Featherlegged Orbweaver Spider - Uloborus glomosus
Class: Arachnida / Order: Araneae / Family: Uloboridae (Cribellate Orb Weavers)
Uliboridae is the only family of spiders that do not posess venom glands. [1]
Live adult spiders photographed in the wild at San Antonio, Texas, USA.

Spiders in the family Uloboridae are commonly called cribellate orb weavers. Rather than relying on sticky silk to trap prey, the Uloboridae silk entraps insects by entangling their legs. The special silk is pulled from a field of very fine set of spinneret "spigots", called the cribellum, and spun with a "back-combing" movement of a special comb on the spider's rear legs.

This tiny spider has incorporated stabilimenta in her web. Stabilimenta are conspicuous lines or spirals of silk, included by many diurnal spiders at the center of their otherwise cryptic webs. It has been shown spider webs using stabilimenta catch, on average, 34% fewer insects than those without. However, webs with the easily-visible markings are damaged far less frequently by birds flying through the web. It is an evolutionary tradeoff the spider can influence every time it builds a new web. The inclusion of stabilimenta is influenced by many factors, including prey density and web location.  Read the scientific study at Behavioral Ecology magazine.

In any event, stabilimenta or no, a large Argiope planted firmly head-down in her web amongst tall weeds and grasses remains maddeningly invisible to man and beast. The black and yellow markings of the fat abdomen and striped legs function as camouflage much like the tigers' stripes do in the jungle - the geometric elements serve to break up the outline of the spiders' body and confuse the eye of the beholder into not recognizing the image. It is this principle upon which warships' hull camouflage was painted during the World Wars, with stark diagonal lines and shapes intended to keep an enemy from discerning the outline and identifying the size of the ship and the extent of its armaments.


I'm assuming the thorn-like appearance of the legs helps camouflage this spider.
 
              
 
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