Sit and wait predation in spiders

Spiders in the families Araneae, ** and ** build elaborate orb webs for catching prey. Like a fisherman choosing a spot to cast, orb-weaving spiders must locate themselves where prey (usually insects) are likely to fly. Spiders assess prey capture rates and relocate their webs if they build in a spot with a low yield. For example, in the spider Zygiella x-notata, prey capture stimulates the construction of smaller webs, presumably because once prey are discovered the same yield can be obtained with a smaller capture area (Venner et al. 2000).

This spider has built a more densely webbed, opaque, center, called a stabilimentum in its web. Several hypotheses have been proposed to explain the purpose of structures such as this in webs. In some cases they give birds a visual cue of the web's presence, protecting the web from damage when birds fly through it (Eisner and Nowicki 1983). However, such defense can be costly, both in construction materials and making prey capture less likely. Blackledge and Wenzel (1999) found that webs with stabilimenta captured 30% fewer prey than webs constructed by the same species of spider which lacked the structure.

In other spiders, the stabilimentum serves a defensive function, making the spider appear larger to potential predators (Schoener and Spiller 1992). Another hypothesis is that the stabilimentum actually attracts prey, but there is less experimental support for this idea. Schoener and Spiller (1992) noted that spiders with disk-shaped stabilimenta, like the one pictured here, run to the other side when approached by a predator. Depending on the spider species, stabilimenta may serve to protect the web, for defense of the spider itself, or for both purposes.

 

Blackledge T. A., Wenzel J. W. 1999. Do stabilimenta in orb webs attract prey or defend spiders? Behavioral Ecology 10: (4) 372-376

Eberhard W. G. 1990. Function and phylogeny of spider webs. Annu Rev Ecol Syst 21: 341-372

Eisner T., Nowicki S. 1983. Spider web protection through visual advertisement - role of the stabilimentum. Science 219: (4581) 185-187

Pasquet A., Ridwan A., Leborgne R. 1994 Presence of potential prey affects web-building in an orb-weaving spider Zygiella x notata. Animal Behaviour 47: (2) 477-480

Schoener T. W., Spiller D. A. 1992. Stabilimenta characteristics of the spider argiope-argentata on small islands - support of the predator-defense hypothesis. Behavioral Ecology And Sociobiology 31: (5) 309-318

Tanaka K. 1989. Energetic cost of web construction and its effect on web relocation in the web-building spider Agelena limbata Oecologia 81: (4) 459 464

Venner S., Pasquet A., Leborgne R. 2000. Web-building behaviour in the orb weaving spider Zygiella x-notata: influence of experience Animal Behaviour 59: 603-611

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copyright ©2001 Michael D. Breed, all rights reserved