Two notable examples are the Bolas Spiders ( Ordgarius), another moth specialist, and Net -casting Spiders ( Deinopis). These involve simplification and modification of the orb web and highly specialised web handling behaviour.
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In such elongate webs, moths lose so many scale hairs while struggling to get free that they become stuck before they can roll out of the web.Įven more specialised prey capture strategies have evolved in other descendants of orb weaver lineages.
However, some orb web weavers have evolved long, ladder-like orb webs. The body and wings of moths are covered in scale-like hairs that can be easily shed, and this often allows them to struggle free of a silk trap. For example, moths are a very abundant food source.
Many of these web builders use silk enswathing and wrapping to subdue and 'package' their meal for immediate or later consumption.ĭespite its great success as an insect trap, the orb web has undergone some interesting specialisations. These included 'space webs', 3-D webs with a maze of threads that delay the prey long enough for the spider to enswathe it in silk or bite it knockdown webs combining a maze of lines above with a silk sheet below - the maze of 'knockdown' threads stop flying or jumping prey which fall onto the sheet below and also help keep the sheet clear of debris orb webs, with large, planar catching surfaces that are sticky, strong and stretchy and virtually invisible to flying insects sticky 'gum-footed' webs like that of the Redback Spider that catch walking prey and many others. Insects provide the vast majority of spiders' food and many web-based prey catching strategies evolved in response to this plentitude. These webs are effective for capturing walking and jumping prey but will also entangle flying prey like moths and flies.
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By contrast, Hammock Web spiders sit on the rock or wood substrate shielded by their hammock-like sheet web. Most of these webs are built out from a crevice retreat in a soil bank or tree trunk. The common Black House or Window Spiders progressively thicken their sheet webs with several silk layers - the shawl-like webs. They are made by primitive cribellate spiders like the Tasmanian Cave Spider, Hickmania troglodytes, and many modern spiders like the striped sheet web spiders ( Therlinya spp). The ancestors of today's araneomorph spiders used cribellate (wool-like) catching silk, probably in some form of a simple sheet web, to capture their prey.
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