of certain types of hamstring-specific exercises. Across the animal kingdom, both spring- and motor-driven muscle-tendon unit (MTU) functioning are frequently observed, with both models of locomotive functioning commonly utilising some degree of active muscle lengthening to draw upon force enhancement mechanisms. However, a method to accurately assess hamstring muscle-tendon functioning when sprinting does not exist. Accordingly, the aims of this review article are three-fold: (1) to comprehensively explore current terminology, theories and models surrounding muscle-tendon functioning during locomotion, (2) to relate these models to potential hamstring function when sprinting by examining a variety of hamstring-specific research and (3) to highlight the importance of developing and utilising evidence-based frameworks to guide hamstring training in athletes required to sprint. Due to the intensity of movement, large musculotendinous stretches and high mechanical loads experienced in the hamstrings when sprinting, it is anticipated that the hamstring MTUs adopt a model of functioning that has some reliance upon active muscle lengthening and muscle actuators during this particular task. However, each individual hamstring MTU is expected to adopt various combinations of spring-, brake- and motor-driven functioning when sprinting, in accordance with their architectural arrangement and activation patterns. Muscle function is intricate and dependent upon complex interactions between musculoskeletal kinematics and kinetics, muscle activation patterns and the neuromechanical regulation of tensions and stiffness, and loads applied by the environment, among other important variables. Accordingly, hamstring function when sprinting is anticipated to be unique to this particular activity. It is therefore proposed that the adoption of hamstring-specific exercises should not be founded on unvalidated claims of replicating hamstring function when sprinting, as has been suggested in the literature. Adaptive benefits may potentially be derived from a range of hamstring-specific exercises that vary in the stimuli they provide. Therefore, a more rigorous approach is to select hamstring-specific exercises based on thoroughly constructed evidence-based frameworks surrounding the specific stimulus provided by the exercise, the accompanying adaptations elicited by the exercise, and the effects of these adaptations on hamstring functioning and injury risk mitigation when sprinting.

Evidence for multi-scale power amplification in skeletal muscle

Many animals use a combination of skeletal muscle and elastic structures to amplify power output for fast motions. Among vertebrates, tendons in series with skeletal muscle are often implicated as the primary power-amplifying spring, but muscles contain elastic structures at all levels of organization, from the muscle tendon to the extracellular matrix to elastic proteins within sarcomeres. The present study used ex vivo muscle preparations in combination with high-speed video to quantify power output, as the product of force and velocity, at several levels of muscle organization to determine where power amplification occurs. Dynamic ramp-shortening contractions in isolated frog flexor digitorum superficialis brevis were compared with isotonic power output to identify power amplification within muscle fibers, the muscle belly, free tendon and elements external to the muscle tendon. Energy accounting revealed that artifacts from compliant structures outside of the muscle-tendon unit contributed significant peak instantaneous power. This compliance included deflection of clamped bone that stored and released energy contributing 195.22±33.19 W kg-1 (mean±s.e.m.) to the peak power output. In addition, we found that power detected from within the muscle fascicles for dynamic shortening ramps was 338.78±16.03 W kg-1, or approximately 1.75 times the maximum isotonic power output of 195.23±8.82 W kg-1. Measurements of muscle belly and muscle-tendon unit also demonstrated significant power amplification. These data suggest that intramuscular tissues, as well as bone, have the capacity to store and release energy to amplify whole-muscle power output.

Biomineralization of mantis shrimp dactyl club following molting: Apatite formation and brominated organic components

The stomatopod Odontodactylus scyllarus uses weaponized club-like appendages to attack its prey. These clubs are made of apatite, chitin, amorphous calcium carbonate, and amorphous calcium phosphate organized in a highly hierarchical structure with multiple regions and layers. We follow the development of the biomineralized club as a function of time using clubs harvested at specific times since molting. The clubs are investigated using a broad suite of techniques to unravel the biomineralization history of the clubs. Nano focus synchrotron x-ray diffraction and x-ray fluorescence experiments reveal that the club structure is more organized with more sub-regions than previously thought. The recently discovered impact surface has crystallites in a different size and orientation than those in the impact region. The crystal unit cell parameters vary to a large degree across individual samples, which indicates a spatial variation in the degree of chemical substitution. Energy dispersive spectroscopy and Raman spectroscopy show that this variation cannot be explained by carbonation and fluoridation of the lattice alone. X-ray fluorescence and mass spectroscopy show that the impact surface is coated with a thin membrane rich in bromine that forms at very initial stages of club formation. Proteomic studies show that a fraction of the club mineralization protein-1 has brominated tyrosine suggesting that bromination of club proteins at the club surface is an integral component of the club design. Taken together, the data unravel the spatio-temporal changes in biomineral structure during club formation. STATEMENT OF SIGNIFICANCE: Mantis shrimp hunt using club-like appendages that contain apatite, chitin, amorphous calcium carbonate, and amorphous calcium phosphate ordered in a highly hierarchical structure. To understand the formation process of the club we analyze clubs harvested at specific times since molting thereby constructing a club formation map. By combining several methods ranging from position resolved synchrotron X-ray diffraction to proteomics, we reveal that clubs form from an organic membrane with brominated protein and that crystalline apatite phases are present from the very onset of club formation and grow in relative importance over time. This reveals a complex biomineralization process leading to these fascinating biomineralized tools.

A study of a bio-inspired impact resistant carbon fiber laminate with a sinusoidal helicoidal structure in the mandibles of trap-jaw ants

The majority of living organisms demonstrate remarkable attributes and have evolved effective mechanisms for synthesizing impact-resistant and damage-tolerant structures. One exemplary instance is the rapid mandible strikes exhibited by trap-jaw ants, which are a highly aggressive species of terrestrial social organisms. An impact-resistant sinusoidal helicoidal architecture is discovered in the mandibles of trap-jaw ants. The bioinspired laminate with a bi-sinusoidal helicoidal structure was manufactured using unidirectional carbon fiber prepreg by mold press forming. This study examines the impact resistance and damage tolerance of a bionic laminate through low velocity impact, computed tomography, and compression after impact tests. The results demonstrate that bionic laminates effectively limit damage propagation within the plane while enhancing energy dissipation capacity. The sinusoidal helicoidal configuration enhances cushioning capability against impact forces, retards penetration under higher loads, hinders crack propagation, and improves residual strength. Bionic laminates provide a valuable solution for damage tolerance through the resistance to through-the-thickness loads. STATEMENT OF SIGNIFICANCE: Helicoidal and sinusoidal helicoidal microstructures have been identified in the cross-section of the jaws of trap-jaw ants. The multiple waviness ratio parameters are designed for fabricating a sinusoidal helicoidal structure laminate using unidirectional carbon fiber prepreg through the mold press forming technique. This results in a damage-tolerant mechanism characterized by reduced delamination damage, which leads to a stiffer mechanical response. Meanwhile, it enhances resistance to crack propagation, leading to the formation of discontinuous delamination areas and the accumulation of sub-critical failures. Additionally, the sinusoidal helicoidal structure laminate combines the cushioning performance of bi-sinusoidal arrangements with the enhanced impact resistance of helical arrangements. This design delays penetration at higher loads, resulting in increased residual strength.

Biomimetic Silk Architectures Outperform Animal Horns in Strength and Toughness

Structural biomimicry is an intelligent approach for developing lightweight, strong, and tough materials (LSTMs). Current fabrication technologies, such as 3D printing and two-photon lithography often face challenges in constructing complex interlaced structures, such as the sinusoidal crossed herringbone structure that contributes to the ultrahigh strength and fracture toughness of the dactyl club of peacock mantis shrimps. Herein, bioinspired LSTMs with laminated or herringbone structures is reported, by combining textile processing and silk fiber "welding" techniques. The resulting biomimetic silk LSTMs (BS-LSTMs) exhibit a remarkable combination of lightweight with a density of 0.6-0.9 g cm-3 , while also being 1.5 times stronger and 16 times more durable than animal horns. These findings demonstrate that BS-LSTMs are among the toughest natural materials made from silk proteins. Finite element simulations further reveal that the fortification and hardening of BS-LSTMs arise primarily from the hierarchical organization of silk fibers and mechanically transferable meso-interfaces. This study highlights the rational, cost-effective, controllable mesostructure, and transferable strategy of integrating textile processing and fiber "welding" techniques for the fabrication of BS-LSTMs with advantageous structural and mechanical properties. These findings have significant implications for a wide range of applications in biomedicine, mechanical engineering, intelligent textiles, aerospace industries, and beyond.

Research on In-Plane Deformation Performance of Rotating Honeycomb Structures

Most natural materials have rotational and hierarchical properties, so they can show excellent mechanical properties such as shear resistance and impact resistance. In order to further improve the energy absorption characteristics of vibration absorbing structures, a new type of honeycomb structure with integral rotation and group rotation is designed and characterized. The effects of the geometrical parameters of rotation Angle on the impact deformation mode, stress response curve and energy absorption characteristics of the honeycomb structure are studied through numerical simulation and experimental design. The results show that the overall honeycomb performance of 15° is better than that of 0°, the specific energy absorption is the results show that the overall honeycomb performance of 15° is better than that of 0°, the specific energy absorption is increased by 6%, the bearing capacity is increased by 320 N, and the crushing force efficiency is increased by 2%. Compared with the whole cell and the group cell, the specific absorption energy increased by 35%, 73% and 71%. The results of this paper provide a new insight into the impact performance of monolithic and grouped rotating honeycomb structures, which is helpful for the results of this paper provide a new insight into the impact performance of monolithic and grouped rotating honeycomb structures, which is helpful for the optimization of crashworthiness structural design.

Flexible design in the stomatopod dactyl club

The stomatopod is a fascinating animal that uses its weaponized appendage dactyl clubs for breaking mollusc shells. Dactyl clubs are a well studied example of biomineralized hierarchical structures. Most research has focused on the regions close to the action, namely the impact region and surface composed of chitin and apatite crystallites. Further away from the site of impact, the club has lower mineralization and more amorphous phases; these areas have not been as actively studied as their highly mineralized counterparts. This work focuses on the side of the club, in what is known as the periodic and striated regions. A combination of laboratory micro-computed tomography, synchrotron X-ray diffraction mapping and synchrotron X-ray fluorescence mapping has shown that the mineral in this region undergoes the transition from an amorphous to a crystalline phase in some, but not all, clubs. This means that this side region can be mineralized by either an amorphous phase, calcite crystallites or a mixture of both. It was found that when larger calcite crystallites form, they are organized (textured) with respect to the chitin present in this biocomposite. This suggests that chitin may serve as a template for crystallization when the side of the club is fully mineralized. Further, calcite crystallites were found to form as early as 1 week after moulting of the club. This suggests that the side of the club is designed with a significant safety margin that allows for a variety of phases, i.e. the club can function independently of whether the side region has a crystalline or amorphous mineral phase.

Structural damping renders the hawkmoth exoskeleton mechanically insensitive to non-sinusoidal deformations

Muscles act through elastic and dissipative elements to mediate movement, which can introduce dissipation and filtering which are important for energetics and control. The high power requirements of flapping flight can be reduced by an insect's exoskeleton, which acts as a spring with frequency-independent material properties under purely sinusoidal deformation. However, this purely sinusoidal dynamic regime does not encompass the asymmetric wing strokes of many insects or non-periodic deformations induced by external perturbations. As such, it remains unknown whether a frequency-independent model applies broadly and what implications it has for control. We used a vibration testing system to measure the mechanical properties of isolated Manduca sexta thoraces under symmetric, asymmetric and band-limited white noise deformations. The asymmetric and white noise conditions represent two types of generalized, multi-frequency deformations that may be encountered during steady-state and perturbed flight. Power savings and dissipation were indistinguishable between symmetric and asymmetric conditions, demonstrating that no additional energy is required to deform the thorax non-sinusoidally. Under white noise conditions, stiffness and damping were invariant with frequency, suggesting that the thorax has no frequency-dependent filtering properties. A simple flat frequency response function fits our measured frequency response. This work demonstrates the potential of materials with frequency-independent damping to simplify motor control by eliminating any velocity-dependent filtering that viscoelastic elements usually impose between muscle and wing.

A power amplification dyad in seahorses

Throughout evolution, organisms repeatedly developed elastic elements to power explosive body motions, overcoming ubiquitous limits on the power capacity of fast-contracting muscles. Seahorses evolved such a latch-mediated spring-actuated (LaMSA) mechanism; however, it is unclear how this mechanism powers the two complementary functions necessary for feeding: rapidly swinging the head towards the prey, and sucking water into the mouth to entrain it. Here, we combine flow visualization and hydrodynamic modelling to estimate the net power required for accelerating the suction feeding flows in 13 fish species. We show that the mass-specific power of suction feeding in seahorses is approximately three times higher than the maximum recorded from any vertebrate muscle, resulting in suction flows that are approximately eight times faster than similar-sized fishes. Using material testing, we reveal that the rapid contraction of the sternohyoideus tendons can release approximately 72% of the power needed to accelerate the water into the mouth. We conclude that the LaMSA system in seahorses is powered by two elastic elements, the sternohyoideus and epaxial tendons. These elements jointly actuate the coordinated acceleration of the head and the fluid in front of the mouth. These findings extend the known function, capacity and design of LaMSA systems.

Three-dimensional ori-kirigami metamaterials with multistability

Ori-kirigami structures offer a good avenue for designing mechanical metamaterials due to their unique advantage of being independent of material properties and scale limitations. Recently, the scientific community has been greatly interested in exploiting the complex energy landscape of ori-kirigami structures to construct multistable systems and play their valuable role in different applications. Here, we present three-dimensional ori-kirigami structures based on generalized waterbomb units, a cylindrical ori-kirigami structure based on waterbomb units, and a conical ori-kirigami structure based on trapezoidal waterbomb units. We investigate the inherent relationships between the unique kinematics and mechanical properties of these three-dimensional ori-kirigami structures and explore their potential usage as mechanical metamaterials that exhibit negative stiffness, snap-through, hysteresis effects, and multistability. What makes the structures even more attractive is their massive folding stroke, where the conical ori-kirigami structure can obtain a huge folding stroke of more than twice its initial height through penetration of its upper and lower boundaries. This study forms the foundation for designing and constructing three-dimensional ori-kirigami metamaterials based on generalized waterbomb units for various engineering applications.

Giant proteins in a giant cell: Molecular basis of ultrafast Ca2+-dependent cell contraction

The giant single-celled eukaryote, Spirostomum, exhibits one of the fastest movements in the biological world. This ultrafast contraction is dependent on Ca²⁺ rather than ATP and therefore differs to the actin-myosin system in muscle. We obtained the high-quality genome of Spirostomum minus from which we identified the key molecular components of its contractile apparatus, including two major Ca²⁺ binding proteins (Spasmin 1 and 2) and two giant proteins (GSBP1 and GSBP2), which act as the backbone and allow for the binding of hundreds of spasmins. The evidence suggests that the GSBP-spasmin protein complex is the functional unit of the mesh-like contractile fibrillar system, which, coupled with various other subcellular structures, provides the mechanism for repetitive ultrafast cell contraction and extension. These findings improve our understanding of the Ca²⁺-dependent ultrafast movement and provide a blueprint for future biomimicry, design, and construction of this kind of micromachine.

Developing elastic mechanisms: ultrafast motion and cavitation emerge at the millimeter scale in juvenile snapping shrimp

Organisms such as jumping froghopper insects and punching mantis shrimp use spring-based propulsion to achieve fast motion. Studies of elastic mechanisms have primarily focused on fully developed and functional mechanisms in adult organisms. However, the ontogeny and development of these mechanisms can provide important insights into the lower size limits of spring-based propulsion, the ecological or behavioral relevance of ultrafast movement, and the scaling of ultrafast movement. Here, we examined the development of the spring-latch mechanism in the bigclaw snapping shrimp, Alpheus heterochaelis (Alpheidae). Adult snapping shrimp use an enlarged claw to produce high-speed strikes that generate cavitation bubbles. However, until now, it was unclear when the elastic mechanism emerges during development and whether juvenile snapping shrimp can generate cavitation at this size. We reared A. heterochaelis from eggs, through their larval and postlarval stages. Starting 1 month after hatching, the snapping shrimp snapping claw gradually developed a spring-actuated mechanism and began snapping. We used high-speed videography (300,000 frames s-1) to measure juvenile snaps. We discovered that juvenile snapping shrimp generate the highest recorded accelerations (5.8×105±3.3×105 m s-2) for repeated-use, underwater motion and are capable of producing cavitation at the millimeter scale. The angular velocity of snaps did not change as juveniles grew; however, juvenile snapping shrimp with larger claws produced faster linear speeds and generated larger, longer-lasting cavitation bubbles. These findings establish the development of the elastic mechanism and cavitation in snapping shrimp and provide insights into early life-history transitions in spring-actuated mechanisms.

Leveraging big data to uncover the eco-evolutionary factors shaping behavioural development

Mapping the eco-evolutionary factors shaping the development of animals' behavioural phenotypes remains a great challenge. Recent advances in 'big behavioural data' research-the high-resolution tracking of individuals and the harnessing of that data with powerful analytical tools-have vastly improved our ability to measure and model developing behavioural phenotypes. Applied to the study of behavioural ontogeny, the unfolding of whole behavioural repertoires can be mapped in unprecedented detail with relative ease. This overcomes long-standing experimental bottlenecks and heralds a surge of studies that more finely define and explore behavioural-experiential trajectories across development. In this review, we first provide a brief guide to state-of-the-art approaches that allow the collection and analysis of high-resolution behavioural data across development. We then outline how such approaches can be used to address key issues regarding the ecological and evolutionary factors shaping behavioural development: developmental feedbacks between behaviour and underlying states, early life effects and behavioural transitions, and information integration across development.

Blood python (Python brongersmai) strike kinematics and forces are robust to variations in substrate geometry

Snake strikes are some of the most rapid accelerations in terrestrial vertebrates. Generating rapid body accelerations requires high ground reaction forces, but on flat surfaces snakes must rely on static friction to prevent slip. We hypothesize that snakes may be able to take advantage of structures in the environment to prevent their body from slipping, potentially allowing them to generate faster and more forceful strikes. To test this hypothesis, we captured high-speed video and forces from defensive strikes of juvenile blood pythons (Python brongersmai) on a platform that was either open on all sides or with two adjacent walls opposite the direction of the strike. Contrary to our predictions, snakes maintained high performance on open platforms by imparting rearward momentum to the posterior body and tail. This compensatory behavior increases robustness to changes in their strike conditions and could allow them to exploit variable environments.

Geometric latches enable tuning of ultrafast, spring-propelled movements

The smallest, fastest, repeated-use movements are propelled by power-dense elastic mechanisms, yet the key to their energetic control may be found in the latch-like mechanisms that mediate transformation from elastic potential energy to kinetic energy. Here, we tested how geometric latches enable consistent or variable outputs in ultrafast, spring-propelled systems. We constructed a reduced-order mathematical model of a spring-propelled system that uses a torque reversal (over-center) geometric latch. The model was parameterized to match the scales and mechanisms of ultrafast systems, specifically snapping shrimp. We simulated geometric and energetic configurations that enabled or reduced variation of strike durations and dactyl rotations given variation of stored elastic energy and latch mediation. Then, we collected an experimental dataset of the energy storage mechanism and ultrafast snaps of live snapping shrimp (Alpheus heterochaelis) and compared our simulations with their configuration. We discovered that snapping shrimp deform the propodus exoskeleton prior to the strike, which may contribute to elastic energy storage. Regardless of the amount of variation in spring loading duration, strike durations were far less variable than spring loading durations. When we simulated this species' morphological configuration in our mathematical model, we found that the low variability of strike duration is consistent with their torque reversal geometry. Even so, our simulations indicate that torque reversal systems can achieve either variable or invariant outputs through small adjustments to geometry. Our combined experiments and mathematical simulations reveal the capacity of geometric latches to enable, reduce or enhance variation of ultrafast movements in biological and synthetic systems.

Anomalous inapplicability of nacre-like architectures as impact-resistant templates in a wide range of impact velocities

Nacre is generally regarded as tough body armor, but it was often smashed by predators with a certain striking speed. Nacre-like architectures have been demonstrated to dissipate abundant energy by tablets sliding at static or specific low-speed loads, but whether they're still impact-resistant templates in a wide range of impact velocities remains unclear. Here, we find an anomalous phenomenon that nacre-like structures show superior energy-dissipation ability only in a narrow range of low impact velocities, while they exhibit lower impact resistance than laminated structures when impact velocity exceeds a critical value. This is because the tablets sliding in nacre-like structure occurs earlier and wider at low impact velocities, while it becomes localized at excessive impact velocities. Such anomalous phenomenon remains under different structural sizes and boundary conditions. It further inspires us to propose a hybrid architecture design strategy that achieves optimal impact resistance in a wide range of impact velocities.

Hybrid quadrature moment method for accurate and stable representation of non-Gaussian processes applied to bubble dynamics

Solving the population balance equation (PBE) for the dynamics of a dispersed phase coupled to a continuous fluid is expensive. Still, one can reduce the cost by representing the evolving particle density function in terms of its moments. In particular, quadrature-based moment methods (QBMMs) invert these moments with a quadrature rule, approximating the required statistics. QBMMs have been shown to accurately model sprays and soot with a relatively compact set of moments. However, significantly non-Gaussian processes such as bubble dynamics lead to numerical instabilities when extending their moment sets accordingly. We solve this problem by training a recurrent neural network (RNN) that adjusts the QBMM quadrature to evaluate unclosed moments with higher accuracy. The proposed method is tested on a simple model of bubbles oscillating in response to a temporally fluctuating pressure field. The approach decreases model-form error by a factor of 10 when compared with traditional QBMMs. It is both numerically stable and computationally efficient since it does not expand the baseline moment set. Additional quadrature points are also assessed, optimally placed and weighted according to an additional RNN. These points further decrease the error at low cost since the moment set is again unchanged. This article is part of the theme issue 'Data-driven prediction in dynamical systems'.

Engineered living bioassemblies for biomedical and functional material applications

Recent breakthroughs in biofabrication of bioasemblies, consisting of the engineered structures composed of biological or biosynthetic components into a single construct, have found a wide range of practical applications in medicine and engineering. This review presents an overview of how the bottom-up assembly of living entities could drive advances in medicine, by developing tunable biological models and more precise methods for quantifying biological events. Moreover, we delve into advances beyond biomedical applications, where bioassemblies can be manipulated as functional robots and construction materials. Finally, we address the potential challenges and opportunities in the field of engineering living bioassemblies, toward building new design principles for the next generation of bioengineering applications.

Padmavati. Reappearance of stomatopod Gonodactylus platysoma (Wood-Mason, 1895) after an era from the intertidal region of Chota Balu, South Andaman, India

Mantis Shrimp Gonodactylus platysoma was observed during a survey for seaweed-related macrofauna from the intertidal region of Andamans after a century. The specimen was collected using a scoop net, identified based on Kemp (1913) and Ahyong (2001). The detailed description, images and illustrations are given in this article. The reappearance of G. platysoma after a century highlights the potential of revealing the rich biodiversity in Andaman and the need to monitor stomatopods for a better overview of their ecological interactions and diversity.

The effect of thermally robust ballistic mechanisms on climatic niche in salamanders

Many organismal functions are temperature-dependent due to the contractile properties of muscle. Spring-based mechanisms offer a thermally robust alternative to temperature-sensitive muscular movements and may correspondingly expand a species’ climatic niche by partially decoupling the relationship between temperature and performance. Using the ballistic tongues of salamanders as a case study, we explore whether the thermal robustness of elastic feeding mechanisms increases climatic niche breadth, expands geographic range size, and alters the dynamics of niche evolution. Combining phylogenetic comparative methods with global climate data, we find that the feeding mechanism imparts no discernable signal on either climatic niche properties or the evolutionary dynamics of most climatic niche parameters. Although biomechanical innovation in feeding influences many features of whole-organism performance, it does not appear to drive macro-climatic niche evolution in salamanders. We recommend that future work incorporate micro-scale environmental data to better capture the conditions that salamanders experience, and we discuss a few outstanding questions in this regard. Overall, this study lays the groundwork for an investigation into the evolutionary relationships between climatic niche and biomechanical traits in ectotherms.

Complex Nanowrinkling in Chiral Liquid Crystal Surfaces: From Shaping Mechanisms to Geometric Statistics

Surface wrinkling is closely linked to a significant number of surface functionalities such as wetting, structural colour, tribology, frictions, biological growth and more. Given its ubiquity in nature’s surfaces and that most material formation processes are driven by self-assembly and self-organization and many are formed by fibrous composites or analogues of liquid crystals, in this work, we extend our previous theory and modeling work on in silico biomimicking nanowrinkling using chiral liquid crystal surface physics by including higher-order anisotropic surface tension nonlinearities. The modeling is based on a compact liquid crystal shape equation containing anisotropic capillary pressures, whose solution predicts a superposition of uniaxial, equibiaxial and biaxial egg carton surfaces with amplitudes dictated by material anchoring energy parameters and by the symmetry of the liquid crystal orientation field. The numerical solutions are validated by analytical solutions. The blending and interaction of egg carton surfaces create surface reliefs whose amplitudes depend on the highest nonlinearity and whose morphology depends on the anchoring coefficient ratio. Targeting specific wrinkling patterns is realized by selecting trajectories on an appropriate parametric space. Finally, given its importance in surface functionalities and applications, the geometric statistics of the patterns up to the fourth order are characterized and connected to the parametric anchoring energy space. We show how to minimize and/or maximize skewness and kurtosis by specific changes in the surface energy anisotropy. Taken together, this paper presents a theory and simulation platform for the design of nano-wrinkled surfaces with targeted surface roughness metrics generated by internal capillary pressures, of interest in the development of biomimetic multifunctional surfaces.

In situ determination of the extreme damage resistance behavior in stomatopod dactyl club

The structure and mechanical properties of the stomatopod dactyl club have been studied extensively for its extreme impact tolerance, but a systematic in situ investigation on the multiscale mechanical responses under high-speed impact has not been reported. Here the full dynamic deformation and crack evolution process within projectile-impacted dactyl using combined fast 2D X-ray imaging and high-resolution ex situ tomography are revealed. The results show that hydration states can lead to significantly different toughening mechanisms inside dactyl under dynamic loading. A previously unreported 3D interlocking structural design in the impact surface and impact region is reported using nano X-ray tomography. Experimental results and dynamic finite-element modeling suggest this unique structure plays an important role in resisting catastrophic structural damage and hindering crack propagation. This work is a contribution to understanding the key toughening strategies of biological materials and provides valuable information for biomimetic manufacturing of impact-resistant materials in general.

Functional Morphology of the Thorax of the Click Beetle Campsosternus auratus (Coleoptera, Elateridae), with an Emphasis on Its Jumping Mechanism

Simple Summary

Click beetles are well-known for the specialized thoracic structure, which they can click to thrust themselves into the air and to right themselves. Several aspects of their jumping mechanism were still not entirely clear prior to this study. We utilized traditional dissection, 3D virtual dissection, and high-speed filming techniques to investigate the functional morphology of their thorax. Our results show several new insights into their extraordinary clicking and jumping mechanisms.

Abstract

We investigated and described the thoracic structures, jumping mechanism, and promesothoracic interlocking mechanism of the click beetle Campsosternus auratus (Drury) (Elateridae: Dendrometrinae). Two experiments were conducted to reveal the critical muscles and sclerites involved in the jumping mechanism. They showed that M2 and M4 are essential clicking-related muscles. The prosternal process, the prosternal rest of the mesoventrite, the mesoventral cavity, the base of the elytra, and the posterodorsal evagination of the pronotum are critical clicking-related sclerites. The destruction of any of these muscles and sclerites resulted in the loss of normal clicking and jumping ability. The mesonotum was identified as a highly specialized saddle-shaped biological spring that can store elastic energy and release it abruptly. During the jumping process of C. auratus, M2 contracts to establish and latch the clicking system, and M4 contracts to generate energy. The specialized thoracic biological springs (e.g., the prosternum and mesonotum) and elastic cuticles store and abruptly release the colossal energy, which explosively raises the beetle body in a few milliseconds. The specialized trigger muscle for the release of the clicking was not found; our study supports the theory that the triggering of the clicking is due to the building-up of tension (i.e., elastic energy) in the system.

A novel power-amplified jumping behavior in larval beetles (Coleoptera: Laemophloeidae)

Larval insects use many methods for locomotion. Here we describe a previously unknown jumping behavior in a group of beetle larvae (Coleoptera: Laemophloeidae). We analyze and describe this behavior in Laemophloeus biguttatus and provide information on similar observations for another laemophloeid species, Placonotus testaceus. Laemophloeus biguttatus larvae precede jumps by arching their body while gripping the substrate with their legs over a period of 0.22 ± 0.17s. This is followed by a rapid ventral curling of the body after the larvae releases its grip that launches them into the air. Larvae reached takeoff velocities of 0.47 ± 0.15 m s-1 and traveled 11.2 ± 2.8 mm (1.98 ± 0.8 body lengths) horizontally and 7.9 ± 4.3 mm (1.5 ± 0.9 body lengths) vertically during their jumps. Conservative estimates of power output revealed that some but not all jumps can be explained by direct muscle power alone, suggesting Laemophloeus biguttatus may use a latch-mediated spring actuation mechanism (LaMSA) in which interaction between the larvae's legs and the substrate serves as the latch. MicroCT scans and SEM imaging of larvae did not reveal any notable modifications that would aid in jumping. Although more in-depth experiments could not be performed to test hypotheses on the function of these jumps, we posit that this behavior is used for rapid locomotion which is energetically more efficient than crawling the same distance to disperse from their ephemeral habitat. We also summarize and discuss jumping behaviors among insect larvae for additional context of this behavior in laemophloeid beetles.

Materials for Smart Soft Actuator Systems

In contrast to conventional hard actuators, soft actuators offer many vivid advantages, such as improved flexibility, adaptability, and reconfigurability, which are intrinsic to living systems. These properties make them particularly promising for different applications, including soft electronics, surgery, drug delivery, artificial organs, or prosthesis. The additional degree of freedom for soft actuatoric devices can be provided through the use of intelligent materials, which are able to change their structure, macroscopic properties, and shape under the influence of external signals. The use of such intelligent materials allows a substantial reduction of a device's size, which enables a number of applications that cannot be realized by externally powered systems. This review aims to provide an overview of the properties of intelligent synthetic and living/natural materials used for the fabrication of soft robotic devices. We discuss basic physical/chemical properties of the main kinds of materials (elastomers, gels, shape memory polymers and gels, liquid crystalline elastomers, semicrystalline ferroelectric polymers, gels and hydrogels, other swelling polymers, materials with volume change during melting/crystallization, materials with tunable mechanical properties, and living and naturally derived materials), how they are related to actuation and soft robotic application, and effects of micro/macro structures on shape transformation, fabrication methods, and we highlight selected applications.

Short-range hunters: exploring the function and constraints of water shooting in dwarf gouramis

Ballistic predation is a rare foraging adaptation: in fishes, most attention has focused on a single genus, the archerfish, known to manipulate water to shoot down prey above the water surface. However, several gourami species also exhibit apparently similar 'shooting' behaviour, spitting water up to 5 cm above the surface. In a series of experiments, we explored the shooting behaviour and aspects of its significance as a foraging ability in the dwarf gourami (Trichogaster lalius). We investigated sex differences in shooting abilities to determine whether gourami shooting is related to the sex-specific bubble nest manufacture where males mix air and water at the surface to form bubbles. We found that, actually, both sexes were equally able to shoot and could learn to shoot a novel target. In a second experiment, we presented untrained gouramis with opportunities to shoot at live prey and found they successfully shot down both fruit flies and crickets. Finally, we explored the effect of target height on shooting performance to establish potential constraints of shooting as a foraging ability. The frequency of attempted shots and success of hitting targets decreased with height, whereas latency to shoot increased. We also observed that repeatable individual differences account for variation in these measures of shooting performance. Together, our results provide evidence that gourami shooting has a foraging function analogous to that of archerfish. Gourami shooting may serve as an example of convergent evolution and provide opportunities for comparative studies into the, as yet unexplored, ecology and evolution of shooting in fishes.

Structure and mineralization of the spearing mantis shrimp (Stomatopoda; Lysiosquillina maculata) body and spike cuticles

Stomatopoda is a crustacean order including sophisticated predators called spearing and smashing mantis shrimps that are separated from the well-studied Eumalacotraca since the Devonian. The spearing mantis shrimp has developed a spiky dactyl capable of impaling fishes or crustaceans in a fraction of second. In this high velocity hunting technique, the spikes undergo an intense mechanical constraint to which their exoskeleton (or cuticle) has to be adapted. To better understand the spike cuticle internal architecture and composition, electron microscopy, X-ray microanalysis and Raman spectroscopy were used on the spikes of 7 individuals (collected in French Polynesia and Indonesia), but also on parts of the body cuticle that have less mechanical stress to bear. In the body cuticle, several specificities linked to the group were found, allowing to determine the basic structure from which the spike cuticle has evolved. Results also highlighted that the body cuticle of mantis shrimps could be a model close to the ancestral arthropod cuticle by the aspect of its biological layers (epi- and procuticle including exo- and endocuticle) as well as by the Ca-carbonate/phosphate mineral content of these layers. In contrast, the spike cuticle exhibits a deeply modified organization in four functional regions overprinted on the biological layers. Each of them has specific fibre arrangement or mineral content (fluorapatite, ACP or phosphate-rich Ca-carbonate) and is thought to assume specific mechanical roles, conferring appropriate properties on the entire spike. These results agree with an evolution of smashing mantis shrimps from primitive stabbing/spearing shrimps, and thus also allowed a better understanding of the structural modifications described in previous studies on the dactyl club of smashing mantis shrimps.

Bioinspired Bistable Dielectric Elastomer Actuators: Programmable Shapes and Application as Binary Valves

Nature has plenty of imitable examples of bistable thin structures that can actuate in response to mechanical and environmental stimuli, such as touch, light, and moisture. Scientists and engineers have used these as models to develop real-world systems with enhanced shape stability, energy efficiency, and power output. The bistable leaf of the Venus Flytrap (VFT) has a uniquely simple structure that enables exquisite actuation to trap the prey instantly. In this study, we present a strategy, inspired and derived from the VFT, which incorporates dielectric elastomer (DE) layers in a bistable actuator capable of reversible snapping through electrical stimulation. The trilayered laminated actuator is composed of two prestrained layers and a strain-limiting middle layer. The balance between elastic energy and bending energy of the laminates results in bistable shapes. We explore a broad design space of the bistable architecture through analysis and experiments to validate the fabrication parameters. The rapid snap-through between the two stable configurations is activated by a voltage pulse applied on the DE layers that change the laminate's strain field. Whereas a high electric field is used as the actuation trigger, the self-stabilization characteristic of the bistable structure obviates the need for continuous voltage supply. Finally, we recommended a new method of flow control by modulating porosity on curved surfaces through operating bistable dielectric elastomer actuators as binary valves.

The ultrafast snap of a finger is mediated by skin friction

The snap of a finger has been used as a form of communication and music for millennia across human cultures. However, a systematic analysis of the dynamics of this rapid motion has not yet been performed. Using high-speed imaging and force sensors, we analyse the dynamics of the finger snap. We discover that the finger snap achieves peak angular accelerations of 1.6 × 10⁶° s^-2 in 7 ms, making it one of the fastest recorded angular accelerations the human body produces (exceeding professional baseball pitches). Our analysis reveals the central role of skin friction in mediating the snap dynamics by acting as a latch to control the resulting high velocities and accelerations. We evaluate the role of this frictional latch experimentally, by covering the thumb and middle finger with different materials to produce different friction coefficients and varying compressibility. In doing so, we reveal that the compressible, frictional latch of the finger pads likely operates in a regime optimally tuned for both friction and compression. We also develop a soft, compressible friction-based latch-mediated spring actuated model to further elucidate the key role of friction and how it interacts with a compressible latch. Our mathematical model reveals that friction plays a dual role in the finger snap, both aiding in force loading and energy storage while hindering energy release. Our work reveals how friction between surfaces can be harnessed as a tunable latch system and provides design insight towards the frictional complexity in many robotic and ultra-fast energy-release structures.

Not So Fast: Strike Kinematics of the Araneoid Trap-Jaw Spider Pararchaea alba (Malkaridae: Pararchaeinae)

To capture prey otherwise unattainable by muscle function alone, some animal lineages have evolved movements that are driven by stored elastic energy, producing movements of remarkable speed and force. One such example that has evolved multiple times is a trap-jaw mechanism, in which the mouthparts of an animal are loaded with energy as they open to a wide gape and then, when triggered to close, produce a terrific force. Within the spiders (Araneae), this type of attack has thus far solely been documented in the palpimanoid family Mecysmaucheniidae but a similar morphology has also been observed in the distantly related araneoid subfamily Pararchaeinae, leading to speculation of a trap-jaw attack in that lineage as well. Here, using high-speed videography, we test whether cheliceral strike power output suggests elastic-driven movements in the pararchaeine Pararchaea alba. The strike speed attained places P. alba as a moderately fast striker exceeding the slowest mecysmaucheniids, but failing to the reach the most extreme high-speed strikers that have elastic-driven mechanisms. Using microcomputed tomography, we compare the morphology of P. alba chelicerae in the resting and open positions, and their related musculature, and based on results propose a mechanism for cheliceral strike function that includes a torque reversal latching mechanism. Similar to the distantly related trap-jaw mecysmaucheniid spiders, the unusual prosoma morphology in P. alba seemingly allows for highly maneuverable chelicerae with a much wider gape than typical spiders, suggesting that increasingly maneuverable joints coupled with a latching mechanism may serve as a precursor to elastic-driven movements.

The mitochondrial genome of Faughnia haani (Stomatopoda): novel organization of the control region and phylogenetic position of the superfamily Parasquilloidea

BACKGROUND

Stomatopod crustaceans are aggressive marine predators featuring complex compound eyes and powerful raptorial appendages used for "smashing" or "spearing" prey and/or competitors. Among them, parasquilloids (superfamily Parasquilloidea) possess eyes with 2-3 midband rows of hexagonal ommatidia and spearing appendages. Here, we assembled and analyzed the complete mitochondrial genome of the parasquilloid Faughnia haani and explored family- and superfamily-level phylogenetic relationships within the Stomatopoda based on mitochondrial protein coding genes (PCGs).

RESULTS

The mitochondrial genome of F. haani is 16,089 bp in length and encodes 13 protein coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes, and a control region that is relatively well organized, containing 2 GA-blocks, 4 poly-T stretches, various [TA(A)]n-blocks, and 2 hairpin structures. This organized control region is likely a synapomorphic characteristic in the Stomatopoda. Comparison of the control region among superfamilies shows that parasquilloid species are more similar to gonodactyloids than to squilloids and lysiosquilloids given the presence of various  poly-T stretches between the hairpin structures and [TA(A)]n-blocks. Synteny is identical to that reported for other stomatopods and corresponds to the Pancrustacea ground pattern. A maximum-likelihood phylogenetic tree based on PCGs revealed that Parasquilloidea is sister to Lysiosquilloidea and Gonodactyloidea and not to Squilloidea, contradicting previous phylogenetic studies.

CONCLUSIONS

The novel phylogenetic position of Parasquilloidea revealed by our study indicates that 'spearing' raptorial appendages are plesiomorphic and that the 'smashing' type is either derived (as reported in previous studies) or apomorphic. Our results raise the possibility that the spearing raptorial claw may have independently evolved twice. The superfamily Parasquilloidea exhibits a closer relationship with other stomatopod superfamilies with a different raptorial claw type and with dissimilar numbers of midband rows of hexagonal ommatidia. Additional studies focusing on the assembly of mitochondrial genomes from species belonging to different genera, families, and superfamilies within the order Stomatopoda are warranted to reach a robust conclusion regarding the evolutionary history of this iconic clade based on mitochondrial PCGs.

A physical model of mantis shrimp for exploring the dynamics of ultrafast systems

Efficient and effective generation of high-acceleration movement in biology requires a process to control energy flow and amplify mechanical power from power density-limited muscle. Until recently, this ability was exclusive to ultrafast, small organisms, and this process was largely ascribed to the high mechanical power density of small elastic recoil mechanisms. In several ultrafast organisms, linkages suddenly initiate rotation when they overcenter and reverse torque; this process mediates the release of stored elastic energy and enhances the mechanical power output of extremely fast, spring-actuated systems. Here we report the discovery of linkage dynamics and geometric latching that reveals how organisms and synthetic systems generate extremely high-acceleration, short-duration movements. Through synergistic analyses of mantis shrimp strikes, a synthetic mantis shrimp robot, and a dynamic mathematical model, we discover that linkages can exhibit distinct dynamic phases that control energy transfer from stored elastic energy to ultrafast movement. These design principles are embodied in a 1.5-g mantis shrimp scale mechanism capable of striking velocities over 26 m [Formula: see text] in air and 5 m [Formula: see text] in water. The physical, mathematical, and biological datasets establish latching mechanics with four temporal phases and identify a nondimensional performance metric to analyze potential energy transfer. These temporal phases enable control of an extreme cascade of mechanical power amplification. Linkage dynamics and temporal phase characteristics are easily adjusted through linkage design in robotic and mathematical systems and provide a framework to understand the function of linkages and latches in biological systems.

Study on the heterogeneous material coupling connection characteristics and mechanical strength of Oratosquilla oratoria mantis shrimp saddle

The microstructure, chemical composition and mechanical strength of heterogeneous materials of mantis shrimp (Oratosquilla oratoria) saddle were studied. As the key component of the striking system, the saddle comprised two distinct layers including outer layer and inner layer. The outer layer contained blocky microtubules and exhibited compact appearance. The inner layer presented a typical periodic lamellar structure. Due to the change of the thickness of the mineralized outer layer, the organic multilamellar structure became the foundation and enhanced the connection strength (4.55 MPa) at the connect regions between the saddle and merus exoskeleton and membrane, respectively. In the process of fracture, the lamellar structure dispersed the stress effectively by the change of the crack deflection direction and the microfibrils ordered arrangement. The exploration of mantis shrimp saddle region is beneficial to understand the striking system and provided the possibility for the stable connection of heterogeneous materials in engineering fields. The microstructure, heterogeneous material connection characteristics and high mechanical strength of saddle provide bionic models for the preparation of fiber-reinforced resin composites and soft composites.

Thermal sensitivity of Axolotl feeding behaviors

Musculoskeletal movement results from muscle contractions, recoil of elastic tendons, aponeuroses, and ligaments, or combinations thereof. Muscular and elastic contributions can vary both across behaviors and with changes in temperature. Skeletal muscles reach peak contraction speed at a temperature optimum with performance declining away from that optimum by approximately 50% per 10 °C, following the Q10 principle. Elastic recoil action, however, is less temperature sensitive. We subjected Axolotls (Ambystoma mexicanum) to changes from warm (23 °C), via medium (14 °C), to cold (6 °C) temperature across most of their thermal tolerance range, and recorded jaw kinematics during feeding on crickets. We sought to determine if suction feeding strikes and food processing chews involve elastic mechanisms and, specifically, if muscular versus elastic contribution vary with temperature for gape opening and closing. Measurements of peak and mean speed for gape opening and closing during strikes and chews across temperature treatments were compared to Q10-based predictions. We found that strike gape speed decreased significantly from warm and medium to cold treatments, indicating low thermal robustness, and no performance-enhancement due to elastic recoil. For chews, peak and mean gape closing speeds, as well as peak gape opening speed, also decreased significantly from warm to cold treatments. However, peak gape opening and closing speeds for chews showed performance-enhancement, consistent with a previously demonstrated presence of elastic action in the Axolotl jaw system. Our results add to a relatively small body of evidence suggesting that elastic recoil plays significant roles in aquatic vertebrate feeding systems, and in cyclic food processing mechanisms.

A review of linkage mechanisms in animal joints and related bioinspired designs

This paper presents a review of biological mechanical linkage mechanisms. One purpose is to identify the range of kinematic functions that they are able to perform. A second purpose is to review progress in bioinspired designs. Ten different linkage mechanisms are presented. They are chosen because they cover a wide range of functionality and because they have potential for bioinspired design. Linkage mechanisms enable animal joints to perform highly sophisticated and optimised motions. A key function of animal linkage mechanisms is the optimisation of actuator location and mechanical advantage. This is crucially important for animals where space is highly constrained. Many of the design features used by engineers in linkage mechanisms are seen in nature, such as short coupler links, extended bars, elastic energy storage and latch mechanisms. However, animal joints contain some features rarely seen in engineering such as integrated cam and linkage mechanisms, nonplanar four-bar mechanisms, resonant hinges and highly redundant actuators. The extreme performance of animal joints together with the unusual design features makes them an important area of investigation for bioinspired designs. Whilst there has been significant progress in bioinspiration, there is the potential for more, especially in robotics where compactness is a key design driver.

Multi-scale design of the chela of the hermit crab Coenobita brevimanus

The chela of the hermit crab protects its body against the attack from predators. Yet, a deep understanding of this mechanical defense is still lacking. Here, we investigate the chela of hermit crab, Coenobita brevimanus, and establish the relationships between the microstructures, chemical compositions and mechanical properties to gain insights into its biomechanical functions. We find that the chela is a multi-layered shell composed of five different layers with distinct features of the microstructures and chemical compositions, conferring different mechanical properties. Especially, an increase of the calcium carbonate content towards the layer furthest from the exterior, unlike the chemical gradients of many crustacean exoskeletons, provides a strong resistance to deformation. Nanoindentation measurements reveal that the overall gradient of the elastic modulus and hardness in the cross-section displays a sandwich profile, i.e., a soft core clamped by two stiff surface layers. Further mechanics modeling demonstrates that the high curvature and stiff innermost sublayer enhance the structural rigidity of the chela. In conjunction with the experimental observations, dynamic finite element analysis maps the time-spatial distribution of principal stress and indicates that fiber bridging might be the major mechanism against crack propagation at microscale. The lessons gained from the study of this multiphase biological composite could provide important insights into the design and fabrication of bioinspired materials for structural applications. STATEMENT OF SIGNIFICANCE: Multiple hierarchical structures have been discovered in a variety of exoskeletons. They are naturally designed to maintain the structural integrity and act as a protective layer for the animals. However, each kind of the hierarchical structures has its unique topology, chemical gradients as well as mechanical properties. We find that the chela is multi-layered shell composed of five different layers with distinct features of the microstructures and chemical compositions, conferring different mechanical properties. Especially, a large amount of helicoidal organic fibrils form highly organized 3D woven matrix in the innermost layer, providing a strong mechanical resistance to avoid catastrophic failure. The overall gradient of the elastic modulus and hardness in the cross-section display a sandwich profile, effectively minimizing the stress concentration and deformation. The lessons gained from the multiscale design strategy of the chela provide important insights into the design and fabrication of bioinspired materials.

Investigation of microstructure and dissimilar materials connection patterns of mantis shrimp saddle

The microstructure and dissimilar materials connection patterns of mantis shrimp saddle were investigated. The outer layer with layered helical structure and inner layer with slablike laminae structure constructed the microstructure characteristics of saddle. The merus and membrane were characterized by layered structure. The lamina of saddle connected the corresponding lamina in merus and membrane, building the continuous and smooth coupling connection patterns. The entitative "hard-hard" and "hard-soft" transitions of dissimilar materials at micro level enhanced the steady transmit of driven force. The saddle exhibited high mechanical strength. With the increase of in-situ tensile displacement, the number of fractured fragments on saddle outer layer surface increased, which subjected to tensile load and defused the damage in the form of mineralized surface fragmentation. In the inner part of saddle, the fracture of mineralized laminae and crack deflection mechanisms bore the tensile load influence. The combination of microstructure with high mechanical strength and continues micro lamina connection endowed the concise dissimilar materials connection and efficient elastic energy storage property of saddle, which can be treated as the bionic models for design and preparation of fiber reinforced resin composite, hyperelastic material and so on.

From Telson to Attack in Mantis Shrimp: Bridging Biomechanics and Behavior in Crustacean Contests

In the spirit of this symposium on the physical mechanisms of behavior, we review mantis shrimp ritualized fighting, from the telson to the attack, as an inspiring example of how the integration of biomechanics and behavioral research can yield a penetrating narrative for how animals accomplish important activities, including agonistic actions. Resolving conflicts with conspecifics over valuable resources is an essential task for animals, and this takes an unusual form in mantis shrimp due to their powerful raptorial appendages. Decades of field and laboratory research have provided key insights into the natural agonistic interactions of diverse mantis shrimp species, including how they use their raptorial weapons against one another in telson sparring matches over cavities. These insights provided the foundation for functional morphologists, biomechanists, and engineers to work through different levels of organization: from the kinematics of how the appendages move to the elastic mechanisms that power the strike, and down to the structure, composition, and material properties that transmit and protect against high-impact forces. Completing this narrative are studies on the defensive telson and how this structure is biomechanically matched to the weapon and the role it plays in ritualized fighting. The biomechanical understanding of the weapon and defense in mantis shrimp has, in turn, enabled a better understanding of whether mantis shrimp assess one another during contests and encouraged questions of evolutionary drivers on both the arsenal and behavior. Altogether, the body of research focused on mantis shrimp has presented perhaps the most comprehensive understanding of fighting, weapons, and defenses among crustaceans, from morphology and biomechanics to behavior and evolution. While this multi-level analysis of ritualized fighting in mantis shrimp is comprehensive, we implore the need to include additional levels of analysis to obtain a truly holistic understanding of this and other crustacean agonistic interactions. Specifically, both molting and environmental conditions are often missing from the narrative, yet they greatly affect crustacean weapons, defenses, and behavior. Applying this approach more broadly would generate a similarly profound understanding of how crustaceans carry out a variety of important tasks in diverse habitats.

Fracture toughness of the stomatopod dactyl club is enhanced by plastic dissipation: A fracture micromechanics study

The dactyl club of stomatopods is a biological hammer used to strike on hard-shell preys. To serve its function, the club must be imparted with a high tolerance against both contact stresses and fracture. While the contact mechanics of the club has been established, fracture toughness characterization has so far remained more elusive and semi-quantitative using nanoindentation fracture methods. Here, we used microcantilever fracture specimens with a chevron-notched crack geometry to quantitatively evaluate the fracture response of the impact region of dactyl clubs. The chevron-notched geometry was selected as it minimizes surface-related artefacts due to ion milling, and further allows to carry out fracture tests on samples free of pre-cracks with stable crack propagation even for brittle materials. Both linear elastic as well as elastic-plastic fracture mechanics methods, together with finite element modelling, were employed to analyse the fracture data. We find that crack-tip plastic dissipation is the main mechanism contributing to the fracture properties of the dactyl club material. Our study also suggests that the chevron-notched crack geometry is a suitable method to quantitatively assess the fracture toughness of hard biological materials. STATEMENT OF SIGNIFICANCE: Characterizing the fracture resistance of biomineralized structures is essential to draw their structure-properties relationships. Yet measuring the fracture properties of such materials is often hampered by their small size and irregular shape. Indentation fracture is used to circumvent these issues but does not discriminate between the elastic and elastic-plastic contributions to the fracture resistance. The dactyl club "hammer" of mantis shrimps is a biological material whose fracture properties are central to its function. A microfracture study was conducted using microcantilever specimens with chevron-notched crack geometry to assess the fracture toughness. Adopting linear elastic and elastic-plastic fracture mechanics protocols, we find that plastic dissipation is the major contribution to the fracture response of the hypermineralized impact region of the dactyl club.

Injuries in humans caused by mantis shrimp or siriboia (Crustacea: Stomatopoda)

INTRODUCTION:

Mantis shrimps or siriboias are crustaceans belonging to the order Stomatopoda. They are known for their strong claws, which they use for defense and capturing their prey. They are classified into two groups: the spearers, which pierce the prey with sharp projections, and the smashers, which strike their prey with high-powered punches. These animals are highly feared by fishermen, and there are frequent anecdotal reports of human injuries caused by these crustaceans.

METHODS:

A questionnaire about injuries in humans caused by these stomatopods was administered to 23 fishermen of Colony Z10 in Ubatuba, São Paulo state, Brazil, and a survey of the literature on injuries in humans caused by these animals was carried out.

RESULTS:

The fishermen consider the mantis shrimp dangerous and avoid direct contact with them on account of the associated risk. We describe five reports of human injuries caused by these animals: four by the claws and one by the tail spikes.

CONCLUSIONS:

We describe the first aid treatment, prevention, and recommendations for such cases and propose the distribution of educational leaflets among the fishermen colonies.

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 are of the same order of magnitude as for adults - even though adult appendages are up to two orders of magnitude longer. Larval strike speed (mean: 0.385 m s-1) exceeded the maximum swimming speed of similarly sized organisms from other species by several orders of magnitude. These findings establish the developmental timing and scaling of the mantis shrimp LaMSA mechanism and provide insights into the kinematic consequences of scaling limits in tiny elastic mechanisms.

Functional morphology of the raptorial forelegs in Mantispa styriaca (Insecta: Neuroptera)

The insect leg is a multifunctional device, varying tremendously in form and function within Insecta: from a common walking leg, to burrowing, swimming or jumping devices, up to spinning apparatuses or tools for prey capturing. Raptorial forelegs, as predatory striking and grasping devices, represent a prominent example for convergent evolution within insects showing strong morphological and behavioural adaptations for a lifestyle as an ambush predator. However, apart from praying mantises (Mantodea)—the most prominent example of this lifestyle—the knowledge on morphology, anatomy, and the functionality of insect raptorial forelegs, in general, is scarce. Here, we show a detailed morphological description of raptorial forelegs of Mantispa styriaca (Neuroptera), including musculature and the material composition in their cuticle; further, we will discuss the mechanism of the predatory strike. We could confirm all 15 muscles previously described for mantis lacewings, regarding extrinsic and intrinsic musculature, expanding it for one important new muscle—M24c. Combining the information from all of our results, we were able to identify a possible catapult mechanism (latch-mediated spring actuation system) as a driving force of the predatory strike, never proposed for mantis lacewings before. Our results lead to a better understanding of the biomechanical aspects of the predatory strike in Mantispidae. This study further represents a starting point for a comprehensive biomechanical investigation of the convergently evolved raptorial forelegs in insects.

The strike of the dragonfly larvae

The predatory strike of dragonfly larvae can inspire the design of fast robotic movement with enhanced control and precision.