Frequency, Patterns, and Construction of Web Decorations by the Spider Uloborus glomosus (Feather-legged Orbweaver)

Alexander M. Kerr*

*The Marine Laboratory, University of Guam, Mangilao, GU 96923 Guam, Territory of the USA.

Southeastern Naturalist, Volume 23, Issue 1 (2024): 1–12

First published early online: 16 February 2024

Abstract
Spiders in the genus Uloborus (Uloboridae) often include silken structures in their webs called stabilimenta or decorations whose function is still debated. Here, I report on the form, frequency, and construction of the decorations built by U. glomosus (Feather-legged Orbweaver) based on a field survey of 129 webs in southeastern North Carolina. About 87% of the webs were decorated. Among decorated webs, most (85%) consisted of 2 co-linear silk bands radiating from the hub. Other decoration types included a single radial band, central spirals, and a V-shaped device. A review of over 1300 images of Feather-legged Orbweaver curated at the online database iNaturalist revealed a further 5 rare or unique patterns. Decorations were aligned along the web's radius of steepest ascent. Decorating initiated from the web’s center with the laying outward along a radial strand of a thin “guide” silk over which the decoration was laid from the outside inwards. These observations are similar to those seen in the 2 other species of Uloborus studied in detail, suggesting a uniformity of the behavior across the genus.

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