Adjustment of web-building initiation to high humidity: a constraint by humidity-dependent thread stickiness in the spider Cyrtarachne

Baba, Yasunori; Kusahara, Miki; Maezono, Yasunori; Miyashita, Tadashi

doi:10.1007/s00114-014-1196-9

Cited by 15 publications

(18 citation statements)

References 32 publications

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“…For example, spiders use glue-coated viscid threads, which are functionally analogous to glow-worm capture threads, to entrap prey in their webs (Blackledge, Kuntner & Agnarsson, 2011;Foelix, 2011). These silks can remain sticky in variable environments but seem to be optimized for certain humidity levels (Opell et al, 2013;Baba et al, 2014;Amarpuri et al, 2015). Several species of Cyrtarachne spiders, specialized moth-catching orb web weavers, and Tetragnatha laboriosa, orb web spiders that live near water, require very high humidity (100% RH) or face a three-to sevenfold decrease in stickiness (Baba et al, 2014;Amarpuri et al, 2015).…”

Section: Capture Thread Adhesionmentioning

confidence: 99%

“…By comparison, spider glue utilizes organic and inorganic salts to uptake and maintain atmospheric water, which facilitates dissolution and spreading of adhesive glycoproteins Amarpuri et al, 2015). The gluey silk of several species of orb web spiders appears to have adhesive properties that are optimized for the specific native humidity within their natural habitats (Opell, Karinshak & Sigler, 2013;Baba et al, 2014;Amarpuri et al, 2015). While the specific chemical composition of Arachnocampa capture glue likely differs from that of spider glue (Von Byern et al, 2016), it is possible that their adhesive performance is optimized to the high humidity (90-100% RH) of its native cave or wet forest environment.…”

Section: Introductionmentioning

confidence: 99%

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Humidity‐dependent mechanical and adhesive properties of Arachnocampa tasmaniensis capture threads

et al. 2018

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Bioluminescent glow‐worms (Arachnocampa spp.) capture prey in glue‐coated silk capture threads hung from their nests on damp cave and wet forest substrates. In a dry environment, these animals are very susceptible to desiccation as their bodies can become life threateningly dry and their silk has been anecdotally observed to become non‐sticky. Water has a plasticizing effect on the structural proteins of several invertebrate silks, including those used in caddisfly nets, mussel byssus and spider webs. Moreover, water facilitates interfacial adhesion by spreading adhesive biomolecules in functionally analogous velvet worm slime and spider silk glue. We tested the effects of water on the mechanics and adhesion of Arachnocampa tasmaniensis capture threads sampled within damp caves. We found that threads tested at high humidity were three times more compliant and over 10‐fold more extensible than those tested at low humidity (30% RH). We also found the threads to be significantly more adhesive in high humidity with force at detachment increasing two orders of magnitude and work of adhesion increasing by five orders of magnitude compared to threads tested at low humidity. Our results unequivocally demonstrate that A. tasmaniensis capture thread functionality is dependent upon exposure to high humidity. Our results both confirm previous reports and indicate that the foraging habitat of these animals is restricted to caves and cave‐like environments, such as wet forests.

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Section: Capture Thread Adhesionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Humidity‐dependent mechanical and adhesive properties of Arachnocampa tasmaniensis capture threads

et al. 2018

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“…Different species of spiders forage in diverse habitats, ranging from dry to humid, and aggregate glue adhesion is humidity-responsive such that adhesion is maximized for a given species at humidity matching its preferred microhabitat 12 . Some species that forage in wet habitats like Tetragnatha 12 and Cyrtarachne 13 produce aggregate glue that consistently adheres better at humidities exceeding 90% RH, contrary to most synthetic adhesives 1 , 2 . Even the aggregate glue from species found in dry habitats shows cohesive failure, instead of interfacial failure, at high humidity 12 .…”

Section: Introductionmentioning

confidence: 99%

Hygroscopic compounds in spider aggregate glue remove interfacial water to maintain adhesion in humid conditions

et al. 2018

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Adhesion in humid environments is fundamentally challenging because of the presence of interfacial bound water. Spiders often hunt in wet habitats and overcome this challenge using sticky aggregate glue droplets whose adhesion is resistant to interfacial failure under humid conditions. The mechanism by which spider aggregate glue avoids interfacial failure in humid environments is still unknown. Here, we investigate the mechanism of aggregate glue adhesion by using interface-sensitive spectroscopy in conjunction with infrared spectroscopy. We demonstrate that glycoproteins act as primary binding agents at the interface. As humidity increases, we observe reversible changes in the interfacial secondary structure of glycoproteins. Surprisingly, we do not observe liquid-like water at the interface, even though liquid-like water increases inside the bulk with increasing humidity. We hypothesize that the hygroscopic compounds in aggregate glue sequester interfacial water. Using hygroscopic compounds to sequester interfacial water provides a novel design principle for developing water-resistant synthetic adhesives.

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“…Spiders were housed in one of three sizes of plastic cages—height × length × width—27 × 17 × 16 cm, 20 × 20 × 20 cm, or 37 × 24 × 21 cm. Cyrtarachne require high humidity to induce web spinning (Miyashita, ; Baba, Kusahara, Maezono, & Miyashita, ), and so cages were designed similarly to those used to house Pasilobus , a sister clade that also builds similar webs only at high humidity (Miyashita, Kasada, & Tanikawa, ). The floor of each tank was layered with damp towels and filled with approximately 8 cm of water.…”

Section: Methodsmentioning

confidence: 99%

Silk structure rather than tensile mechanics explains web performance in the moth‐specialized spider, Cyrtarachne

Díaz

Tanikawa²,

Miyashita³

et al. 2018

J Exp Zool Pt A

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Orb webs intercept and retain prey so spiders may subdue them. Orb webs are composed of sticky, compliant spirals of capture silk spun across strong, stiff major ampullate silk threads. Interplay between differences in the mechanical properties of these silks is crucial for prey capture. Most orb webs depend upon insects contacting several radial and capture threads for successful retention. Moths, however, escape quickly from most orb webs due to the sacrificial scales covering their bodies. Cyrtarachne orb webs are unusual as they contain a reduced number of capture threads and moths stick unusually well to single threads. We aimed to determine how the tensile properties of the capture spiral and radial threads spun by Cyrtarachne operate in retention of moth prey. A NanoBionix UTM was used to quantify the material properties of flagelliform and major ampullate threads to test if Cyrtarachne's reduced web architecture is accompanied by improvements in tensile performance of its silk. Silk threads showed tensile properties typical of less-specialized orb-weavers, with the exception of high extensibility in radial threads. Radial thread diameters were 62.5% smaller than flagelliform threads, where commonly the two are roughly similar. We utilized our tensile data to create a finite element model of Cyrtarachne's web to investigate energy dissipation during prey impact. Large cross-sectional area of the flagelliform threads played a key role in enabling single capture threads to withstand prey impact. Rather than extraordinary silk, Cyrtarachne utilizes structural changes in the size and attachment of silk threads to facilitate web function.

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Adjustment of web-building initiation to high humidity: a constraint by humidity-dependent thread stickiness in the spider Cyrtarachne

Cited by 15 publications

References 32 publications

Humidity‐dependent mechanical and adhesive properties of Arachnocampa tasmaniensis capture threads

Humidity‐dependent mechanical and adhesive properties of Arachnocampa tasmaniensis capture threads

Hygroscopic compounds in spider aggregate glue remove interfacial water to maintain adhesion in humid conditions

Silk structure rather than tensile mechanics explains web performance in the moth‐specialized spider, Cyrtarachne

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