scholarly journals Molting interferes with web decorating behavior in Argiope keyserlingi (Araneae, Araneidae)

2008 ◽  
Vol 36 (3) ◽  
pp. 538-544 ◽  
Author(s):  
André Walter ◽  
Mark A. Elgar ◽  
P. Bliss ◽  
Robin F. A. Moritz
Keyword(s):  
Argiope Keyserlingi

A natural history of web decorations in the St Andrew's Cross spider (Argiope keyserlingi)

2007 ◽  
Vol 55 (1) ◽  
pp. 9 ◽  
Author(s):  
Dinesh Rao ◽  
Ken Cheng ◽  
Marie E. Herberstein
Keyword(s):  
Natural History ◽  
Sustained Attention ◽  
Spider Webs ◽  
History Data ◽  
Web Spider ◽  
Exact Function ◽  
History Of ◽  
Argiope Keyserlingi ◽  
Orb Web ◽  
The Web

A long-running debate in the spider literature concerns the function of the extra silk decorations in some spider webs. These decorations are appended to the web and constitute a highly visible signal, which is inconsistent with the trend towards web invisibility. Despite the sustained attention of researchers, the exact function of these decorations is yet to be understood. While most studies have focussed on testing particular hypotheses, there has been a dearth of natural history data regarding web decorations in field conditions. In this study we present baseline data regarding the influence of seasonality, microhabitat characteristics and ecology on the presence of web decorations in an Australian orb web spider, Argiope keyserlingi. In particular, we show that there is preference among spiders to build their webs between bushes and to face the south-east, but this preference does not influence decoration building.

scholarly journals Investigating the transverse optical structure of spider silk micro-fibers using quantitative optical microscopy

Nanophotonics ◽  
2017 ◽  
Vol 6 (1) ◽  
pp. 341-348 ◽  
Author(s):  
Douglas J. Little ◽  
Deb M. Kane
Keyword(s):  
Refractive Index ◽  
Electromagnetic Scattering ◽  
Spider Silk ◽  
Transverse Optical ◽  
Graded Index ◽  
Argiope Keyserlingi ◽  
Wavelength Scale ◽  
Index Contrast ◽  
Spider Silks ◽  
Optical Structure

AbstractThe transverse optical structure of two orb-weaver (family Araneidae) spider dragline silks was investigated using a variant of the inverse-scattering technique. Immersing the silks in a closely refractive index-matched liquid, the minimum achievable image contrast was greater than expected for an optically homogeneous silk, given what is currently known about the optical absorption of these silks. This “excess contrast” indicated the presence of transverse optical structure within the spider silk. Applying electromagnetic scattering theory to a transparent double cylinder, the minimum achievable irradiance contrast for the Plebs eburnus and Argiope keyserlingi dragline silks was determined to be consistent with step index refractive index contrasts of 1−4×10−4 and 6–7×10−4, respectively, supposing outer-layer thicknesses consistent with previous TEM studies (50 nm and 100 nm, respectively). The possibility of graded index refractive index contrasts within the spider silks is also discussed. This is the strongest evidence, to date, that there is a refractive index contrast associated with the layered morphology of spider silks and/or variation of proportion of nanocrystalline components within the spider silk structure. The method is more generally applicable to optical micro-fibers, including those with refractive index variations on a sub-wavelength scale.

Foraging behaviour in orb-web spiders (Araneidae): do web decorations increase prey capture success in Argiope keyserlingi Karsch, 1878?

2000 ◽  
Vol 48 (2) ◽  
pp. 217 ◽  
Author(s):  
M. E. Herberstein
Keyword(s):  
Foraging Behaviour ◽  
Prey Capture ◽  
Paired Comparison ◽  
Mortality Rates ◽  
Argiope Keyserlingi ◽  
Orb Web ◽  
Orb Web Spiders ◽  
The Web ◽  
Web Size ◽  
Prey Attraction

Orb web spiders in the genus Argiope attach highly visible silk bands called decorations or stabilimenta to their webs. Two different hypotheses regarding the function of these structures were investigated in the field using Argiope keyserlingi: prey attraction and anti-predatory device. The first hypothesis suggests that web decorations attract prey to the web, and webs carrying decorations will capture more prey than those without. A field census of prey capture showed that webs adorned with more decorative bands indeed captured more but similarly sized prey per hour compared with webs carrying fewer decorations. Web height or web size, however, were not related to the rate of prey capture. This pattern was confirmed by a paired comparison of prey-capture rates within individuals that increased or decreased the number of decorative bands on consecutive days. Individuals that used more decorations also captured more prey compared with days when they spun fewer decorations. The second hypothesis suggests that these structures function as anti-predatory devices and, consequently, spiders on decorated webs benefit from a lower rate of mortality than spiders on undecorated webs. A census of the mortality rates of spiders over 19 days revealed that spiders did not disappear from undecorated webs more frequently than from decorated webs. Consequently, the idea that web decorations act as anti-predatory devices in A. keyserlingi was not supported.

Short and fast vs long and slow: age changes courtship in male orb-web spiders (Argiope keyserlingi)

2017 ◽  
Vol 105 (1-2) ◽  
Author(s):  
James C. O’Hanlon ◽  
Anne E. Wignall ◽  
Marie E. Herberstein
Keyword(s):  
Age Changes ◽  
Argiope Keyserlingi ◽  
Orb Web ◽  
Orb Web Spiders

Changes in male mate choice in a sexually cannibalistic orb-web spider (Araneae: Araneidae)

Behaviour ◽  
2004 ◽  
Vol 141 (10) ◽  
pp. 1197-1210 ◽  
Author(s):  
Mark Elgar ◽  
Anne Gaskett ◽  
Barbara Downes ◽  
Marie Herberstein
Keyword(s):  
Mate Choice ◽  
Field Experiments ◽  
Reproductive Status ◽  
Male Mating ◽  
Male Mate Choice ◽  
Mating History ◽  
Mating Opportunities ◽  
Argiope Keyserlingi ◽  
Orb Web ◽  
Male Mate

AbstractIn theory, male mate choice should occur when the costs of copulation, in terms of future mating opportunities, are high. The criteria males use to choose mates may change depending upon male mating history and the potential for future matings. We examine male mate choice in the St. Andrew's Cross Spider (Argiope keyserlingi Araneae: Araneidae). Laboratory experiments revealed that death and injury caused by female sexual cannibalism limits males to a maximum of two copulations. We assessed the mate choices of virgin and mated males for females of different reproductive status. We used field and laboratory choice bioassays involving airborne and web-based pheromones. In field experiments, wild males were strongly attracted to webs built by laboratory-raised virgin females. Webs from mated females did not attract males. Male mate choice was affected by male reproductive status: while virgin males strongly preferred penultimate and virgin females to mated females, mated males were apparently indifferent to females of different mating status. Such post-copulatory changes in male mate choice have not been previously documented, and may reflect a decreased potential for future mating.

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