scholarly journals Spider webs inspiring soft robotics

2020 ◽  
Vol 17 (172) ◽  
pp. 20200569
Author(s):  
Fritz Vollrath ◽  
Thiemo Krink
Keyword(s):  
Decision Rules ◽  
Soft Robotics ◽  
Spider Webs ◽  
Complex Behaviour ◽  
Simple Rules ◽  
Rules Of Thumb ◽  
Orb Web ◽  
Orb Web Spiders ◽  
Novel Structures ◽  
Fine Tune

In soft robotics, bio-inspiration ranges from hard- to software. Orb web spiders provide excellent examples for both. Adapted sensors on their legs may use morphological computing to fine-tune feedback loops that supervise the handling and accurate placement of silk threads. The spider's webs embody the decision rules of a complex behaviour that relies on navigation and piloting laid down in silk by behaviour charting inherited rules. Analytical studies of real spiders allow the modelling of path-finding construction rules optimized in evolutionary algorithms. We propose that deconstructing spiders and unravelling webs may lead to adaptable robots able to invent and construct complex novel structures using relatively simple rules of thumb.

scholarly journals Dynamic environments do not appear to constrain spider web building behaviour

2021 ◽  
Vol 108 (3) ◽  
Author(s):  
Tom Mulder ◽  
Lucas Wilkins ◽  
Beth Mortimer ◽  
Fritz Vollrath
Keyword(s):  
Wind Loading ◽  
Spider Webs ◽  
Spider Web ◽  
Thread Tension ◽  
In The Wild ◽  
Orb Web ◽  
Araneus Diadematus ◽  
Orb Web Spiders ◽  
Building Behaviour ◽  
Web Building

AbstractMany laboratory experiments demonstrate how orb-web spiders change the architecture of their webs in response to prey, surroundings and wind loading. The overall shape of the web and a range of other web parameters are determined by frame and anchor threads. In the wild, unlike the lab, the anchor threads are attached to branches and leaves that are not stationary but move, which affects the thread tension field. Here we experimentally test the effect of a moving support structure on the construction behaviour and web-parameters of the garden cross spider Araneus diadematus. We found no significant differences in building behaviour between rigid and moving anchors in total time spent and total distance covered nor in the percentage of the total time spent and distance covered to build the three major web components: radials, auxiliary and capture spirals. Moreover, measured key parameters of web-geometry were equally unaffected. These results call for re-evaluation of common understanding of spider webs as thread tensions are often considered to be a major factor guiding the spider during construction and web-operation.

scholarly journals A novel property of spider silk: chemical defence against ants

2011 ◽  
Vol 279 (1734) ◽  
pp. 1824-1830 ◽  
Author(s):  
Shichang Zhang ◽  
Teck Hui Koh ◽  
Wee Khee Seah ◽  
Yee Hing Lai ◽  
Mark A. Elgar ◽  
...  
Keyword(s):  
Adaptive Response ◽  
Nutritional Value ◽  
Spider Silk ◽  
Chemical Defence ◽  
Spider Webs ◽  
Small Juvenile ◽  
Web Spider ◽  
Orb Web ◽  
Orb Web Spiders ◽  
The Web

Spider webs are made of silk, the properties of which ensure remarkable efficiency at capturing prey. However, remaining on, or near, the web exposes the resident spiders to many potential predators, such as ants. Surprisingly, ants are rarely reported foraging on the webs of orb-weaving spiders, despite the formidable capacity of ants to subdue prey and repel enemies, the diversity and abundance of orb-web spiders, and the nutritional value of the web and resident spider. We explain this paradox by reporting a novel property of the silk produced by the orb-web spider Nephila antipodiana (Walckenaer). These spiders deposit on the silk a pyrrolidine alkaloid (2-pyrrolidinone) that provides protection from ant invasion. Furthermore, the ontogenetic change in the production of 2-pyrrolidinone suggests that this compound represents an adaptive response to the threat of natural enemies, rather than a simple by-product of silk synthesis: while 2-pyrrolidinone occurs on the silk threads produced by adult and large juvenile spiders, it is absent on threads produced by small juvenile spiders, whose threads are sufficiently thin to be inaccessible to ants.

scholarly journals Do traders learn to select efficient market institutions?

2021 ◽  
Author(s):  
Carlos Alós-Ferrer ◽  
Johannes Buckenmaier ◽  
Georg Kirchsteiger
Keyword(s):  
Returns To Scale ◽  
Production Costs ◽  
Switching Behavior ◽  
Double Auction ◽  
Trading Behavior ◽  
Market Institutions ◽  
Market Institution ◽  
Simple Rules ◽  
Rules Of Thumb ◽  
Constant Returns To Scale

AbstractWhen alternative market institutions are available, traders have to decide both where and how much to trade. We conducted an experiment where traders decided first whether to trade in an (efficient) double-auction institution or in a posted-offers one (favoring sellers), and second how much to trade. When sellers face decreasing returns to scale (increasing production costs), fast coordination on the double-auction occurs, with the posted-offers institution becoming inactive. In contrast, under constant returns to scale, both institutions remain active and coordination is slower. The reason is that sellers trade off higher efficiency in a market with dwindling profits for biased-up profits in a market with vanishing customers. Hence, efficiency alone might not be sufficient to guarantee coordination on a single market institution if the surplus distribution is asymmetric. Trading behavior approaches equilibrium predictions (market clearing) within each institution, but switching behavior across institutions is explained by simple rules of thumb, with buyers chasing low prices and sellers considering both prices and trader ratios.

Web characteristics determine niche partitioning for orb-web spiders (Araneae, Tetragnathidae) in Malaysia

2017 ◽  
Vol 51 (3) ◽  
pp. 262-275 ◽  
Author(s):  
Dzulhelmi Muhammad Nasir ◽  
Thary Gazi Goh ◽  
Asraf Bakri ◽  
Faszly Rahim ◽  
Zulqarnain Mohamed ◽  
...  
Keyword(s):  
Niche Partitioning ◽  
Orb Web ◽  
Orb Web Spiders

scholarly journals Spiders did not repeatedly gain, but repeatedly lost, foraging webs

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6703 ◽  
Author(s):  
Jonathan A. Coddington ◽  
Ingi Agnarsson ◽  
Chris A. Hamilton ◽  
Jason E. Bond
Keyword(s):  
De Novo ◽  
Optimization Algorithms ◽  
Taxon Sampling ◽  
Spider Webs ◽  
Transcriptomic Data ◽  
Genomic Scale ◽  
Corrected Data ◽  
Orb Web ◽  
Coding Strategy ◽  
Phylogenetic Character

Much genomic-scale, especially transcriptomic, data on spider phylogeny has accumulated in the last few years. These data have recently been used to investigate the diverse architectures and the origin of spider webs, concluding that the ancestral spider spun no foraging web, that spider webs evolvedde novo10–14 times, and that the orb web evolved at least three times. These findings in fact result from a particular phylogenetic character coding strategy, specifically coding theabsenceof webs as logically equivalent, and homologous to, 10 other observable (i.e., not absent) web architectures. “Absence” of webs should be regarded as inapplicable data. To be analyzed properly by character optimization algorithms, it should be coded as “?” because these codes—or their equivalent—are handled differently by such algorithms. Additional problems include critical misspellings of taxon names from one analysis to the next (misspellings cause some optimization algorithms to drop terminals, which affects taxon sampling and results), and mistakes in spider natural history. In sum, the method causes character optimization algorithms to produce counter-intuitive results, and does not distinguish absence from secondary loss. Proper treatment of missing entries and corrected data instead imply that foraging webs are primitive for spiders and that webs have been lost ∼5–7 times, not gained 10–14 times. The orb web, specifically, may be homologous (originated only once) although lost 2–6 times.

scholarly journals Guiding lights: Foraging responses of juvenile nocturnal orb‐web spiders to the presence of artificial light at night

Ethology ◽  
2019 ◽  
Vol 125 (5) ◽  
pp. 289-297 ◽  
Author(s):  
Nikolas J. Willmott ◽  
Jessica Henneken ◽  
Mark A. Elgar ◽  
Therésa M. Jones
Keyword(s):  
Artificial Light ◽  
Light At Night ◽  
Orb Web ◽  
Orb Web Spiders

The silk tuft web decorations of the orb-weaver Gasteracantha cancriformis : testing the prey attraction and the web advertisement hypotheses

Behaviour ◽  
2008 ◽  
Vol 145 (3) ◽  
pp. 277-295 ◽  
Author(s):  
Felipe Gawryszewski ◽  
Paulo Motta
Keyword(s):  
Drosophila Melanogaster ◽  
Foraging Success ◽  
Uv Reflectance ◽  
Web Advertisement ◽  
Orb Web ◽  
Orb Web Spiders ◽  
Large Animals ◽  
And Control ◽  
The Web ◽  
Prey Attraction

AbstractSeveral orb-web spiders build conspicuous decorations in their webs. The prey attraction hypothesis proposes that decorations increase spider foraging success by attracting prey, and that attraction is linked to UV reflectance. Alternatively, the web advertisement hypothesis proposes that decorations are a signal that advertises the presence of the web to large animals. We tested both hypotheses for the web silk tufts of Gasteracantha cancriformis. Even though tufts are UV reflective, we did not find support for the prey attraction hypothesis. In the field, when webs with tufts painted black and control webs were compared, there were no differences in the number of prey captured, number of damaged areas in webs and type of prey captured. In the laboratory, Drosophila melanogaster did not demonstrate preference for tufted silk lines versus non-tufted silk lines. Our data also did not give support for the web advertisement hypothesis. The proportion of web destruction was similar between web with tufts painted black and control webs during four days of experimentation. Therefore, two of the most favoured hypotheses that attempt to explain decorations do not apply for web silk tufts in our study system. Instead we propose that silk tufts might be an aposematic signal.

Sensing opportunities in dynamic markets: how to encourage all employees to take part

2019 ◽  
Vol 40 (3) ◽  
pp. 18-24
Author(s):  
Klavdia Markelova Evans ◽  
Ashley Salaiz
Keyword(s):  
Design Methodology ◽  
Dynamic Capabilities ◽  
Dynamic Capability ◽  
Content Type ◽  
Dynamic Markets ◽  
Simple Rules ◽  
Rules Of Thumb ◽  
Micro Foundations ◽  
Practical Implications ◽  
Conceptual Work

Purpose This paper aims to investigate how companies can retain their ability to recognize, seize and maintain opportunities. Design/methodology/approach This conceptual work is built on existing research about an organization’s dynamic capabilities and literature on judgment under uncertainty. Findings This study offers specific ways in which companies can develop the dynamic capability of identifying new opportunities and, most importantly, how firms can maintain this rare dynamic capability for significant periods, so that they can harvest the benefits offered by owning this capability. Practical implications This study’s specific insights equip practitioners with turn-key information on how to build or maintain a firm’s unique ability to sense and capture an opportunity via the enhancement of the firm’s portfolio of simple rules. Originality/value This research introduces a novel idea about micro-foundations of a firm’s dynamic capabilities and theoretically argues that a favorable organizational culture and individuals’ rules of thumb can form a company’s dynamic ability to sense and seize an opportunity in high-velocity markets.

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