scholarly journals The role of capture spiral silk properties in the diversification of orb webs

2012 ◽  
Vol 9 (77) ◽  
pp. 3240-3248 ◽  
Author(s):  
Anna Tarakanova ◽  
Markus J. Buehler
Keyword(s):  
Mechanical Properties ◽  
Prey Capture ◽  
Coarse Grained ◽  
Driving Factor ◽  
Web Performance ◽  
Spider Web ◽  
Orb Web ◽  
System Energy ◽  
Thread Strength

Among a myriad of spider web geometries, the orb web presents a fascinating, exquisite example in architecture and evolution. Orb webs can be divided into two categories according to the capture silk used in construction: cribellate orb webs (composed of pseudoflagelliform silk) coated with dry cribellate threads and ecribellate orb webs (composed of flagelliform silk fibres) coated by adhesive glue droplets. Cribellate capture silk is generally stronger but less-extensible than viscid capture silk, and a body of phylogenic evidence suggests that cribellate capture silk is more closely related to the ancestral form of capture spiral silk. Here, we use a coarse-grained web model to investigate how the mechanical properties of spiral capture silk affect the behaviour of the whole web, illustrating that more elastic capture spiral silk yields a decrease in web system energy absorption, suggesting that the function of the capture spiral shifted from prey capture to other structural roles. Additionally, we observe that in webs with more extensible capture silk, the effect of thread strength on web performance is reduced, indicating that thread elasticity is a dominant driving factor in web diversification.

Towards a Mechanical Model of Skin: Insights into Stratum Corneum Mechanical Properties from Hierarchical Models of Lipid Organisation

2004 ◽  
Vol 844 ◽  
Author(s):  
Brendan O'Malley ◽  
David J. Moore ◽  
Massimo Noro ◽  
Jamshed Anwar ◽  
Becky Notman ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stratum Corneum ◽  
Mechanical Model ◽  
The Body ◽  
Coarse Grained ◽  
Lipid Matrix ◽  
Lipid Species ◽  
Atomistic Models ◽  
Mesoscale Simulations

ABSTRACTThe stratum corneum (SC), the outermost layer of the skin, provides the body with a physiologically essential barrier to unregulated water loss and the influx of exogenous substances. Furthermore, the 10–20 micron thick SC, composed of overlapping protein-rich corneocytes surrounded by a heterogeneous multilamellar lipid matrix, displays tremendous mechanical cohesion and thermal integrity. To understand the contribution of these components to SC mechanical properties requires building a complete mechanical model of the skin. In this study we focus on modelling the hierarchical microstructure of the lipid phase and its relation to mechanical properties using a combination of atomistic and mesoscale simulations. The modelling approaches are parameterised with experimental data from FT-IR spectroscopy, X-ray scattering and, in the case of the mesoscale simulations, with detailed density profiles derived from atomic models. The atomistic models are used to probe the role of specific lipid species in maintaining the thermal and structural stability of the SC extracellular lipid matrix and to investigate the role of hydrogen bonding networks in SC lipid cohesion. Mesoscale models are used to investigate domain formation and lipid bilayer organisation on length and time scales inaccessible with atomistic models. These coarse grained models display transitions between ordered hexagonal gel phases and fluid phases, reproducing the experimentally observed ordering of the hydrophilic and hydrophobic regions.

scholarly journals Small behavioral adaptations enable more effective prey capture by producing 3D-structured spider threads

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Caroline C. F. Grannemann ◽  
Marco Meyer ◽  
Marian Reinhardt ◽  
Martín J. Ramírez ◽  
Marie E. Herberstein ◽  
...  
Keyword(s):  
Prey Capture ◽  
Behavioral Differences ◽  
Research Attention ◽  
Fiber Alignment ◽  
Web Performance ◽  
Behavioral Adaptations ◽  
Zigzag Pattern ◽  
Orb Web ◽  
The Impact ◽  
The Web

AbstractSpiders are known for producing specialized fibers. The radial orb-web, for example, contains tough silk used for the web frame and the capture spiral consists of elastic silk, able to stretch when prey impacts the web. In concert, silk proteins and web geometry affects the spider’s ability to capture prey. Both factors have received considerable research attention, but next to no attention has been paid to the influence of fiber processing on web performance. Cribellate spiders produce a complex fiber alignment as their capture threads. With a temporally controlled spinneret movement, they connect different fibers at specific points to each other. One of the most complex capture threads is produced by the southern house spider, Kukulcania hibernalis (Filistatidae). In contrast to the so far characterized linear threads of other cribellate spiders, K. hibernalis spins capture threads in a zigzag pattern due to a slightly altered spinneret movement. The resulting more complex fiber alignment increased the thread’s overall ability to restrain prey, probably by increasing the adhesion area as well as its extensibility. Kukulcania hibernalis' cribellate silk perfectly illustrates the impact of small behavioral differences on the thread assembly and, thus, of silk functionality.

Orb-web inclination in Uloboridae spiders: the role of microhabitat structure and prey capture

2016 ◽  
Vol 29 (5) ◽  
pp. 474-489 ◽  
Author(s):  
Suzana Diniz ◽  
João Vasconcellos-Neto ◽  
Vanessa Stefani
Keyword(s):  
Prey Capture ◽  
Orb Web ◽  
Microhabitat Structure

Mechanisms of Deformation Behavior of Coarse-Grained and Ultrafine-Grained Ti

2010 ◽  
Vol 667-669 ◽  
pp. 749-754
Author(s):  
Igor V. Alexandrov ◽  
Roza G. Chembarisova
Keyword(s):  
Mechanical Properties ◽  
Deformation Behavior ◽  
Coarse Grained ◽  
Dislocation Slip ◽  
Metallic Materials ◽  
Intensive Study ◽  
Deformation Method ◽  
Ultrafine Grained ◽  
Mechanisms Of Deformation

A grain size is known to be one of the factors which define mechanical properties of metallic materials. At the same time the mechanisms which regulate the deformation behavior of bulk ultrafine-grained (UFG) metals produced by the severe plastic deformation method are still a subject for intensive study and fixed ambiguously. The report presents the developed model and the results of its application for kinetic modeling of the deformation behavior of coarse-grained (CG) and UFG Ti. Modeling has been carried out considering the possible contribution of dislocation slip and ageing. Conclusions about the role of the investigated mechanisms in the appearance of the peculiarities of the deformation behavior of CG and UFG Ti have been made.

High-resolution images of cobweb threads of black widow spider Lactradectus mactans by Atomic-Force Microscopy

1994 ◽  
Vol 52 ◽  
pp. 1056-1057
Author(s):  
A. N. Nguyen ◽  
A. M. F. Moore ◽  
S. A. C. Gould
Keyword(s):  
Mechanical Properties ◽  
High Resolution ◽  
Structural Properties ◽  
Spider Silk ◽  
Black Widow ◽  
Black Widow Spider ◽  
Spider Web ◽  
Atomic Force ◽  
Orb Web ◽  
Widow Spider

Its unique mechanical properties make spider silk well-suited to the capture of prey. Orb webs capture prey by dissipating kinetic energy of prey; therefore, high strain and low resilience are important properties of the silk. Cobwebs capture prey with thread breakage and entanglement; therefore, other properties may be more important. Studies reveal that orb web silks consists of proteins arranged in anti-parallel beta sheets. X-ray diffractions reveal orderly crystal regions interspersed with amorphous regions. Silks of different functions from the same web consist of similar proportions of amino acids, yet differ significantly in mechanical properties. It has been suggested that the amorphous regions play a role in determining mechanical properties of spider web. Given these differences in types of orb web silk threads from a single web, we expect to find different structural properties in the cobweb. We present our progress in measuring the structural properties of the cobweb of the black widow spider, Lactradectus mactans, at the molecular level. Our initial results consist of high resolution atomic force microscope (AFM) images of the thread.

scholarly journals Sucker Rings from the Humboldt Squid Dosidicus gigas: The Role of Nanotubule Architecture on the Mechanical Properties

2009 ◽  
Vol 1187 ◽  
Author(s):  
Ali Miserez ◽  
James Weaver ◽  
David Kisailus ◽  
Henrik Birkedal
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Prey Capture ◽  
Dosidicus Gigas ◽  
Small Reduction ◽  
Data Support ◽  
Local Porosity ◽  
Prime Determinant ◽  
Humboldt Squid

AbstractThe suckers that line the arms and tentacles of squid are equipped with rigid toothed ring-like elements that increase the gripping power during prey capture and handling. The sucker rings of the Humboldt squid Dosidicus gigas, are fully proteinaceous and contain nanotubules with diameters ranging from 100 to 250 nm. It has been shown previously that the ensuing porosity is a prime determinant of the local elastic modulus [A. Miserez et al., Adv. Mater. <b>21</b>, 401 (2009)]. Here additional nanoindentation data are presented together with structural analyses. The nanomechanical data support our model that the measured modulus is determined by the local porosity. The dry moduli reach ca. 8 GPa and are reduced about two-fold in the hydrated state. This surprisingly small reduction is discussed in relation to possible chemistries responsible for assembly of these structures.

Adaptive flexibility in cues guiding spider web construction and its possible implications for spider cognition

Behaviour ◽  
2019 ◽  
Vol 156 (3-4) ◽  
pp. 331-362 ◽  
Author(s):  
William G. Eberhard
Keyword(s):  
Cognitive Processes ◽  
Prey Capture ◽  
Published Data ◽  
Substantial Variation ◽  
Spider Web ◽  
Learning Hypothesis ◽  
Orb Web ◽  
And Control ◽  
Web Construction

Abstract Orb web construction was originally thought to be highly stereotyped, but adaptive flexibility is now well established in several aspects. This study reviews published data on one behavioural cue and presents new data on flexibility in experimentally modified and control webs of Zosis geniculata and Uloborus diversus. By occasionally ignoring this cue temporarily, spiders gained access to otherwise inaccessible portions of their webs. I discuss three hypotheses concerning the mechanism that resulted in this flexibility. Several types of evidence argue against the hypothesis that the adjustments were pre-programmed: substantial variation in the contexts when adjustments occurred; substantial variation in details of the adjustments; and rarity of the contexts that require adjustments in nature. Lack of plausible links between behavioural decisions and payoffs from prey capture argue against a second, learning hypothesis. By elimination, this flexibility may require a third type of explanation that includes more elaborate cognitive processes.

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