Omer Yuval

Subterranean locomotion challenges animals to maintain orientation and efficiently navigate confined spaces where vision is limited and local geometry is uncertain. Mole crickets (Gryllotalpidae), which regularly travel through self-excavated tunnels, provide a useful model for studying mechanosensory control of locomotion under these conditions. We hypothesized that backward walking, a prominent component of the mole cricket’s behavioral repertoire, is supported by complementary tactile input from the antennae and cerci. Adult Gryllotalpa tali were filmed while walking forward and backward in a narrow, straight tunnel arena under red light using high-speed video. Markerless pose tracking was used to quantify antennal and cercal tip movements, orientations, and wall-contact events in body and arena coordinates. Backward walking produced clear changes in tactile sampling behavior: antennae were reoriented and extended more posteriorly, while lateral cercal movements increased sensory coverage and posterior tactile input. Wall-contact monitoring suggested more frequent touching during backward locomotion by the antennae. These findings indicate that mole crickets adaptively reorganize active and passive mechanosensory sampling when moving backward, potentially improving boundary detection, stabilizing body posture, negotiating tunnel constraints, and supporting locomotion-related decision making during locomotion in tunnels.

Animal locomotion emerges from the complex interplay of morphology, neural control, and biomechanics, involving both active and passive elements. Insects have attracted much interest, and a rich ecosystem of computational models exists for insect locomotion. However, while active control mechanisms have been extensively studied, obtaining accurate and useful models remains challenging due to limited understanding of how detailed anatomical constraints and passive biomechanical properties shape movement. To address this, we developed anatomically accurate 3D models of the adult desert locust and mole cricket, two orthopteran insects that share a basic body plan but exhibit strikingly different morphologies linked to their habitats and specialized locomotor behaviors—jumping in locusts versus subterranean digging in mole crickets. We fine-tuned these models using precise morphometric measurements for each major body segment. Furthermore, we quantified passive joint dynamics through high-speed videography of anesthetized locust, revealing a two-phase return motion and history-dependent resting angles. By integrating these biologically grounded constraints into physical simulations, we significantly narrowed the parameter space, resulting in more realistic simulations. Our approach provides new tools for predicting biologically relevant, yet experimentally challenging variables, such as joint torques and contact forces, which contribute directly to the understanding of the underlying biological phenomena. Moreover, these improved simulations offer valuable insight for designing energy-efficient soft robotic systems.

Animals must make decisions about how to move through their environment to find food, shelter and mates, yet the general principles underpinning effective search strategies remain poorly understood. Exploration patterns, such as alternating intensive local search with long-range relocation, are observed across many species, but whether these reflect universal organising principles, or are simply imposed by structured environments, is an open question. Here, we reconstruct hours of Caenorhabditis elegans foraging in homogeneous three-dimensional volumes and show that this animal achieves optimal volumetric coverage using a hierarchical search strategy of quasi-planar locomotion patches punctuated by costlier volumetric reorientations. We propose that underlying this cost hierarchy is the worm’s highly-constrained shape-space and show that despite being spanned by only five body-posture modes, it gives rise to effective locomotion, combining non-planar gaits, planar turns and three-dimensional reorientation manoeuvres. Our finding that action frequencies decay with inferred cost in a Boltzmann-like distribution is consistent with the Principle of Maximum Entropy: optimal search emerging from the tendency to maximise information gained subject to embodied constraints. This general principle offers a unifying framework to assess the optimality of animal decision-making, with implications for understanding nervous system function, foraging ecology, and the physics of living active matter.

Insects are exceptionally robust walkers. Although different species exhibit distinct anatomical and functional specializations, they are also highly adaptive within these constraints. How such adaptations enable insects to efficiently navigate diverse environments and perform mechanical tasks remains far from fully explored. The mole cricket, which dwells underground, has been little studied to date, largely due to its cryptic lifestyle. It excels at digging tunnels and exhibits extreme morphological adaptations, particularly its exceptional fossorial forelegs. Its versatile locomotion, above and below ground, makes the mole cricket an attractive model system for studying the biomechanics of insect movement. Here we provide the first quantitative characterization of mole cricket locomotion. Using a tunnel-like arena, we video monitored insects and analyzed their locomotion gaits. We identified and described three main modes of locomotion, including a new, recently described backward-bound gait. To test specific hypotheses regarding form-function relationships and the generation of thrust, we integrated biomechanical modeling and deep reinforcement learning to simulate the observed gaits. Our work opens several future directions, from exploring context-dependent gait transitions to bio-inspired technological innovations.

Animal locomotion emerges from the complex interplay of morphology, neural control, and biomechanics, involving both active and passive elements. Insect have attracted much interest, and a rich ecosystem of computational models exists for insect locomotion. However, while active control mechanisms have been extensively studied, obtaining accurate and useful models remains challenging due to limited understanding of how detailed anatomical constraints and passive biomechanical properties shape movement. To address this, we developed anatomically accurate 3D models of the adult desert locust and mole cricket, two orthopteran insects that share a basic body plan but exhibit strikingly different morphologies linked to their habitats and specialized locomotor behaviors — jumping in locusts versus subterranean digging in mole crickets. We fine-tuned these models using precise morphometric measurements for each major body segment. Furthermore, we quantified passive joint dynamics through high-speed videography of anesthetized locust, revealing a two-phase return motion and history-dependent resting angles. By integrating these biologically grounded constraints into physical simulations, we significantly narrowed the parameter space, resulting in more realistic simulations. Our approach provides new tools for predicting biologically relevant, yet experimentally challenging variables, such as joint torques and contact forces, which contribute directly to the understanding of the underlying biological phenomena. Moreover, these improved simulations offer valuable insight for designing energy-efficient soft robotic systems.

Locomotor behaviour is a hallmark of animal biology and ecology. Mole crickets constitute a unique group of subterranean insects that present extreme morphological and behavioural adaptations. They therefore present a valuable model for locomotion-related research. Despite their remarkable leg-morphology adaptations, mole crickets mostly demonstrate the common insect double-tripod gait for locomotion. Here we report, however, that in response to an aversive stimulus from the front, the mole cricket will consistently adopt a unique backwards gait that we have termed ‘backward-bound’. Our temporal and spatial analysis shows that this previously unreported six-legged gait comprises a cyclic alternation between the middle and hind-leg pairs with rarely observed (in insects) left–right in-phase synchronization, while the front legs display noisy and less-consistent phase dynamics. This exceptional gait is transient and is replaced by regular backwards walking after several cycles. It is employed to distance the animal quickly from danger. A gait that can be characterized as ‘forward-bound’ is also displayed by the mole cricket, albeit for a much shorter duration (up to two cycles).

Complex dendritic trees are a distinctive feature of neurons. Alterations to dendritic morphology are associated with developmental, behavioral and neurodegenerative changes. The highly-arborized PVD neuron of C. elegans serves as a model to study dendritic patterning; however, quantitative, objective and automated analyses of PVD morphology are missing. Here, we present a method for neuronal feature extraction, based on deep-learning and fitting algorithms. The extracted neuronal architecture is represented by a database of structural elements for abstracted analysis. We obtain excellent automatic tracing of PVD trees and uncover that dendritic junctions are unevenly distributed. Surprisingly, these junctions are three-way-symmetrical on average, while dendritic processes are arranged orthogonally. We quantify the effect of mutation in git-1, a regulator of dendritic spine formation, on PVD morphology and discover a localized reduction in junctions. Our findings shed new light on PVD architecture, demonstrating the effectiveness of our objective analyses of dendritic morphology and suggest molecular control mechanisms.

Inhibition plays important roles in modulating the neural activities of sensory and motor systems at different levels from synapses to brain regions. To achieve coordinated movement, motor systems produce alternating contractions of antagonist muscles, whether along the body axis or within and among limbs, which often involves direct or indirect cross-inhibitory pathways. In the nematodeCaenorhabditis elegans, a small network involving excitatory cholinergic and inhibitory GABAergic motoneurons generates the dorsoventral alternation of body-wall muscles that supports undulatory locomotion. Inhibition has been suggested to be necessary for backward undulation because mutants that are defective in GABA transmission exhibit a shrinking phenotype in response to a harsh touch to the head, whereas wild-type animals produce a backward escape response. Here, we demonstrate that the shrinking phenotype is exhibited by wild-type as well as mutant animals in response to harsh touch to the head or tail, but only GABA transmission mutants show slow locomotion after stimulation. Impairment of GABA transmission, either genetically or optogenetically, induces lower undulation frequency and lower translocation speed during crawling and swimming in both directions. The activity patterns of GABAergic motoneurons are different during low-frequency and high-frequency undulation. During low-frequency undulation, GABAergic VD and DD motoneurons show correlated activity patterns, while during high-frequency undulation, their activity alternates. The experimental results suggest at least three non-mutually exclusive roles for inhibition that could underlie fast undulatory locomotion inC. elegans, which we tested with computational models: cross-inhibition or disinhibition of body-wall muscles, or neuronal reset.