Control vs. Constraint: Understanding the Mechanisms of Vibration Transmission During Material-Bound Information Transfer

Abstract

Material-bound vibrations are ubiquitous in the environment and are widely used as an information source by animals, whether they are generated by biotic or abiotic sources. The process of vibration information transfer is subject to a wide range of physical constraints, especially during the vibration transmission phase. This is because vibrations must travel through materials in the environment and body of the animal before reaching embedded mechanosensors. Morphology therefore plays a key and often overlooked role in shaping information flow. Web-building spiders are ideal organisms for studying vibration information transfer due to the level of control they have over morphological traits, both within the web (environment) and body, which can give insights for bioinspired design. Here we investigate the mechanisms governing vibration information transfer, including the relative roles of constraints and control mechanisms. We review the known and theoretical contributions of morphological and behavioral traits to vibration transmission in these spiders, and propose an interdisciplinary framework for considering the effects of these traits from a biomechanical perspective. Whereas morphological traits act as a series of springs, dampers and masses arranged in a specific geometry to influence vibration transmission, behavioral traits influence these morphologies often over small timescales in response to changing conditions. We then explore the relative roles of constraints and control mechanisms in shaping the variation of these traits at various taxonomic levels. This analysis reveals the importance of morphology modification to gain control over vibration transmission to mitigate constraints and essentially promote information transfer. In particular, we hypothesize that morphological computation is used by spiders during vibration information transfer to reduce the amount of processing required by the central nervous system (CNS); a hypothesis that can be tested experimentally in the future. We can take inspiration from how spiders control vibration transmission and apply these insights to bioinspired engineering. In particular, the role of morphological computation for vibration control could open up potential developments for soft robots, which could use multi-scale vibration sensory systems inspired by spiders to quickly and efficiently adapt to changing environments.

Spider dynamics under vertical vibration and its implications for biological vibration sensing

“…This interaction within the whole spider system means that whole body spider dynamics need to be taken into account when understanding vibration sensing at any one part or leg. This supports the idea that the changing morphology, whether geometry or properties, will influence vibration sensing inputs into the nervous system, as a type of morphological computation [8]. In particular, our results suggest that the changes of biomechanical parameters in front and back legs can influence the leg responses more heavily compared to the middle legs.…”

“…Among them, spiders are arguably the vibration sensing experts in the animal kingdom, which enables them to detect prey, find mates and avoid predators effectively [5,6]. Understanding how spiders sense vibrations is helpful for developing innovative bioinspired technologies for use in engineering [7][8][9].…”

“…The vibration receptors of spiders are highly sensitive, capable of sensing external vibrational stimuli with amplitudes down to tens of nanometres [ 10 , 11 ]. Since spiders are found in diverse environments but have similar basic body plans, spiders are therefore good model organisms for studying vibration sensing [ 8 , 12 ]. The organs involved in mechanosensation, whether vibration sensing from external or internal sources, include slit sensilla, which act as detectors of strain of the spider's exoskeleton [ 13 ].…”

The type of leg lost affects habitat use but not survival in a non‐regenerating arthropod

“…Thus, sensory legs likely contribute more than locomotor legs to gathering information about the textural, mechanical, and chemical properties of the habitats. Consequently, losing sensory legs can negatively affect sensory exploration, as suggested for spiders (Miller & Mortimer, 2020). We hypothesize that harvestmen missing sensory legs may have a substantial sensory impairment that drives the changes in the selection of substrates we observed.…”

1/f laws found in non-human music

“…Vocalizations, restricted to vertebrates, originate in the respiratory system, while other sounds are produced mechanically by the interaction of body parts with themselves or the surrounding environment 23 . Sound reception of those signals in animals primarily entails mechanosensory organs responding to airborne signals, and vibratory (biotremological) sensing 24 . Our starting point is the hypothesis that across the diverse range of ways animals produce and perceive sounds 25 – 27 , there may be common organizing principles underlying all of these, and 1/ f β is such a candidate.…”