Tuning the instrument: sonic properties in the spider's web

Abstract

Spider orb webs are multifunctional, acting to absorb prey impact energy and transmit vibratory information to the spider. This paper explores the links between silk material properties, propagation of vibrations within webs and the ability of the spider to control and balance web function. Combining experimental and modelling approaches, we contrast transverse and longitudinal wave propagation in the web. It emerged that both transverse and longitudinal wave amplitude in the web can be adjusted through changes in web tension and dragline silk stiffness, i.e. properties that can be controlled by the spider. In particular, we propose that dragline silk supercontraction may have evolved as a control mechanism for these multifunctional fibres. The various degrees of active influence on web engineering reveals the extraordinary ability of spiders to shape the physical properties of their self-made materials and architectures to affect biological functionality, balancing trade-offs between structural and sensory functions.

Detecting a Prey in a Spider Orb Web

“…Among other contributions, we mention the analysis of the role of aerody-namic drag in the dissipation of prey's energy and in reducing deterioration of the orb web by Zaera, Soler and Teus [21]; the key effect of the secondary frame in avoiding excessive stiffness in radial threads by Soler and Zaera [18]; the analysis of silk material properties and propagation of vibrations within webs by Mortimer, Soler, Siviour, Zaera and Vollrath [15]; the ability of the spider to adjust web pre-stress and dragline silk stiffness to tune both transverse and longitudinal wave propagation in the web [15]. Recently, Otto, Elias and Hatton [17] studied experimentally the dynamic response of artificial discrete spider webs, using frequency-based substructuring to determine frequency response functions of the system.…”

Web building and silk properties functionally covary among species of wolf spider

“…Unlike those of many web‐building spiders, wolf spider webs are devoid of sticky viscous silks and capture prey that falls rather than flies into it (Stefani & Del‐Claro, ). The web is predicted to be composed primarily of MA silk, which acts in both the capture of prey and, owing to its vibratory propagation capacity (Mortimer et al ., ), an extension of the spider's sensory system, thus enabling it to detect prey or other items that enter the web (see González et al ., and Eberhard & Hazzi, , for examples). Wolf spiders accordingly present as an excellent group for testing the above‐mentioned prediction wherever web‐building and non‐web‐building species might co‐exist (Blamires et al ., ).…”

Toward Computing with Spider Webs: Computational Setup Realization

“…The role of the spiral is to capture prey, benefiting from its sticky thread and large strain elasticity that creates a strong and effective snare, capable of capturing large prey relative to the web [4]. Typically, orb-weaving spiders have poor eyesight and in consequence are heavily dependent on (i) web vibrations, to provide information on current surroundings [4], and (ii) highly sensitive mechanoreceptors on all eight legs [5,6], which together enable the animal to interpret propagating web vibrations [7,8]. The structural [9,10] and vibration properties [5,11,12] of the spider web has been studied extensively .…”

“…The structural [9,10] and vibration properties [5,11,12] of the spider web has been studied extensively . Mortimer et al have recently studied and summarized the relevant research on the relationship between material properties of the web and its ability to transmit vibrations in experiments and finite element modeling, [7,8]. The following elements are proposed as control mechanisms that the spider employs in order to influence the structure sonic properties such as speed and amplitude [7,8]: super-contraction, web tensioning, and altering longitudinal (along with the threads), lateral (perpendicular to threads in web plan) and transverse (perpendicular to threads and web plan) vibrations.…”

“…There, the adopted definition for a morphological computation setup is discussed. The experimental procedure used by Mortimer et al [7,8] is explained. A mathematical lumped mass-spring-damper system model, similar to [9] by using the parameters in [7,8,11], is derived, as the theoretical part for a morphological computation setup.…”