Silver Argiope or Writing Spider

Description:

I found a large "colony" of these spiders on a patch of thick bushes. There were many females and juveniles, all having very large flimsy webs with round stabilimenta or "silk writing" in their centers. The circumference of the white circles matched the limits of the leg extensions of the spiders (small for juveniles, large for the females). The dozens of species of this genus make a variety of different stabilimenta, from long zig-zag lines to large X's to circles, as does this one. The 5th picture shows the stabilimentum from the underside, to appreciate the intricate design created by the Spider. The underside of the spider is visible in the 4th picture. There were many egg sacs scattered about, irregular in shape, yellowish in color and attached within the silk of the web, but not within the center hubs of writing (last picture).

Habitat:

These spiders were on a large patch of Sea Grape along the Atlantic side of the shoreline below the Fortress of San Felipe del Morro, San Juan, Puerto Rico.

Notes:

The web decorations of these spiders are fascinating and have been the subject of much study. They are known to reflect UV light and that has prompted the suspicion that they may attract prey. Other possibilities proposed are that they make the spider look larger, serve as camouflage or that they increase the visibility of the webs to large animals and birds to help prevent their accidental destruction. Personally, I prefer the latter explanation, since the creation of a web involves a great deal of work and effort and is not something to be easily sacrificed. See: https://en.wikipedia.org/wiki/Web_decora.... https://es.wikipedia.org/wiki/Argiope https://en.wikipedia.org/wiki/Argiope_(s...) https://www.forestryimages.org/browse/su...