Decoding the locational information in the orb web vibrations ofAraneus diadematusandZygiella x-notata

Abstract

<jats:p>A spider's web is a multifunctional structure that captures prey and provides an information platform that transmits vibrational information. Many physical factors interact to influence web vibration and information content, from vibration source properties and input location, to web physical properties and geometry. The aim of the study was to test whether orb web vibration contains information about the location of the source of vibration. We used finite-element analysis model webs to control and vary major physical factors, investigating webs where spiders use a direct or remote monitoring strategy. When monitoring with eight sensors (legs) at the web centre, a comparison of longitudinal and transverse wave amplitude between the sensors gave sufficient information to determine source direction and distance, respectively. These localization cues were robust to changes in source amplitude, input angle and location, with increased accuracy at lower source amplitudes. When remotely monitoring the web using a single thread connected to the web's hub (a signal thread), we found that locational information was not available when the angle of the source input was unknown. Furthermore, a free sector and a stiff hub were physical mechanisms to aid information transfer, which provides insights for bioinspired fibre networks for sensing technologies.</jats:p>

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

“…There are also a few examples of where apparent physical constraints cause variation that may be harnessed for functional uses in the web. For example, although the spider body mass affects vibration transmission via mechanical impedance, this accentuates orientation cues in the web, which spiders may use to locate prey (Mortimer et al, 2019). As a final thought, few of the morphological traits we have reviewed appear to be free from any form of constraint, with the possible exception of mechanosensor placement.…”

“…However, some spiders may be able to use the mechanical impedance of their body mass functionally in vibration information transfer. This is because a mass at the hub alters both the speeds and amplitudes of vibrations in the web (Mortimer et al, 2018), which provide information on the location of a vibration source (Mortimer et al, 2019). Mechanical impedance of prey items may also be used by orb weavers as a prey localization cue (Mortimer et al, 2019).…”

Mechanosensation Mediates Long-Range Spatial Decision-Making in an Aneural Organism

“…Our discovery of mechanosensation in the unicellular slime mold underscores the early evolutionary origin of this computational modality (Cox et al, 2018). Interestingly, it is a truly multi-scale phenomenon, working not only at the level of single cells but also exploited by entire organisms, such as for example spiders that decode the vibrations in their webs to identify location of prey (Mortimer et al, 2019), analogously to the abilities of Physarum within its substrate.…”

Functional flexibility in a spider's Orb Web

“…We may assume that the spider orientates towards a prey by (i) comparing the difference in longitudinal wave amplitudes perceived via different radials and by (ii) estimating the distance to a prey from the ratio of peak transverse wave amplitudes perceived via different radials (Landolfa and Barth 1996;Mortimer et al 2018bMortimer et al , 2019Mortimer 2019).…”