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This is a really good question! Here is a quick skim over some research into spider silk and the evolution of web-building. (Silk) thread… https://twitter.com/barrygoldman1/status/1343659082675351552
Originally, spiders used silk as many other arthropods do—to wrap eggs, line burrows, etc. Spinnerets originated as modified appendages—think little mini-legs with silk glands in them. Spigots gave spiders more control over silk.
Selden 2008 https://www.pnas.org/content/105/52/20781
Selden 2008 https://www.pnas.org/content/105/52/20781
Many trapdoor spiders and tarantulas use threads of silk as "triplines" coming out from burrows that alert them to passing prey. See. eg, this @EmanueleBiggi photo ( https://www.naturepl.com/stock-photo-malaysian-trapdoor-spider-liphistius-malayanus--adult-female-in-her-image01592793.html)
(At first aerial webs were not needed, as flying insects had not evolved yet.)
(At first aerial webs were not needed, as flying insects had not evolved yet.)
At first spider silk used for capture webs was tangly/fuzzy, like Velcro on a nano-scale. How it works (Bott 2017): https://royalsocietypublishing.org/doi/10.1098/rspb.2017.0363
But sticky silk was much better for building aerial webs (Blackledge 2009 https://www.pnas.org/content/106/13/5229 , Wolff 2019 https://onlinelibrary.wiley.com/doi/abs/10.1111/evo.13834)
But sticky silk was much better for building aerial webs (Blackledge 2009 https://www.pnas.org/content/106/13/5229 , Wolff 2019 https://onlinelibrary.wiley.com/doi/abs/10.1111/evo.13834)
Amazingly, the classic "orb web" is one of the earliest forms, and aerial web-weaving spiders branched out from that.
" As insects took to flight, spiders chased up after them, placing their snares higher in the air." https://www.scientificamerican.com/article/sticky-science-the-evolution-of-spider-webs/ (re: Selden & Vollrath 2007)
" As insects took to flight, spiders chased up after them, placing their snares higher in the air." https://www.scientificamerican.com/article/sticky-science-the-evolution-of-spider-webs/ (re: Selden & Vollrath 2007)
This @bittelmethis piece for NatGeo is a great introduction to the diversity of spiderwebs: https://www.nationalgeographic.com/animals/2019/09/spiderwebs-explained/
We're still learning how spider silk turns from liquid to amazingly strong fibre: https://www.nytimes.com/2020/11/04/science/spider-silk-web-self-assembly.html (re Malay 2020 https://advances.sciencemag.org/content/6/45/eabb6030)
Lastly, why is there such a huge industry for manufacturing spider silk artificially, and how do we make it? Here's a piece by @BlackWidowJola: https://thebiologist.rsb.org.uk/news/news-archive/158-biologist/features/2358-futuristic-fibres
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