Golden silk orbweaver (Nephila clavipes) adult female
Report and Photographs Courtesy of Sandra R., Houston, Texas, 12 July 2007
Jerry---Look what I found in my back yard in Houston, Texas!
Editor's Notes: The above photo is of the orb web, with the spider at its central hub. The photo below is an enlargement of the spider itself (note the tufts of black hairs on the legs, which are definitive for this species of orbweaver in the U.S.; the rectangular marking in the middle of the ventral abdomen is also definitive insofar as it differs from ventral abdominal markings found on members of spiders in the genus Neoscona).
The golden silk orbweaver (Nephila clavipes) is relatively large at maturity, and occurs in the southeastern U.S., from as far north as North Carolina, southward to Florida, and westward to Texas. Unlike the yellow garden spider (Argiope aurantia) which is found readily throughout much of its range, the golden silk orbweaver forms localized concentrations, especially near swampland or forested coastal regions, and is absent over much of its geographic range where conditions are not so favorable for its development. I have searched much of inland Texas for this species with very little success.
Nephila clavipes is a member of the Nephilidae family (until 2006, they were grouped under the Araneidae and Tetragnathidae, where they are listed in the authoritative work "Spiders of North America," Ubick et al, 2005 ed.) This family, known as large-jawed spiders, is presently divided into four genera of 75 species worldwide. They partially renew their webs, usually a section at a time, rather than performing a total dismantling and rebuilding as with many other spiders (e.g., Argiope spp.). They also abandon their old webs from time to time, to the temporary dismay of arachnology students observing their development. I say temporary, because they and their new web can usually be found close by the old one, after a bit of sleuthing. Such habits (both partial renewal and abandonment) are sometimes done in response to the presence of kleptoparasitic spiders in the genus Argyrodes who collect around orb webs to steal captured prey.
Nephilidae webs are unusually complex, though the full extent of that complexity is not immediately obvious. The unaware observer typically notices only the brighter, more obvious sticky spirals, not discerning the numerous non-sticky, less visible spirals between them. Indeed, the latter are so fine that they do not show on Sandra's photos (see the photo below). When spiders of other genera spin their webs, the non-sticky spirals (spun first upon a foundation of radial strands) are removed as the sticky spirals are spun afterward. The Nephila leave the non-sticky spirals in place, producing what appears, to those with good eyes and attention to detail, something analogous to the template for a musical score, awaiting a musician to add the notes of a great symphony. Conjure in your mind the sweet strains of a Brahms concerto, or perhaps a jaunty spate of Mozart, writ upon such a web... Then visualize the 40-hertz oscillations of an agitated Nephila clavipes, responding to the stimulation of its web by an intruder. Arachnology in motion. Beautiful... But I digress.
My Reply to Sandra:
When I replied to Sandra's message containing these photos, I could not hide my excitement. This species has been of great interest to me for some time, and I'd hoped to receive some good photos of it before long. Of course, I begged her to take more, especially of the dorsal abdomen and carapace, and--if possible--the eyes. She responded with excellent photos posted here.
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