Orb-weaver spider | |
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Argiope catenulata | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Chelicerata |
Class: | Arachnida |
Order: | Araneae |
Infraorder: | Araneomorphae |
Superfamily: | Araneoidea |
Family: |
Araneidae Clerck, 1757 |
Genera | |
Diversity | |
169 genera, 3,097 species | |
Orb-weaver spiders or araneids are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields and forests. "Orb" was previously used in English to mean "circular", hence the English name of the group. Araneids have eight similar eyes, hairy or spiny legs, and no stridulating organs.
The family is cosmopolitan, including many well-known large or brightly colored garden spiders. With around 3,100 species in 169 genera worldwide, Araneidae is the third-largest family of spiders (behind Salticidae and Linyphiidae). Araneid webs are constructed in a stereotyped fashion. A framework of nonsticky silk is built up before the spider adds a final spiral of silk covered in sticky droplets.
Orb-webs are also produced by members of other spider families. The large golden orb-weavers (Nephilidae) and the long-jawed orb weavers (Tetragnathidae) were formerly included in the Araneidae; they are closely related, being part of the superfamily Araneoidea. It has recently been proposed that the family Arkyidae be split off from the Araneidae and the Nephilidae re-included, although as of October 2016[update] this has not been accepted by other sources. The cribellate or hackled orb-weavers (Uloboridae) belong to a different group of spiders. Their webs are strikingly similar, but use a different kind of sticky silk.
Generally, orb-weaving spiders are three-clawed builders of flat webs with sticky spiral capture silk. The building of a web is an engineering feat, begun when the spider floats a line on the wind to another surface. The spider secures the line and then drops another line from the center, making a "Y". The rest of the scaffolding follows with many radii of nonsticky silk being constructed before a final spiral of sticky capture silk.