Possible functional significance of spigot placement on the spinnerets of spiders

Eberhard, William G.

doi:10.1636/b09-97.1

Cited by 42 publications

(55 citation statements)

References 22 publications

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“…Draglines play a role in protecting the spider against unpredicted falls (Ortlepp and Gosline, 2008), controlling jumps (Chen et al, 2013) and on-water locomotion (Gorb and Barth, 1994), assisting navigation in webs (Barth et al, 1998), as elemental structures for webs (Denny, 1976), egg sac suspension (Gheysens et al, 2005), shelter building and intraspecific and interspecific communication (Leonard and Morse, 2006;Tietjen, 1977). Hence, a deviation from the usual ALS configuration (single large MA and an array of multiple small PI spigots) is extremely rare among araneomorph spiders (Coddington, 1989;Coddington and Levi, 1991;Eberhard, 2010;Murphy and Roberts, 2015). Although many (but not all) gnaphosids live on the ground and do not build webs, the reduced functionality of attachment discs may represent a significant draw-back, especially for the security of locomotion through a structured terrain, and the stability of shelters and egg sacs, all of which may potentially increase vulnerability to predation.…”

Section: Consequences Of the Functional Shiftmentioning

confidence: 99%

“…The most conspicuous characteristic is a strong modification of the spinning apparatus. Among araneomorph spiders, the first pair of spinnerets (ALS, anterior lateral spinnerets) usually bears the openings of single large major ampullate (MA) glands and numerous tiny piriform (PI) glands (Eberhard, 2010). The MA silk produces the main structural thread, the dragline, and from the PI glands short glue-coated micro-fibres emerge that fasten the dragline to substrates (Apstein, 1889;Wolff et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…The MA silk produces the main structural thread, the dragline, and from the PI glands short glue-coated micro-fibres emerge that fasten the dragline to substrates (Apstein, 1889;Wolff et al, 2015). This configuration is extremely conserved among araneomorph spiders, presumably because it is the basis for a versatile application of silk (Coddington, 1989;Coddington and Levi, 1991;Eberhard, 2010;Murphy and Roberts, 2015). However, in the Gnaphosidae, this configuration is strongly derived.…”

Section: Introductionmentioning

confidence: 99%

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Hunting with sticky tape: functional shift in silk glands of araneophagous ground spiders (Gnaphosidae)

Wolff

Řezáč

Krejčí

et al. 2017

Journal of Experimental Biology

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Foraging is one of the main evolutionary driving forces shaping the phenotype of organisms. In predators, a significant, though understudied, cost of foraging is the risk of being injured by struggling prey. Hunting spiders that feed on dangerous prey like ants or other spiders are an extreme example of dangerous feeding, risking their own life over a meal. Here, we describe an intriguing example of the use of attachment silk ( piriform silk) for prey immobilization that comes with the costs of reduced silk anchorage function, increased piriform silk production and additional modifications of the extrusion structures (spigots) to prevent their clogging. We show that the piriform silk of gnaphosids is very stretchy and tough, which is an outstanding feat for a functional glue. This is gained by the combination of an elastic central fibre and a bi-layered glue coat consisting of aligned nanofibrils. This represents the first tensile test data on the ubiquitous piriform gland silk, adding an important puzzle piece to the mechanical catalogue of silken products in spiders.

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Section: Consequences Of the Functional Shiftmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hunting with sticky tape: functional shift in silk glands of araneophagous ground spiders (Gnaphosidae)

Wolff

Řezáč

Krejčí

et al. 2017

Journal of Experimental Biology

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“…The architecture of silk anchorages is determined by the movement of the spinnerets during the spinning process, which follows a distinct choreography (Eberhard, ; Wolff, ; Wolff & Herberstein, ; Wolff, van der Meijden, & Herberstein, ). These spinning patterns define the orientation of the piriform fibres within the disc and the overall structure of the dragline joint.…”

Section: Discussionmentioning

confidence: 99%

“…Amongst these different silks, spiders use the secretion of the piriform glands to agglutinate silk fibres and securely cement their dragline to surfaces in distinct patterns that are called attachment discs (Schütt, ). Attachment discs are formed by quick alternating movements of the spinnerets forming a bilateral symmetric network of piriform fibres that enclose the dragline and spread on the target substrate (Eberhard, ; Grawe, Wolff, & Gorb, ; Wolff, ; Wolff & Herberstein, ). As the glue‐coated piriform silk provides remarkably strong adhesion on various surfaces, attachment discs are potentially interesting models for technical application and the development of anchoring systems (Grawe et al, ; Wolff, ).…”

Section: Introductionmentioning

confidence: 99%

Ultrastructure of spider thread anchorages

Wirth

Wolff

Appel

et al. 2019

Journal of Morphology

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Spiders attach silken threads to substrates by means of glue‐coated nanofibers (piriform silk), spun into disc‐like structures. The organization and ultrastructure of this nano‐composite silk are largely unknown, despite their implications for the biomechanical function and material properties of thread anchorages. In this work, the ultrastructure of silken attachment discs was studied in representatives of four spider families with Transmission Electron Microscopy to facilitate a mechanistic understanding of piriform silk function across spiders. Based on previous findings from comparative studies of piriform silk gland morphology, we hypothesized that the fibre‐glue proportion of piriform silk differs in different spiders, while the composition of fibre and glue fractions is consistent. Results confirmed large differences in the relative proportion of glue with low amounts in the orb weaver Nephila senegalensis (Araneidae) and the hunting spider Cupiennius salei (Ctenidae), larger amounts in the cobweb spider Parasteatoda tepidariorum (Theridiidae) and a complete reduction of the fibrous component in the haplogyne spider Pholcus phalangioides (Pholcidae). We rejected our hypothesis that glue ultrastructure is consistent. The glue is a colloid with polymeric and fluid fractions that strongly differ in proportions and assembly. We further confirmed that in all species studied both dragline and piriform silk fibres do not make contact with the environmental substrate. Instead, adhesion is established by a thin dense skin layer of the piriform glue. These results advance our understanding of piriform silk function and the interspecific variation of its properties, which is significant for spider biology, web function and the bioengineering of silk.

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Silk fibers and silk‐producing organs ofHarpactea rubicunda(C. L. Koch 1838) (Araneae, Dysderidae)

Hajer¹,

Malý²,

Řeháková³

2012

Microscopy Res & Technique

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Scanning electron microscopy and atomic force microscopy were used to study the silk spinning apparatus and silks of Harpactea rubicunda spiders. Three types of silk secretions that are produced by three kinds of silk spinning glands (ampullate, piriform, and pseudaciniform) and released through three types of spigots, were confirmed for both adult and juvenile spiders. Silk secretions for the construction of spider webs for shelter or retreat are produced by the pseudaciniform silk glands. Silk secretions that are released from spigots in the course of web construction are not processed by the legs during the subsequent process of hardening. Pairs of nanofibril bundles seemed to be part of the basic microarchitecture of the web silk fibers as revealed by AFM. These fiber bundles frequently not only overlap one another, but occasionally also interweave. This structural variability may strengthen the spider web. High-resolution AFM scans of individual nanofibrils show a distinctly segmented nanostructure. Each globular segment is ∼30-40 nm long along the longitudinal axis of the fiber, and resembles a nanosegment of artificial fibroin described by Perez-Rigueiro et al. (2007).

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Possible functional significance of spigot placement on the spinnerets of spiders

Cited by 42 publications

References 22 publications

Hunting with sticky tape: functional shift in silk glands of araneophagous ground spiders (Gnaphosidae)

Hunting with sticky tape: functional shift in silk glands of araneophagous ground spiders (Gnaphosidae)

Ultrastructure of spider thread anchorages

Silk fibers and silk‐producing organs ofHarpactea rubicunda(C. L. Koch 1838) (Araneae, Dysderidae)

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