Talia Y. Moore

ABSTRACT Mammal tails have long been recognized for their diversity of morphological form and function, however, there remains a substantial gap between the motivation to understand and emulate the various performance functions of the tail and what is known about tail anatomy. In this study, we were motivated to discover the anatomical foundations of the fast, whipping motions of the tail of the lesser Egyptian jerboa ( Jaculus jaculus ), which may aid in the quick changes of direction as the animal escapes from predators using ricochetal bipedal hopping. We employed microCT scans, dissections, and museum data to describe the musculoskeletal anatomy of the jerboa in comparison with the laboratory mouse ( Mus musculus ) and rat ( Rattus norvegicus ). While many aspects of tail anatomy are conserved across these species, the jerboa does possess unique characteristics such as an extremely long tail arising from caudal vertebral elongation, development of extensive dorsal musculature differentiated into lateral and medial components to increase points of skeletal attachment, and a novel anatomical feature – the bi-lobed cranial transverse process – which serves as a supernumerary dorsal tendon attachment site and possible brace to protect the ventral tendons and intrinsic muscles for a section of caudal vertebrae which likely experiences high mechanical stress.

Envenomation is a complex process involving multi-physics interactions between the fang, the liquid venom, and the tissue of the target. Direct measurements of how fang shape modulates in-wound venom transport are scarce, as most studies isolate puncture performance or conduit hydrodynamics. It is widely assumed that tubular anterior fangs enable the most rapid, high-pressure delivery, but rigorous cross-type, standardized comparisons of delivery efficiency are limited. Here, we present the design and validation of Bite-Bot, a robotic platform designed to facilitate highly controlled experiments that intend to reveal the constituent and combined effects of evolutionary variation in the envenomer and the target tissue. First, we obtained uCT scans of snake fangs that varied in overall shape and venom delivery mechanism and 3D printed them in titanium. Our robot controls the angle of attack, speed, and force of the bite. The robot also injects our bespoke venom phantom, which matches the rheological properties of specific snake species, at a given pressure. By leveraging robotics, we can now more holistically and empirically study the complex physical interactions and the coevolution between the envenomer and the target tissue.

Robotic models of biological systems are useful for independently varying specific features to determine their contribution to whole-system behavior, but most quadrupedal robots differ so greatly from animal morphologies that they have minimal biomechanical relevance. Commercially available quadrupedal robots are also prohibitively expensive for biological research programs and difficult to customize. Here, we present a 3D printable, low-cost quadrupedal robot with modular legs that can match a wide range of animal morphologies for biomechanical hypothesis testing. The Robot Of Theseus (TROT) costs ≈$4000 to build out of 3D printed parts and standard off-the-shelf supplies. There are three main mechanisms to enhance morphological modularity: (1) each limb can consist of 3 or 4 rigid links, (2) the direction of the femur-tibia joint can be easily switched to mimic a knee or elbow, and (3) telescoping mechanisms allow users to vary the length of each limb link. The open-source software accommodates user-defined gaits and morphology changes. Effective leg length, or crouch, is determined by the four-bar linkage actuating each joint. The backdrivable motors can vary virtual spring stiffness and range of motion. Full descriptions of the TROT hardware and software are freely available online with assembly and user guides. We demonstrate the use of TROT to compare locomotion among extant, extinct, and theoretical morphologies. We found that a 29% percent increase in leg moment of inertia resulted in a 28.3% increase in cost of transport. In addition to biomechanical hypothesis testing, we envision a variety of different applications for this low-cost, modular, legged robotic platform, including developing novel control strategies, clearing land mines, or remote exploration. All CAD and code is available for download atwww.embirlab.com/trot.

We validated the use of an open-source computer vision toolkit to analyze high-quality behavioral data and evaluate welfare in the Lesser Egyptian Jerboa (Jaculus jaculus). Movements of these small, nocturnal rodents are rapid and difficult to observe, potentially obscuring behavioral assessment. However, assessment became warranted when alopecia and jumping were noted. We compared trained human observers to machine learning trained computer vision algorithms, evaluating accuracy and precision in behavioral classification. Human observers categorized behaviors with an overall accuracy of 0.71 ± 0.11 and an intraclass correlation coefficient (ICC) of 0.92 ± 0.07, with greater odds of misidentifying behaviors lasting less than one second. Computer vision classifiers successfully met human-grade accuracy and ICC, with significantly less sensitivity to behavioral duration. As 34% of manually classified behaviors lasted less than 0.5 seconds, we used computer vision to annotate activity budgets of captive jerboas before and after adding novel enrichment. Alopecia was significantly associated with grooming, and while grooming was negatively associated with terrarium height and with opaque dividers between terraria, conventional rodent enrichment had no significant effect on behavior. Inflammatory causes of alopecia were not found with cytologic, molecular, or histopathologic analysis. These results suggest captive jerboa may demonstrate psychogenic alopecia. Furthermore, computer vision automation allows for fast, accurate analysis of large volumes of behavioral data that can be used to tailor species-specific husbandry practices and improve animal welfare.

Abstract We validated the use of an open-source computer vision toolkit to analyze high-quality behavioral data and evaluate welfare in the Lesser Egyptian Jerboa ( Jaculus jaculus ). Movements of these small, nocturnal rodents are rapid and difficult to observe, potentially obscuring behavioral assessment. However, assessment became warranted when alopecia and jumping were noted. We compared trained human observers to machine learning trained computer vision algorithms, evaluating accuracy and precision in behavioral classification. Human observers categorized behaviors with an overall accuracy of 0.71 + 0.11 and an intraclass correlation coefficient (ICC) of 0.92 + 0.07, with greater odds of misidentifying behaviors lasting less than one second. Computer vision classifiers successfully met human-grade accuracy and ICC, with significantly less sensitivity to behavioral duration. As 34% of manually classified behaviors lasted less than 0.5 seconds, we used computer vision to annotate activity budgets of captive jerboas before and after adding novel enrichment. Alopecia was significantly associated with grooming, and while grooming was negatively associated with terrarium height and with opaque dividers between terraria, conventional rodent enrichment had no significant effect on behavior. Inflammatory causes of alopecia were not found with cytologic, molecular, or histopathologic analysis. These results suggest captive jerboa may demonstrate psychogenic alopecia. Furthermore, computer vision automation allows for fast, accurate analysis of large volumes of behavioral data that can be used to tailor species-specific husbandry practices and improve animal welfare.

In both animals and robots, locomotion capabilities are determined by the physical structure of the system. The majority of legged animals and robots are bilaterally symmetric, which facilitates locomotion with consistent headings and obstacle traversal, but leads to constraints in their turning ability. On the other hand, radially symmetric animals have demonstrated rapid turning abilities enabled by their omnidirectional body plans. Radially symmetric tripedal robots are able to turn instantaneously, but are commonly constrained by needing to change direction with every step, resulting in inefficient and less stable locomotion. Inspired by the radial symmetry and maneuverability of brittle stars and octopuses, we introduce a novel design for a tripedal robot that has both frictional and rolling contacts. Additionally, a freely rotating central sphere provides an added contact point so the robot can retain a stable tripod base of support while lifting and pushing with any one of its legs. The SKating, OmniOriented, Tripedal Robot (SKOOTR) is more versatile and stable than existing tripedal robots. It is capable of multiple forward gaits, multiple turning maneuvers, obstacle traversal, and stair climbing. SKOOTR has been designed to facilitate customization for diverse applications: it is fully open-source, is constructed with 3D printed or off-the-shelf parts, and costs approximately $ 500 USD to build. A project page with CAD files, assembly guide, and links to the github repository is posted at https://www.embirlab.com/skootr.

Robotic models are useful for independently varying specific features, but most quadrupedal robots differ so greatly from animal morphologies that they have minimal biomechanical relevance. Commercially available quadrupedal robots are also prohibitively expensive for biological research programs and difficult to customize. Here, we present a low-cost quadrupedal robot with modular legs that can match a wide range of animal morphologies for biomechanical hypothesis testing. The Robot Of Theseus (TROT) costs approximately $4000 to build out of 3D printed parts and standard off-the-shelf supplies. Each limb consists of 2 or 3 rigid links; the proximal joint can be rotated to become a knee or elbow. Telescoping mechanisms vary the length of each limb link. The open-source software accommodates user-defined gaits and morphology changes. Effective leg length, or crouch, is determined by the four-bar linkage actuating each joint. The backdrivable motors can vary virtual spring stiffness and range of motion. Full descriptions of the TROT hardware and software are freely available online. We demonstrate the use of TROT to compare locomotion among extant, extinct, and theoretical morphologies. In addition to biomechanical hypothesis testing, we envision a variety of different applications for this low-cost, modular, legged robotic platform, including developing novel control strategies, clearing land mines, or remote exploration. All CAD and code is available for download on the TROT project page.

Suction is a useful strategy to grasp objects or anchor a body, especially when prolonged contact is desired. For passive suction cups, detachment requires manual delamination, which cannot occur autonomously. Active suction cups detach via equalizing pressure in the suction cavity with the surrounding environment, either by adding fluid (e.g., from a compressed air source) or reducing the cavity volume. While this detachment mechanism can be autonomous, it is inefficient, resulting in a net zero or loss of fluid. A more efficient detachment mechanism would enable multiple iterations of attachment and detachment without requiring additional fluid. To address this need, we designed a suction cup with a secondary release chamber embedded in the contact ring. The release chamber triggers delamination by deforming the shape of the contact ring. Through empirical testing, we found the optimal location and geometry of the release chamber. Our design allows for reliable detachment with a 5 mL decrease in release chamber volume, regardless of the adhesive suction force. Because the release chamber is a closed system, attachment and detachment results in net gain of fluid. Therefore, we propose a novel secondary benefit of adhesion via suction: harvesting fluid to power other pressure-driven soft robotic systems.

Tails used as inertial appendages induce body rotations of animals and robots-a phenomenon that is governed largely by the ratio of the body and tail moments of inertia. However, vertebrate tails have more degrees of freedom (e.g., number of joints, rotational axes) than most current theoretical models and robotic tails. To understand how morphology affects inertial appendage function, we developed an optimization-based approach that finds the maximally effective tail trajectory and measures error from a target trajectory. For tails of equal total length and mass, increasing the number of equal-length joints increased the complexity of maximally effective tail motions. When we optimized the relative lengths of tail bones while keeping the total tail length, mass, and number of joints the same, this optimization-based approach found that the lengths match the pattern found in the tail bones of mammals specialized for inertial maneuvering. In both experiments, adding joints enhanced the performance of the inertial appendage, but with diminishing returns, largely due to the total control effort constraint. This optimization-based simulation can compare the maximum performance of diverse inertial appendages that dynamically vary in moment of inertia in 3D space, predict inertial capabilities from skeletal data, and inform the design of robotic inertial appendages.

Tails serve various functions in both robotics and biology, including expression, grasping, and defense. The vertebrate tails associated with these functions exhibit diverse patterns of vertebral lengths, but the precise mechanisms linking form to function have not yet been established. Vertebrate tails are complex musculoskeletal structures, making both direct experimentation and computational modeling challenging. This paper presents Tendon-Actuated Linked-Element (TALE), a modular robotic test bed to explore how tail morphology influences function. By varying 3D printed bones, silicone joints, and tendon configurations, TALE can match the morphology of extant, extinct, and even theoretical tails. We first characterized the stiffness of our joint design empirically and in simulation before testing the hypothesis that tails with different vertebral proportions curve differently. We then compared the maximum bending state of two common vertebrate proportions and one theoretical morphology. Uniform bending of joints with different vertebral proportions led to substantial differences in the location of the tail tip, suggesting a significant influence on overall tail function. Future studies can introduce more complex morphologies to establish the mechanisms of diverse tail functions. With this foundational knowledge, we will isolate the key features underlying tail function to inform the design for robotic tails. Images and videos can be found on TALE's project page: https://www.embirlab.com/tale.

The biological structures that fill the environment around us are derived from materials produced by organisms. These biological materials are key to the mechanical function of organisms. The pathways and growth processes that produce biological materials can influence the mechanical properties of the materials, which can in turn shape the higher level function of the system into which the materials are incorporated. Characterizing a biological system requires thorough knowledge of the underlying materials, including their mechanical function, diversity, evolution, and sensitivity to the environment. Anthropogenic activity is driving rapid and widespread changes to the natural environment and global climate, which are influencing organismal growth and physiology in myriad ways. Here, we briefly introduce a collection of articles that focus on the intersection of anthropogenic activity and the mechanical function of biological materials, as part of the "Global Change in a Material World" bundle for Integrative and Comparative Biology. In addition, we provide an analysis of the current scientific literature in this field, highlighting an urgent need to better understand how changes to our world, driven by human activity, are influencing the fundamental architecture and mechanical performance of organisms across the globe.

Computational models of musculoskeletal systems are essential tools for understanding how muscles, tendons, bones, and actuation signals generate motion. In particular, the OpenSim family of models has facilitated a wide range of studies on diverse human motions, clinical studies of gait, and even non-human locomotion. However, biological structures with many joints, such as fingers, necks, tails, and spines, have been a longstanding challenge to the OpenSim modeling community, especially because these structures comprise numerous bones and are frequently actuated by extrinsic muscles that span multiple joints-often more than three-and act through a complex network of branching tendons. Existing model building software, typically optimized for limb structures, makes it difficult to build OpenSim models that accurately reflect these intricacies. Here, we introduce ArborSim, customized software that efficiently creates musculoskeletal models of highly jointed structures and can build branched muscle-tendon architectures. We used ArborSim to construct toy models of articulated structures to determine which morphological features make a structure most sensitive to branching. By comparing the joint kinematics of models constructed with branched and parallel muscle-tendon units, we found that among various parameters-the number of tendon branches, the number of joints between branches, and the ratio of muscle fiber length to muscle tendon unit length-the number of tendon branches and the number of joints between branches are most sensitive to branching modeling method. Notably, the differences between these models showed no predictable pattern with increased complexity. As the proportion of muscle increased, the kinematic differences between branched and parallel models units also increased. Our findings suggest that stress and strain interactions between distal tendon branches and proximal tendon and muscle greatly affect the overall kinematics of a musculoskeletal system. By incorporating complex muscle-tendon branching into OpenSim models using ArborSim, we can gain deeper insight into the interactions between the axial and appendicular skeleton, model the evolution and function of diverse animal tails, and understand the mechanics of more complex motions and tasks.

Unionoid freshwater mussels (Bivalvia: Unionidae) are free-living apart from a brief, obligately parasitic, larval stage that infects fish hosts, and gravid female mussels have evolved a spectrum of strategies to infect fish hosts with their larvae. In many North American species, this involves displaying a mantle lure: a pigmented fleshy extension that acts as an aggressive mimic of a host fish prey, thereby eliciting a feeding response that results in host infection. The mantle lure of Lampsilis fasciola is of particular interest because it is apparently polymorphic, with two distinct primary lure phenotypes. One, described as “darter-like”, has “eyespots”, a mottled body coloration, prominent marginal extensions, and a distinct “tail”. The other, described as “worm-like”, lacks those features and has an orange and black coloration. We investigated this phenomenon using genomics, captive rearing, biogeographic, and behavioral analyses. Within-brood lure variation and within-population phylogenomic (ddRAD-seq) analyses of individuals bearing different lures confirmed that this phenomenon is a true polymorphism. The relative abundance of the two morphs appears stable over ecological timeframes: the ratio of the two lure phenotypes in a River Raisin (MI) population in 2017 was consistent with that of museum samples collected at the same site six decades earlier. Within the River Raisin, four main “darter-like” lure motifs visually approximated four co-occurring darter species ( Etheostoma blennioides, E. exile, E. microperca , and Percina maculata ), and the “worm-like” lure resembled a widespread common leech, Macrobdella decora . Darters and leeches are typical prey of Micropterus dolomieui (smallmouth bass), the primary fish host of L. fasciola . In situ field recordings of the L. fasciola “darter” and “leech” lure display behaviors, and the lure display of co-occurring congener L. cardium , were captured. Despite having putative models in distinct phyla, both L. fasciola lure morphs have largely similar display behaviors that differ significantly from that of sympatric L. cardium individuals. Some minor differences in the behavior between the two L. fasciola morphs were observed, but we found no clear evidence for a behavioral component of the polymorphism given the criteria measured. Discovery of discrete within-brood inheritance of the lure polymorphism implies potential control by a single genetic locus and identifies L. fasciola as a promising study system to identify regulatory genes controlling a key adaptive trait of freshwater mussels.

How should zoomorphic, or bio-inspired, robots indicate to humans that interactions will be safe and fun? Here, a survey is used to measure how human willingness to interact with a simulated butterfly robot is affected by different flight patterns. Flapping frequency, flap to glide ratio, and flapping pattern were independently varied based on a literature review of butterfly and moth flight. Human willingness to interact with these simulations and demographic information were self-reported via an online survey. Low flapping frequency and greater proportion of gliding were preferred, and prior experience with butterflies strongly predicted greater interaction willingness. The preferred flight parameters correspond to migrating butterfly flight patterns that are rarely directly observed by humans and do not correspond to the species that inspired the wing shape of the robot model. The most realistic butterfly simulations were among the least preferred. An analysis of animated butterflies in popular media revealed a convergence on slower, less realistic flight parameters. This iterative and interactive artistic process provides a model for determining human preferences and identifying functional requirements of robots for human interaction. Thus, the robotic design process can be streamlined by leveraging animated models and surveys prior to construction.

Soft robotic systems are promising for a wide range of applications from locomotion to manipulation. In particular, fluidic dielectric elastomer actuators, such as Hydraulically Amplified Self-healing ELectrostatic (HASEL) actuators, demonstrate several compelling properties when compared to other soft robotic actuators such as lower power consumption, faster response times, and self-sensing capabilities. Current HASEL actuator research has thoroughly characterized linear HASEL actuators, but there is a lack of geometric characterization for bending HASEL actuators. This paper addresses this gap through the characterization of two important design parameters that affect out-of-plane bending of planar HASEL actuator designs. In particular, a sinusoidal wave pattern is parameterized by the period length and the minimum channel width. The ratio of the period length to channel width is shown to be a good predictor for the curvature of the HASEL actuators when bending out-of-plane. The experimentally derived relationship is then used to demonstrate different grasp types for various objects.

In both animals and robots, locomotion capabilities are determined by the physical structure of the system. The majority of legged animals and robots are bilaterally symmetric, which facilitates locomotion with consistent headings and obstacle traversal, but leads to constraints in their turning ability. On the other hand, radially symmetric animals have demonstrated rapid turning abilities enabled by their omni-directional body plans. Radially symmetric tripedal robots are able to turn instantaneously, but are commonly constrained by needing to change direction with every step, resulting in inefficient and less stable locomotion. We address these challenges by introducing a novel design for a tripedal robot that has both frictional and rolling contacts. Additionally, a freely rotating central sphere provides an added contact point so the robot can retain a stable tripod base of support while lifting and pushing with any one of its legs. The SKating, Omni-Oriented, Tripedal Robot (SKOOTR) is more versatile and stable than other existing tripedal robots. It is capable of multiple forward gaits, multiple turning maneuvers, obstacle traversal, and stair climbing. SKOOTR has been designed to facilitate customization for diverse applications: it is fully open-source, is constructed with 3D printed or off-the-shelf parts, and costs approximately $500 USD to build.

Abstract Interactions between predator and prey are fundamental drivers of ecological and evolutionary dynamics. Behavioral responses are one of the most common strategies that prey species use to deter predation, especially through highly stereotyped defensive displays. However, these displays are also predicted to show strong context‐dependence, in which individuals can dynamically employ different display elements as a function of their own characteristics (e.g., age and sex) or those of the predator (e.g., type of predator). In this study, we experimentally tested for the effects of four simulated predator cues on defensive displays in two species of South American calico snakes (genus Oxyrhopus ). We found that juvenile snakes were both more likely to respond and to respond more strongly than adults and that displays were most common in response to tactile stimuli than to other treatments. However, we also found broad similarity across both simulated predator treatments and species in the components used in each snake's defensive display, suggesting a high degree of stereotyping. This research suggests an important role for both ontogeny and intensity of predation risk in structuring variation in defensive behavior in Neotropical snakes and emphasizes the foundational importance of context dependence in conceptual frameworks for understanding predator–prey interactions.

Abstract Computational models of musculoskeletal systems are essential tools for understanding how muscles, tendons, bones, and actuation signals generate motion. In particular, the OpenSim family of models has facilitated a wide range of studies on diverse human motions, clinical studies of gait, and even non-human locomotion. However, biological structures with many joints, such as fingers, necks, tails, and spines, have been a longstanding challenge to the OpenSim modeling community, especially because these structures comprise numerous bones and are frequently actuated by extrinsic muscles that span multiple joints—often more than three—and act through a complex network of branching tendons. Existing model building software, typically optimized for limb structures, makes it difficult to build OpenSim models that accurately reflect these intricacies. Here, we introduce ArborSim , customized software that efficiently creates musculoskeletal models of highly jointed structures and can build branched muscle-tendon architectures. We used ArborSim to construct toy models of articulated structures to determine which morphological features make a structure most sensitive to branching. By comparing the joint kinematics of models constructed with branched and parallel muscle-tendon units, we found that the number of tendon branches and the number of joints between branches are most sensitive to branching modeling method—notably, the differences between these models showed no predictable pattern with increased complexity. As the proportion of muscle increased, the kinematic differences between branched and parallel models units also increased. Our findings suggest that stress and strain interactions between distal tendon branches and proximal tendon and muscle greatly affect the overall kinematics of a musculoskeletal system. By incorporating complex muscle-tendon branching into OpenSim models using ArborSim , we can gain deeper insight into the interactions between the axial and appendicular skeleton, model the evolution and function of diverse animal tails, and understand the mechanics of more complex motions and tasks.

ABSTRACT Unionoid freshwater mussels (Bivalvia: Unionidae) are free-living apart from a brief, obligately parasitic, larval stage that infects fish hosts and gravid female mussels have evolved a spectrum of strategies to infect fish hosts with their larvae. In many North American species, this involves displaying a mantle lure: a pigmented fleshy extension that acts as an aggressive mimic of a host fish prey, thereby eliciting a feeding response that results in host infection. The mantle lure of Lampsilis fasciola is of particular interest because it is apparently polymorphic, with two distinct primary lure phenotypes. One, described as “darter-like”, has “eyespots”, a mottled body coloration, prominent marginal extensions, and a distinct “tail”. The other, described as “worm-like”, lacks those features and has an orange and black coloration. We investigated this phenomenon to 1) confirm that it is a true polymorphism; 2) investigate its ecological persistence; 3) identify the range of putative model species targeted by this mimicry system within a river drainage; 4) determine whether the mantle lure polymorphism includes a behavioral component. Detection of within-brood lure variation and within-population phylogenomic (ddRAD-seq) analyses of individuals bearing different lures confirmed that this phenomenon is a true polymorphism. It appears stable over ecological timeframes: the ratio of the two lure phenotypes in a River Raisin (MI) population in 2017 was consistent with that of museum samples collected at the same site 6 decades earlier. Within the River Raisin, four main “darter-like” lure motifs visually approximated four co-occurring darter species ( Etheostoma blennioides, E. exile, E. microperca, and Percina maculata ) and the “worm-like” lure resembled a widespread common leech, Macrobdella decora . Darters and leeches are typical prey of Micropterus dolomieui (smallmouth bass), the primary fish host of L. fasciola . In situ field recordings were made of the L. fasciola “darter” and “leech” lure display behaviors, in addition to the non-polymorphic lure display of co-occurring L. cardium . Despite having putative models in distinct phyla, both L. fasciola lure morphs have similar display behaviors that differ significantly from that of sympatric L. cardium individuals. We conclude that the L. fasciola mantle lure polymorphism does not include a behavioral component. Discovery of discrete within-brood inheritance of the lure polymorphism implies potential control by a single genetic locus and identifies L. fasciola as a promising study system to identify regulatory genes controlling a key adaptive trait of freshwater mussels.

Though they are compliant, nimble and morpho-logically intelligent, fluidic soft robots often rely on bulky components for power and actuation. This work contributes a design methodology which enables development of soft fluidic robots that move in a sequenced fashion, enabling lightweight devices with embodied intelligence. Bezier-curved beams were introduced as a design building block whose antagonistic placement results in Representative Auxetic Element (RAE) that can be patterned on inflatable shells. Kinematics and loading behaviour of these design building blocks were studied through Finite Element Analysis (FEA). We give a methodology for patterning RAEs on cylindrical and conic shells to create soft fluidic components that move (motion components) and those that delay fluid flow (pinch components). We verify the physical concepts governing the design methodology through two prototype devices that produce sequenced motion under a single fluidic input. Devices using this framework have the potential to perform complicated sequenced motions with lightweight control components.

Locomotor biomechanics faces a core trade-off between laboratory-based and field-based studies. Laboratory conditions offer control over confounding factors, repeatability, and reduced technological challenges, but limit the diversity of animals and environmental conditions that may influence behavior and locomotion. This article considers how study setting influences the selection of animals, behaviors and methodologies for studying animal motion. We highlight the benefits of both field- and laboratory-based studies and discuss how recent work leverages technological advances to blend these approaches. These studies have prompted other subfields of biology, namely evolutionary biology and ecology, to incorporate biomechanical metrics more relevant to survival in natural habitats. The concepts discussed in this Review provide guidance for blending methodological approaches and inform study design for both laboratory and field biomechanics. In this way, we hope to facilitate integrative studies that relate biomechanical performance to animal fitness, determine the effect of environmental factors on motion, and increase the relevance of biomechanics to other subfields of biology and robotics.