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Hackled Orbweavers and Net-casting Spiders Superfamily: Uloboroidea
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The Superfamily: Uloboroidea consists of a mere two, seemingly unrelated, families of spiders that both produce orb-webs - like the Araneoidea - but both of the two families have vastly different means of using the web. The Family: Uloboridae uses the web in the same classic manner as other Orb-weavers by suspending it vertically between fixed points. The Family: Deinopidae however, spins a simple orb-web web between the tips of the four frontlegs and then uses it as a net to cast over its' prey when it comes in range. What sets them apart from other other orb-weaving spiders, and therefore in their own superfamily, is the type of silk they use for the web. Uloboroidea are cribellate spiders whereas the Aranoid Spiders are mostly ecribellate.
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The distinction is in whether or not the spider has a cribellum, (literally: 'little sieve') the presence of which allows for the production of thousands of extremely fine threads of silk that are combed together using the spiders' calamistrum - a comb-like structure on each of the rear legs - to form a woolly kind of silk that by its' very nature is adhesive without using additional glue. Ecribellate spiders do not have a cribellum and they produce thicker strands of silk that is itself more like a thick, sticky liquid. It is generally accepted that all spiders were initially cribellate, but that, over time, many species lost the function during the course of evolution. Nowadays, many spider families contain a mix of both cribellate and ecribellate species.
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Uloboroid spiders occur worldwide in temperate to tropical areas but they do not tolerate extremes in temperatures so are absent from both arctic and desert areas. In Australia some species may be found all year round but, overall thay are most common from spring to autumn. All together there are 22 genera spread between the two constituent families with a total of 353 species although the Family: Uloboridae claims about 80% of these.
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References and links:
> Bott, R.A., Baumgartner, W.B., Braunig, P., Menzel, F. and Joel, A.-C.. (2017). 'Adhesion enhancement of cribellate capture threads by epicuticular waxes of the insect prey sheds new light on spider web evolution.' Proceedings of the Royal Society B. 31 May 2017. doi:10.1098/rspb.2017.0363
> Elettro, H., Neukirch, S., Antkowiak, A. and Vollrath, F., (2015). 'Adhesion of dry and wet cribellate silk.' The Science Of Nature, 102(7):1–4 (2015)
> Kono, N., Nakamura, H., Mori, M., Tomita, M. and , Arakawa, K., (2020). 'Spidroin profiling of cribellate spiders provides insight into the evolution of spider prey capture strategies.' Sci Rep. 2020 Sep 24;10(1):15721. doi: 10.1038/s41598-020-72888-6. PMID: 32973264; PMCID: PMC7515903.
https://en.wikipedia.org/wiki/Calamistrum
https://en.wikipedia.org/wiki/Cribellum
https://hebetslab.unl.edu/portfolio-posts/cribellate-vs-ecribellate-silk/
https://ucanr.edu/blogs/bugsquad/index.cfm?tagname=spider%20silk
> Bott, R.A., Baumgartner, W.B., Braunig, P., Menzel, F. and Joel, A.-C.. (2017). 'Adhesion enhancement of cribellate capture threads by epicuticular waxes of the insect prey sheds new light on spider web evolution.' Proceedings of the Royal Society B. 31 May 2017. doi:10.1098/rspb.2017.0363
> Elettro, H., Neukirch, S., Antkowiak, A. and Vollrath, F., (2015). 'Adhesion of dry and wet cribellate silk.' The Science Of Nature, 102(7):1–4 (2015)
> Kono, N., Nakamura, H., Mori, M., Tomita, M. and , Arakawa, K., (2020). 'Spidroin profiling of cribellate spiders provides insight into the evolution of spider prey capture strategies.' Sci Rep. 2020 Sep 24;10(1):15721. doi: 10.1038/s41598-020-72888-6. PMID: 32973264; PMCID: PMC7515903.
https://en.wikipedia.org/wiki/Calamistrum
https://en.wikipedia.org/wiki/Cribellum
https://hebetslab.unl.edu/portfolio-posts/cribellate-vs-ecribellate-silk/
https://ucanr.edu/blogs/bugsquad/index.cfm?tagname=spider%20silk
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