# Stabilimentum

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Conspicuous, usually zig-zagged, silk structure in some orb-weaver spider webs

"web decoration" redirects here. For decorating World Wide Web pages, see [style sheet (web development)](/source/Style_sheet_(web_development)).

*[Argiope flavipalpis](/source/Argiope_(spider))* adult female

An *[Argiope](/source/Argiope_(spider))* juvenile female on the stabilimentum at the center of the web.

A **stabilimentum** (plural: **stabilimenta**), also known as a **web decoration**, is a conspicuous [silk](/source/Spider_silk) structure included in the webs of some species of [orb-web](/source/Spider_web#Types_of_spider_webs) [spider](/source/Spider). Its function is a subject of debate.

## Origin

Likely, the use of stabilimenta evolved independently at least nine different times. *[Araneus](/source/Araneus)* and *[Gasteracantha](/source/Gasteracantha)* make silk stabilimenta, while *[Cyclosa](/source/Cyclosa)* and the closely related *Allocyclosa bifurca* make stabilimenta of silk, detritus, and their egg sacs. All those evolved independently from those of *[Argiope](/source/Argiope_(spider))*, although some decorations of *Allocyclosa bifurca* closely resemble those of *Argiope*.[1]

## Form

Although web decorations are common in several spider species in the families [Araneidae](/source/Araneidae), [Tetragnathidae](/source/Tetragnathidae), and [Uloboridae](/source/Uloboridae), they are probably best known from spiders of the genus *[Argiope](/source/Argiope_(spider))*. This genus includes several species known as the *Saint Andrew's Cross spiders*, so named for their habit of resting in their webs with their legs outstretched in the shape of an X, the traditional shape of the [cross of Saint Andrew](/source/Saltire). *[Argiope argentata](/source/Argiope_argentata)*, more commonly known as silver argiopes, are also known for spinning stabilimenta into their web. These stabilimenta can appear as zig-zag lines, and most commonly come in bouts of four creating a center-less X.[2] Spiders in this genus also construct web decorations as vertical lines, and juveniles commonly construct disc-shaped decorations.[3] Other spiders construct round structures covering the entire hub of the web. Some *[Cyclosa](/source/Cyclosa)* spiders and *[Azilia vachoni](https://en.wikipedia.org/w/index.php?title=Azilia_vachoni&action=edit&redlink=1)* construct conspicuous stabilimenta with attached detritus such as egg sacs and insect carcasses (mostly their prey), and also hang debris such as dried leaves from their webs.[4] A specialized and highly complex form of detritus stabilimentum is constructed by at least two tropical *[Cyclosa](/source/Cyclosa)* species in Peru and the Philippines. These spiders meticulously arrange detritus and silk into a central mass with radiating appendages that visually resemble the silhouette of a much larger orb-weaving spider.[5]

		- The detail of the stabilimentum in the web of a female *[Argiope lobata](/source/Argiope_lobata)* showing its zig-zag structure and rostral location

		- *[Argiope aetherea](/source/Argiope_aetherea)* from Australia build X-shaped decorations

		- *Argiope* sp.

		- An *[Octonoba yaeyamensis](/source/Octonoba_yaeyamensis)* with a spiral stabilimentum

		- Oval spiral *Cyclosa* sp., [India](/source/India)

		- Detritus stabilimentum of *[Cyclosa](/source/Cyclosa) oculata*

## Function

There is much controversy surrounding the function of these structures, and different species likely use them for different purposes.

Originally the decorations were thought to stabilize the web (hence the term *stabilimentum*),[6] though this hypothesis has since been dismissed because it was found that the decoration is only loosely attached to the web so that the actual influence on the stability could only be minor.[7]

Notable is the fact that stabilimentum-building spiders are largely [diurnal](/source/Diurnality).[8] It has been suggested that stabilimenta could protect the spider by either camouflaging it (by breaking up its outline) or making it appear larger (by extending its outline).[9] The specialized stabilimenta of *[Cyclosa](/source/Cyclosa)* are hypothesized to function as a full-scale decoy.[5] By creating a silhouette resembling a larger, potentially threatening or non-prey spider species, the structure misdirects the attacks of visually hunting predators such as birds and damselflies away from the smaller, real spider.[5] The structure's appearance has also been discussed as a possible example of bird dropping mimicry, suggesting a multifaceted visual defense.[5] The fact that no orb weavers that build stabilimenta construct protective retreats and that no retreat-building species construct stabilimenta at least strongly suggests that these structures have a protective function, and that stabilimenta may be equivalents of protective retreats.[10]

Another hypothesis is that they make the web visible and therefore animals such as birds are less likely to damage the spider's web.[11][12][13] More recent work (2016) has leaned toward this latter hypothesis, further finding that food capture was reduced by their presence. The authors note that regardless of function, there is a high cost to building a stabilimentum, and therefore the benefit must be equally large.[8]

The other dominating hypothesis is that web decorations attract prey by reflecting [ultraviolet light](/source/Ultraviolet_light).[14] Light in the ultraviolet part of the spectrum is known to be attractive to many species of insects.[14]

Another hypothesis is that the purpose of the stabilimentum is to attract the male of the species to the web when the female is ready to reproduce. A limited study carried out in the Calahonda area of Spain in the summer of 1992 showed that there was a positive correlation between the presence of a male in the webs of *[Argiope lobata](/source/Argiope_lobata)* and the presence of a stabilimentum.[15][*[better source needed](https://en.wikipedia.org/wiki/Wikipedia:Verifiability#Questionable_sources)*] Many other hypotheses have also been proposed, such as thermoregulation,[16] stress[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*], or regulation of excess silk.[17] At least one species has been observed to vibrate the web, while positioned in the stabilimentum when approached by a body the size of a human.

While many *[Uloborus](/source/Uloborus)* species construct stabilimenta, *Uloborus gibbosus* does not; it usually rests at the edge of its orb and drops to the ground if disturbed. This is thought to support the web camouflage hypothesis. In contrast, the strongly UV-reflecting stabilimentum of the uloborid *[Octonoba](/source/Octonoba) sybotides* was found to be attractive to *[Drosophila](/source/Drosophila)* flies.[1]

Several evolutionary models were proposed for the inconsistency in function across species. Starks argued that although these hypotheses seemingly conflict, they might not be mutually exclusive, and suggested that we could take a hierarchical approach to model this problem: the predominant factor leading to stabilimentum production (i.e., the main function of the decoration) in each population might be different depending on the prey-and-predating context of that population.[7] For example, in an environment where the food is abundant but predation pressure is high, the food resources are less important than prey avoidance. Therefore, the stabilimentum might have little to no effect on attracting prey but functions well as a distraction from predators. Walter offered a similar but more specific solution.[18] He stated that the function of stabilimenta might not even be pattern or species-specific. Instead, he hypothesized that the visual signaling effect of stabilimenta might be derived from some non-signaling trait that is connected to other aspects of web-building behavior, such as silk disposition; this behavior was then selected preferentially to the specific ecological environment and therefore would be displayed through different patterns and functions among various habitats.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

In *[Cyclosa argenteoalba](/source/Cyclosa_argenteoalba),* web decorations were found to support Starks' hypothesis above in that they do not attract prey and instead deter predators. This was determined through experiments where the spiders produced longer silk decorations when there was an increased predation risk, but were not affected by the amount of available prey.[19]

## Materials

While the most conspicuous and well-studied decorations are constructed entirely of silk (for example in *[Argiope](/source/Argiope_(spider))*), some spiders combine silk with other items such as egg sacs and debris (for example in *[Cyclosa](/source/Cyclosa)*). For *[Cyclosa](/source/Cyclosa)* species, the structure is composed mainly of scavenged prey carcasses and plant detritus.[5] It seems likely that these decorations camouflage the spider, thus protecting it from predators.[20]

Something different occurs in some species of the golden orb spiders in the genus *[Nephila](/source/Nephila)*. These spiders commonly attach lines of uneaten prey items to their webs. Recent studies have shown that these items help the spider to attract more prey.[21]

## In popular culture

It is claimed that, after observing stabilimenta in a spider web, [E. B. White](/source/E._B._White) came up with the idea of a writing spider for his book *[Charlotte's Web](/source/Charlotte's_Web).*[22][23]

## See also

- [Spider web](/source/Spider_web)

## Footnotes

1. ^ [***a***](#cite_ref-FOOTNOTEEberhard2007_1-0) [***b***](#cite_ref-FOOTNOTEEberhard2007_1-1) [Eberhard 2007](#CITEREFEberhard2007).

1. **[^](#cite_ref-2)** ["SDNHM: Silver Argiope spider (Argiope argentata)"](https://web.archive.org/web/20120104221714/http://www.sdnhm.org/fieldguide/inverts/argi-arg.html). 4 January 2012. Archived from [the original](http://www.sdnhm.org/fieldguide/inverts/argi-arg.html) on 4 January 2012. Retrieved 14 December 2020.

1. **[^](#cite_ref-FOOTNOTEBruceHerberstein2005_3-0)** [Bruce & Herberstein 2005](#CITEREFBruceHerberstein2005).

1. **[^](#cite_ref-4)** Sewlal, Jo-Anne Nina (2016). "Possible Functions of the Detritus Stabilimentum and Hanging Detritus in Webs of *Azilia vachoni* (Araneae: Tetragnathidae)". *Arachnology*. **17** (1): 1–6. [doi](/source/Doi_(identifier)):[10.13156/arac.2006.17.1.1](https://doi.org/10.13156%2Farac.2006.17.1.1). [S2CID](/source/S2CID_(identifier)) [87967289](https://api.semanticscholar.org/CorpusID:87967289).

1. ^ [***a***](#cite_ref-:0_5-0) [***b***](#cite_ref-:0_5-1) [***c***](#cite_ref-:0_5-2) [***d***](#cite_ref-:0_5-3) [***e***](#cite_ref-:0_5-4) Olah, George; Torres, Phillip J.; Pomerantz, Aaron F.; Kirby, Richard; Baxter, Simon; Grados, Juan; Reeves, Lawrence E. (2025). ["Cyclosa Menge, 1866 (Araneidae) Orb-Weavers Build Stabilimenta That Resemble Larger Spiders"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12589895). *Ecology and Evolution*. **15** (11) e72371. [Bibcode](/source/Bibcode_(identifier)):[2025EcoEv..1572371O](https://ui.adsabs.harvard.edu/abs/2025EcoEv..1572371O). [doi](/source/Doi_(identifier)):[10.1002/ece3.72371](https://doi.org/10.1002%2Fece3.72371). [ISSN](/source/ISSN_(identifier)) [2045-7758](https://search.worldcat.org/issn/2045-7758). [PMC](/source/PMC_(identifier)) [12589895](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12589895). [PMID](/source/PMID_(identifier)) [41209359](https://pubmed.ncbi.nlm.nih.gov/41209359).

1. **[^](#cite_ref-FOOTNOTERobinsonRobinson1970_6-0)** [Robinson & Robinson 1970](#CITEREFRobinsonRobinson1970).

1. ^ [***a***](#cite_ref-FOOTNOTEStarks2002_7-0) [***b***](#cite_ref-FOOTNOTEStarks2002_7-1) [Starks 2002](#CITEREFStarks2002).

1. ^ [***a***](#cite_ref-beheco_8-0) [***b***](#cite_ref-beheco_8-1) Blackledge, Todd A.; Wenzel, John W. (1 July 1999). ["Do stabilimenta in orb webs attract prey or defend spiders?"](https://doi.org/10.1093%2Fbeheco%2F10.4.372). *Behavioral Ecology*. **10** (4). [Oxford University Press](/source/Oxford_University_Press): 372–376. [doi](/source/Doi_(identifier)):[10.1093/beheco/10.4.372](https://doi.org/10.1093%2Fbeheco%2F10.4.372). [ISSN](/source/ISSN_(identifier)) [1045-2249](https://search.worldcat.org/issn/1045-2249).

1. **[^](#cite_ref-FOOTNOTESchoenerSpiller1992_9-0)** [Schoener & Spiller 1992](#CITEREFSchoenerSpiller1992).

1. **[^](#cite_ref-FOOTNOTEWalter2024_10-0)** [Walter 2024](#CITEREFWalter2024).

1. **[^](#cite_ref-FOOTNOTEHerbersteinCraigCoddingtonElgar2000_11-0)** [Herberstein et al. 2000](#CITEREFHerbersteinCraigCoddingtonElgar2000).

1. **[^](#cite_ref-FOOTNOTEBruce2006_12-0)** [Bruce 2006](#CITEREFBruce2006).

1. **[^](#cite_ref-FOOTNOTEEisnerNowicki1983_13-0)** [Eisner & Nowicki 1983](#CITEREFEisnerNowicki1983).

1. ^ [***a***](#cite_ref-FOOTNOTECraigBernard1990_14-0) [***b***](#cite_ref-FOOTNOTECraigBernard1990_14-1) [Craig & Bernard 1990](#CITEREFCraigBernard1990).

1. **[^](#cite_ref-15)** Tickner 1992 (unpublished)

1. **[^](#cite_ref-FOOTNOTEHumphreys1992_16-0)** [Humphreys 1992](#CITEREFHumphreys1992).

1. **[^](#cite_ref-FOOTNOTETso2004_17-0)** [Tso 2004](#CITEREFTso2004).

1. **[^](#cite_ref-FOOTNOTEWalter2018_18-0)** [Walter 2018](#CITEREFWalter2018).

1. **[^](#cite_ref-19)** Nakata, Kensuke (November 2009). "To be or not to be conspicuous: the effects of prey availability and predator risk on spider's web decoration building". *Animal Behaviour*. **78** (5): 1255–1260. [Bibcode](/source/Bibcode_(identifier)):[2009AnBeh..78.1255N](https://ui.adsabs.harvard.edu/abs/2009AnBeh..78.1255N). [doi](/source/Doi_(identifier)):[10.1016/j.anbehav.2009.08.012](https://doi.org/10.1016%2Fj.anbehav.2009.08.012). [ISSN](/source/ISSN_(identifier)) [0003-3472](https://search.worldcat.org/issn/0003-3472). [S2CID](/source/S2CID_(identifier)) [53183028](https://api.semanticscholar.org/CorpusID:53183028).

1. **[^](#cite_ref-FOOTNOTEEberhard2003_20-0)** [Eberhard 2003](#CITEREFEberhard2003).

1. **[^](#cite_ref-FOOTNOTEBjorkman-ChiswellMuscatNguyenSymonds2004_21-0)** [Bjorkman-Chiswell et al. 2004](#CITEREFBjorkman-ChiswellMuscatNguyenSymonds2004).

1. **[^](#cite_ref-22)** [America's Wetland Foundation: Garden Spiders](https://americaswetlandresources.com/wildlife_ecology/plants_animals_ecology/animals/invertebrates/spiders/gardenspiders.html)

1. **[^](#cite_ref-23)** ["BugGuide.Net: Family Araneidae – Orb Weavers"](https://bugguide.net/node/view/1972). *[BugGuide](/source/BugGuide)*.

## References

- Bjorkman-Chiswell, Bojun T.; Muscat, Robert L.; Nguyen, Kim A.; Symonds, Matthew R. E.; Westhorpe, Gina E.; Elgar, Mark A.; Kulinski, Melissa M.; Norton, Briony A. (2004). "Web-building spiders attract prey by storing decaying matter". *Naturwissenschaften*. **91** (5): 245–248. [Bibcode](/source/Bibcode_(identifier)):[2004NW.....91..245B](https://ui.adsabs.harvard.edu/abs/2004NW.....91..245B). [doi](/source/Doi_(identifier)):[10.1007/s00114-004-0524-x](https://doi.org/10.1007%2Fs00114-004-0524-x). [PMID](/source/PMID_(identifier)) [15146274](https://pubmed.ncbi.nlm.nih.gov/15146274).

- Bruce, Matthew J.; Herberstein, Marie E. (2005). ["Web decoration polymorphism in *Argiope* Audouin, 1826 (Araneidae) spiders: Ontogenetic and interspecific variation"](http://www.bio.mq.edu.au/behaviouralecology/Marie%20page/Bruce%20&%20Herberstein%2005%20web%20dec%20polymorphism.pdf) (PDF). *Journal of Natural History*. **39** (44): 3833–3845. [Bibcode](/source/Bibcode_(identifier)):[2005JNatH..39.3833B](https://ui.adsabs.harvard.edu/abs/2005JNatH..39.3833B). [doi](/source/Doi_(identifier)):[10.1080/00222930500432182](https://doi.org/10.1080%2F00222930500432182).

- Bruce, M. J. (2006). "Silk decorations: Controversy and consensus". *Journal of Zoology*. **269** (1): 89–97. [Bibcode](/source/Bibcode_(identifier)):[2006JZoo..269...89B](https://ui.adsabs.harvard.edu/abs/2006JZoo..269...89B). [doi](/source/Doi_(identifier)):[10.1111/j.1469-7998.2006.00047.x](https://doi.org/10.1111%2Fj.1469-7998.2006.00047.x).

- Craig, Catherine L.; Bernard, Gary D. (1990). "Insect Attraction to Ultraviolet-Reflecting Spider Webs and Web Decorations". *Ecology*. **71** (2): 616–623. [Bibcode](/source/Bibcode_(identifier)):[1990Ecol...71..616C](https://ui.adsabs.harvard.edu/abs/1990Ecol...71..616C). [doi](/source/Doi_(identifier)):[10.2307/1940315](https://doi.org/10.2307%2F1940315). [JSTOR](/source/JSTOR_(identifier)) [1940315](https://www.jstor.org/stable/1940315).

- Eberhard, William (2003). "Substitution of silk stabilimenta for egg sacs by Allocyclosa bifurca (Araneae: Araneidae) suggests that silk stabilimenta function as camouflage devices". *Behaviour*. **140** (7): 847–868. [Bibcode](/source/Bibcode_(identifier)):[2003Behav.140..847E](https://ui.adsabs.harvard.edu/abs/2003Behav.140..847E). [doi](/source/Doi_(identifier)):[10.1163/156853903770238346](https://doi.org/10.1163%2F156853903770238346).

- Eberhard, William G. (2007). "Stabilimenta of *Philoponella vicina* (Araneae: Uloboridae) and *Gasteracantha cancriformis* (Araneae: Araneidae): Evidence Against a Prey Attractant Function". *Biotropica*. **39** (2): 216–220. [Bibcode](/source/Bibcode_(identifier)):[2007Biotr..39..216E](https://ui.adsabs.harvard.edu/abs/2007Biotr..39..216E). [doi](/source/Doi_(identifier)):[10.1111/j.1744-7429.2006.00254.x](https://doi.org/10.1111%2Fj.1744-7429.2006.00254.x).

- Eisner, Thomas; Nowicki, Stephen (1983). "Spider Web Protection Through Visual Advertisement: Role of the Stabilimentum". *Science*. **219** (4581): 185–187. [Bibcode](/source/Bibcode_(identifier)):[1983Sci...219..185E](https://ui.adsabs.harvard.edu/abs/1983Sci...219..185E). [doi](/source/Doi_(identifier)):[10.1126/science.219.4581.185](https://doi.org/10.1126%2Fscience.219.4581.185). [PMID](/source/PMID_(identifier)) [17841687](https://pubmed.ncbi.nlm.nih.gov/17841687).

- Herberstein, M. E.; Craig, C. L.; Coddington, J. A.; Elgar, M. A. (2000). "The functional significance of silk decorations of orb-web spiders: A critical review of the empirical evidence". *Biological Reviews*. **75** (4): 649–669. [doi](/source/Doi_(identifier)):[10.1111/j.1469-185x.2000.tb00056.x](https://doi.org/10.1111%2Fj.1469-185x.2000.tb00056.x). [PMID](/source/PMID_(identifier)) [11117202](https://pubmed.ncbi.nlm.nih.gov/11117202).

- Humphreys, W. F. (1992). ["Stabilimenta as parasols: shade construction by *Neogea* sp.(Araneae: Araneidae, Argiopinae) and its thermal behaviour"](https://britishspiders.org.uk/system/files/library/090204.pdf) (PDF). *Bulletin of the British Arachnological Society*. **9**: 42–47.

- Robinson, Michael H.; Robinson, Barbara (1970). "The Stabilimentum of the Orb Web SPIDER, *Argiope Argentata*: An Improbable Defence against Predators". *The Canadian Entomologist*. **102** (6): 641–655. [Bibcode](/source/Bibcode_(identifier)):[1970CaEnt.102..641R](https://ui.adsabs.harvard.edu/abs/1970CaEnt.102..641R). [doi](/source/Doi_(identifier)):[10.4039/Ent102641-6](https://doi.org/10.4039%2FEnt102641-6).

- Schoener, Thomasw.; Spiller, Davida. (1992). "Stabilimenta characteristics of the spider Argiope argentata on small islands: Support of the predator-defense hypothesis". *Behavioral Ecology and Sociobiology*. **31** (5): 309. [Bibcode](/source/Bibcode_(identifier)):[1992BEcoS..31..309S](https://ui.adsabs.harvard.edu/abs/1992BEcoS..31..309S). [doi](/source/Doi_(identifier)):[10.1007/BF00177771](https://doi.org/10.1007%2FBF00177771).

- Starks, Philip T. (2002). "The adaptive significance of stabilimenta in orb-webs: A hierarchical approach". *Annales Zoologici Fennici*. **39** (4): 307–315. [JSTOR](/source/JSTOR_(identifier)) [23735829](https://www.jstor.org/stable/23735829).

- Walter, André (2018). "Tracing the evolutionary origin of a visual signal: The coincidence of wrap attack and web decorating behaviours in orb web spiders (Araneidae)". *Evolutionary Ecology*. **32** (2–3): 159–170. [Bibcode](/source/Bibcode_(identifier)):[2018EvEco..32..159W](https://ui.adsabs.harvard.edu/abs/2018EvEco..32..159W). [doi](/source/Doi_(identifier)):[10.1007/s10682-018-9930-y](https://doi.org/10.1007%2Fs10682-018-9930-y).

- Walter, André (2024). ["The function of web decorations in orb web spiders"](https://doi.org/10.3389%2Ffrchs.2024.1384128). *Frontiers in Arachnid Science*. **3** 1384128. [doi](/source/Doi_(identifier)):[10.3389/frchs.2024.1384128](https://doi.org/10.3389%2Ffrchs.2024.1384128).

- Tso, I-Min (2004). "The Effect of Food and Silk Reserve Manipulation on Decoration-building of Argiope Aetheroides". *Behaviour*. **141** (5): 603–616. [Bibcode](/source/Bibcode_(identifier)):[2004Behav.141..603T](https://ui.adsabs.harvard.edu/abs/2004Behav.141..603T). [doi](/source/Doi_(identifier)):[10.1163/1568539041166690](https://doi.org/10.1163%2F1568539041166690).

## Further reading

- Blackledge, T. A. (1999). "Do stabilimenta in orb webs attract prey or defend spiders?". *Behavioral Ecology*. **10** (4): 372–376. [doi](/source/Doi_(identifier)):[10.1093/beheco/10.4.372](https://doi.org/10.1093%2Fbeheco%2F10.4.372).

## External links

Wikimedia Commons has media related to [Stabilimentum](https://commons.wikimedia.org/wiki/Category:Stabilimentum).

- [Large format reference photos: Argiope spider orb web with stabilimenta](https://cirrusimage.com/spider_argiope_aurantia.htm)

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Adapted from the Wikipedia article [Stabilimentum](https://en.wikipedia.org/wiki/Stabilimentum) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Stabilimentum?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.