Examine individual changes

'@@ -24,16 +24,94 @@ '''''Larinioides sclopetarius''''', commonly called '''bridge spider''' or '''gray cross spider''', is a relatively large [[orb-weaver spider]] with [[holarctic]] distribution. These spiders are located in Europe and have been observed as south as the Mediterranean Coast and as North as Finland. They are often found on bridges, especially near light and over water.<ref name="Roberts">Roberts, Michael J. (1996) ''Collins Field Guide: Spiders of Britain and Northern Europe'', Collins, {{ISBN|978-0-00-219981-0}}, pp. 321–2</ref> The species tends to live on steel objects and is seldom seen on vegetation.<ref>{{cite web |url=http://ednieuw.home.xs4all.nl/Spiders/Araneidae/Araneidae.htm |first=Ed |last=Nieuwenhuys |date=17 November 2013 |title=Orb web spiders or orb-weavers |accessdate=3 September 2014}}</ref> Females reach body length of 10–14mm, males 8–9mm.<ref name="Roberts" /> Their orb webs can have diameters of up to 70&nbsp;cm. -''L. sclopetarius'' is attracted to lights. Spiders found near light sources may be in better condition and have greater reproductive success than spiders living in unlit areas.<ref>{{Cite journal|last=Gomes|first=Dylan G.E.|date=2020-03-17|title=Orb-weaving spiders are fewer but larger and catch more prey in lit bridge panels from a natural artificial light experiment|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7083158/|journal=PeerJ|volume=8|doi=10.7717/peerj.8808|issn=2167-8359|pmc=7083158|pmid=32211243}}</ref> Most of these lighted areas are found in cities or other metropolitan areas. As a result, many urban areas have become saturated with these spiders. As many as 100 of these spiders can be found in a square meter in optimal feeding locations.<ref>{{Cite journal|last=Kralj-Fišer|first=Simona|last2=Hebets|first2=Eileen A.|last3=Kuntner|first3=Matjaž|date=2017-07-25|title=Different patterns of behavioral variation across and within species of spiders with differing degrees of urbanization|url=https://doi.org/10.1007/s00265-017-2353-x|journal=Behavioral Ecology and Sociobiology|language=en|volume=71|issue=8|pages=125|doi=10.1007/s00265-017-2353-x|issn=1432-0762}}</ref> +''L. sclopetarius'' is attracted to lights. Spiders found near light sources may be in better condition and have greater reproductive success than spiders living in unlit areas.<ref>{{Cite journal|last=Gomes|first=Dylan G.E.|date=2020-03-17|title=Orb-weaving spiders are fewer but larger and catch more prey in lit bridge panels from a natural artificial light experiment|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7083158/|journal=PeerJ|volume=8|doi=10.7717/peerj.8808|issn=2167-8359|pmc=7083158|pmid=32211243}}</ref> Most of these lighted areas are found in cities or other metropolitan areas. As a result, many urban areas have become saturated with these spiders. As many as 100 of these spiders can be found in a square meter in optimal feeding locations.<ref name=":1">{{Cite journal|last=Kralj-Fišer|first=Simona|last2=Hebets|first2=Eileen A.|last3=Kuntner|first3=Matjaž|date=2017-07-25|title=Different patterns of behavioral variation across and within species of spiders with differing degrees of urbanization|url=https://doi.org/10.1007/s00265-017-2353-x|journal=Behavioral Ecology and Sociobiology|language=en|volume=71|issue=8|pages=125|doi=10.1007/s00265-017-2353-x|issn=1432-0762}}</ref> They often hide during the day, and wait for prey in the center of their web at night. In high-density populations, spiders may remain sedentary to protect their territories. Mature females and juvenile spiders will often build webs. However, adult males generally inhabit adult female webs. Males can be found mostly during summer, females are active until November in Central Europe. == Description == -''L. sclopetarius'' creates circular webs that contrast the elliptical orb webs that many other orb-web spider form .<ref>{{Cite journal|last=Venner|first=S.|last2=Thevenard|first2=L.|last3=Pasquet|first3=A.|last4=Leborgne|first4=R.|date=2001-05-01|title=Estimation of the Web’s Capture Thread Length in Orb-Weaving Spiders: Determining the Most Efficient Formula|url=http://dx.doi.org/10.1603/0013-8746(2001)094[0490:eotwsc]2.0.co;2|journal=Annals of the Entomological Society of America|volume=94|issue=3|pages=490–496|doi=10.1603/0013-8746(2001)094[0490:eotwsc]2.0.co;2|issn=0013-8746}}</ref> Additionally, their orb-webs change shape the spider ages. As the spider matures, the adhesive web's lower-section will continue to increase whereas the web's upper section will become proportionally smaller.<ref>{{Cite journal|last=Herberstein|first=M.E.|last2=Heiling|first2=A.M.|date=1999-12|title=Asymmetry in spider orb webs: a result of physical constraints?|url=http://dx.doi.org/10.1006/anbe.1999.1255|journal=Animal Behaviour|volume=58|issue=6|pages=1241–1246|doi=10.1006/anbe.1999.1255|issn=0003-3472}}</ref> This discrepancy in web-size becomes more prominent as the spider gets larger. +''L. sclopetarius'' creates circular webs that contrast the elliptical orb webs that many other orb-web spider form .<ref>{{Cite journal|last=Venner|first=S.|last2=Thevenard|first2=L.|last3=Pasquet|first3=A.|last4=Leborgne|first4=R.|date=2001-05-01|title=Estimation of the Web’s Capture Thread Length in Orb-Weaving Spiders: Determining the Most Efficient Formula|url=http://dx.doi.org/10.1603/0013-8746(2001)094[0490:eotwsc]2.0.co;2|journal=Annals of the Entomological Society of America|volume=94|issue=3|pages=490–496|doi=10.1603/0013-8746(2001)094[0490:eotwsc]2.0.co;2|issn=0013-8746}}</ref> Additionally, their orb-webs change shape the spider ages. As the spider matures, the adhesive web's lower-section will continue to increase whereas the web's upper section will become proportionally smaller.<ref name=":2">{{Cite journal|last=Herberstein|first=M.E.|last2=Heiling|first2=A.M.|date=1999-12|title=Asymmetry in spider orb webs: a result of physical constraints?|url=http://dx.doi.org/10.1006/anbe.1999.1255|journal=Animal Behaviour|volume=58|issue=6|pages=1241–1246|doi=10.1006/anbe.1999.1255|issn=0003-3472}}</ref> This discrepancy in web-size becomes more prominent as the spider gets larger. They exhibit a slight sexual dimorphism where females are heavier than males. Females typically weigh around 60 mg, whereas males weigh around 38 mg.<ref name=":0">{{Cite journal|last=Kleinteich|first=Anja|date=2014|title=Evidence for Rensch’s rule in an orb-web spider with moderate sexual size dimorphism|url=|journal=Evolutionary Ecology Research|volume=12|pages=667-683|via=}}</ref> However, males may be slightly larger than females. Females can range from 4.5- 6.25 mm in length. Males vary from 4.25 mm to 7 mm in length.<ref name=":0" /> -''L. sclopetarius'' differs from its close relatives, ''L. patagiatus'' and ''L. cornutus'', with a few defining characteristics. Unlike the latter two species, ''L. sclopetarius'' has white hairs that provide a silhouette for their heads and dark markings on its abdomen.<ref>{{Cite journal|last=Fritzen|first=Niclas|date=2005|title=Larinioides sclopetarius and Agalenatea redii (Araneae: Araneidae) - Two spider species new to Finland|url=https://www.researchgate.net/publication/266327000_Larinioides_sclopetarius_and_Agalenatea_redii_Araneae_Araneidae_-_Two_spider_species_new_to_Finland|journal=Memoranda - Societatis Pro Fauna Et Flora Fennica|volume=81|pages=108-110|via=ResearchGate}}</ref> +''L. sclopetarius'' differs from its close relatives, ''L. patagiatus'' and ''L. cornutus'', with a few defining characteristics. Unlike the latter two species, ''L. sclopetarius'' has white hairs that provide a silhouette for their heads and dark markings on its abdomen.<ref name=":3">{{Cite journal|last=Fritzen|first=Niclas|date=2005|title=Larinioides sclopetarius and Agalenatea redii (Araneae: Araneidae) - Two spider species new to Finland|url=https://www.researchgate.net/publication/266327000_Larinioides_sclopetarius_and_Agalenatea_redii_Araneae_Araneidae_-_Two_spider_species_new_to_Finland|journal=Memoranda - Societatis Pro Fauna Et Flora Fennica|volume=81|pages=108-110|via=ResearchGate}}</ref> == Habitat and Distribution == +''L. sclopetarius'' is a spider found in Central Europe often found near water.<ref name=":4">{{Cite journal|last=Deventer|first=S. A.|last2=Herberstein|first2=M. E.|last3=Mayntz|first3=D.|last4=O'Hanlon|first4=J. C.|last5=Schneider|first5=J. M.|date=2017|title=Female fecundity and offspring survival are not increased through sexual cannibalism in the spider Larinioides sclopetarius|url=https://onlinelibrary.wiley.com/doi/abs/10.1111/jeb.13178|journal=Journal of Evolutionary Biology|language=en|volume=30|issue=12|pages=2146–2155|doi=10.1111/jeb.13178|issn=1420-9101}}</ref> They are most commonly found near artificial sources of light near the water such as bridges and boats. They often aggregate in high densities near the lights. The lights attract more insects increasing these spiders’ prey capture.<ref name=":5">{{Cite journal|last=Heiling|first=Astrid M.|date=1999-06-09|title=Why do nocturnal orb-web spiders (Araneidae) search for light?|url=http://dx.doi.org/10.1007/s002650050590|journal=Behavioral Ecology and Sociobiology|volume=46|issue=1|pages=43–49|doi=10.1007/s002650050590|issn=0340-5443}}</ref> Their light-seeking behaviors may have some genetic basis. + +In these feeding locations, adult females tend to occupy the best foraging areas. Juveniles and immature spiders are relegated to worse feeding areas when the competition is high.<ref name=":6">{{Cite journal|date=1999|title=THE IMPORTANCE OF BEING LARGER: INTRASPECIFIC COMPETITION FOR PRIME WEB SITES IN ORB-WEB SPIDERS (ARANEAE, ARANEIDAE)|url=http://dx.doi.org/10.1163/156853999501513|journal=Behaviour|volume=136|issue=5|pages=669–677|doi=10.1163/156853999501513|issn=0005-7959}}</ref> These behaviors may be observed due to juveniles being unable to compete for better territories. However, when these spiders mature, they often search for more illuminated areas to create their webs and lay their eggs. + +== Territoriality == +''L. sclopetarius'' is not a social spider.<ref name=":7">{{Cite book|last=Heiling|first=Astrid|url=http://www.european-arachnology.org/wdp/wp-content/uploads/2015/08/211-214_Heiling.pdf|title=Activity patterns in different developmental stages and sexes of Larinioides +sclopetarius (Clerck) (Araneae, Araneidae)|last2=Herberstein|first2=Marie|publisher=British Arachnological Society|year=1997|isbn=0-9500093-2-6|pages=211-214}}</ref> However, they often build webs next to each other.<ref name=":1" /> Females exhibit territorial defense of their webs from intruders, including other members of the same species. In high population densities, females exhibit more aggressive behavior to conspecifics due to shortages of territories.<ref name=":7" /> + +== Diet == +These spiders are primarily nocturnal foragers. Their prey capture fluctuates with the seasons. It is highest in the summer months, declining in the spring and fall. Chironomids consist of a significant portion of their diet.<ref name=":5" /> These small flies may comprise up to 94% of the spiders’ diets.<ref name=":8">{{Cite journal|last=Herberstein|first=Marie|last2=Heiling|first2=Astrid|date=1998|title=Does mesh height influence prey length in orb-web spiders (Araneae)?|url=https://www.eje.cz/pdfs/eje/1998/03/10.pdf|journal=European Journal of Entomology|volume=95|pages=367-371|via=}}</ref> Their prey's average size ranges from 1.2-6.8 mm. + +== Webs == +Spiders in high-prey areas have created webs with larger capture areas.<ref name=":2" /> These trends differ from other spiders such as ''A. keyserlingi'' where satiated spiders created smaller webs. + +''L. sclopetarius'' creates webs near sources of light. The part of the web adjacent to the light captures more prey than parts of the web farther away from the light .<ref name=":9">{{Cite journal|last=Herberstein|first=M. E.|last2=Heiling|first2=A. M.|date=2001-10|title=Positioning at the hub: does it matter on which side of the web orb-web spiders sit?|url=http://dx.doi.org/10.1017/s0952836901001224|journal=Journal of Zoology|volume=255|issue=2|pages=157–163|doi=10.1017/s0952836901001224|issn=0952-8369}}</ref> + +When resting in webs, these spiders tend to orient their posteriors in the direction of the wind. When the direction of the wind changes, the spider attempts to position itself back towards it. This behavior may have evolved to reduce the spider's risk of being blown off the web’s hub. Adhering to webs may be a challenge for ''L. sclopetarius'' in urban environments due to the lack of areas that can accommodate stable web sites under windy conditions.<ref name=":9" /> + +=== Web Type === +Adults create asymmetrical webs. The outer frame threads are generally similar in structure. The hubs, which are centers of the web, are also comparable to each other. The difference lies in the radii of the capture threads.<ref name=":2" /> The lower region radii of the capture threads are larger than the upper regions of the web. The web's unequal sizes may be due to the spider’s easier accessibility to the captured prey in the lower regions of the web.<ref name=":2" /> This capture web asymmetry increases with spider weight and gets more pronounced as the spiders age. Unlike adults, juveniles create symmetrical webs. + +=== Web Construction === +The mean mesh height, the distance between different capture threads, is approximately 2 mm.<ref name=":8" /> Yasuaki Murakami, a researcher from Kyushu University, found an interesting pattern where an increase in mesh height correlated with an increase in prey size.<ref>{{Cite journal|last=Murakami|first=Yasuaki|date=1983-03-01|title=Factors determining the prey size of the orb-web spider, Argiope amoena (L. Koch) (Argiopidae)|url=https://doi.org/10.1007/BF00379564|journal=Oecologia|language=en|volume=57|issue=1|pages=72–77|doi=10.1007/BF00379564|issn=1432-1939}}</ref> However, unlike many other spiders, including ''Micrathena gracilis'' and ''Argiope aurantia'', ''L. sclopetarius'' does not follow the trend of greater mesh height equating to capturing larger prey. One explanation may be the lack of prey diversity. Regardless of mesh height, ''L. sclopetarius'' primarily targets smaller dipterans. + +== Reproduction and Life cycle == +Males typically grow faster than females and mature into adults up to a month earlier.<ref name=":0" /> + +''L. sclopetarius'' has a life span of approximately 1.5 years in optimal conditions. They have an above average reproductive ability producing up to 15 egg sacs.<ref name=":10">{{Cite journal|last=Kleinteich|first=Anja|last2=Schneider|first2=Jutta M.|date=2011-02|title=Developmental strategies in an invasive spider: constraints and plasticity|url=http://doi.wiley.com/10.1111/j.1365-2311.2010.01249.x|journal=Ecological Entomology|language=en|volume=36|issue=1|pages=82–93|doi=10.1111/j.1365-2311.2010.01249.x}}</ref>   + +Unlike many spiders, development is independent from seasons. Adult spiders may become mature at any point during the year, however the greatest concentration of mature spiders occurs in late Summer.<ref name=":10" /> + +== Mating == +''L. sclopetarius'' exhibits many aggressive behaviors such as chasing and attacking conspecifics. If individuals are in the same web, they may engage in web-shaking contests. These aggressive behaviors may be genetically inherited. Assortative mating may be at play as aggressive males and females are more likely to mate with each other. Additionally, non-aggressive individuals are more likely to mate with each other.<ref name=":11">{{Cite journal|last=Kralj-Fiser|first=S.|last2=Sanguino Mostajo|first2=G. A.|last3=Preik|first3=O.|last4=Pekar|first4=S.|last5=Schneider|first5=J. M.|date=2013-04-18|title=Assortative mating by aggressiveness type in orb weaving spiders|url=https://doi.org/10.1093/beheco/art030|journal=Behavioral Ecology|volume=24|issue=4|pages=824–831|doi=10.1093/beheco/art030|issn=1045-2249}}</ref> There may be some male selection preferences as aggressive males may want to create the most aggressive males by mating with aggressive females for some practical benefits. Aggression may be selected as it may be needed to secure the best sites for web building around a light source. In some instances, groups of aggressive spiders may have lower mortality rates than mixed groups with non-aggressive and aggressive spiders.<ref name=":11" /> + +Aggressive males tend to create more fit males. Female reproductive success was partially dependent on female size rather than aggressiveness.<ref name=":11" /> + +=== Sexual Cannibalism === +Females may eat males when resources are scarce. Females that consume insects generally absorb more lipids, which provide a more efficient energy source. Sexual cannibalism does not seem to affect spider egg sac mass and clutch size because protein and lipid diets had elicited similar results.<ref name=":4" /> However, when food sources are scarce, spiderlings from females consuming high lipid diets may have better survival rates than spiderlings from females consuming high protein diets. Males may be seen as last-resort prey where there are no better options. + +Spiderlings from mothers who consumed male ''L. sclopetarius'' were observed spinning their webs sooner than mothers that solely ate insects.<ref name=":4" /> This observed behavior may either be due to the male providing necessary proteins for silk production or an environmental stressor that encouraged web building to compete in resource-scarce settings. + +== Social Behavior == +Female spiders live independently, defending their own webs. However, male spiders may have a kleptoparasitic relationship with the female choosing to live on a female’s web and steal their prey.<ref name=":7" /> + +''L. sclopetarius'' exhibits high levels of activities in unfamiliar environments, which may have contributed to their widespread colonization of urban areas.<ref name=":1" /> In experimental conditions, they tend to move and explore new settings more than their other urban counterparts ''Zygiella x-notata''. + +Males are generally more aggressive than females (<nowiki>https://link.springer.com/article/10.1007/s00265-017-2353-x</nowiki>).<ref name=":1" /> + +''L. sclopetarius'' typically positions itself on the lower areas of the web. This can be seen as a defensive behavior as it allows the spider to easily escape from the web from predators by using a safety line.<ref name=":9" /> + +== Physiology == + +=== Locomotion === +''L. sclopetarius'' for areas using a ballooning technique where the spider releases threads into the wind to travel. This method allows the spider to travel to preferable feeding areas.<ref name=":6" /> + +=== Glands and Toxins === +''L. sclopetarius'' secretes anti-adhesive compounds that prevent its legs from sticking to their capture threads.<ref>{{Cite journal|last=Kropf|first=Christian|last2=Bauer|first2=Dina|last3=Schläppi|first3=Thomas|last4=Jacob|first4=Alain|date=2012-02|title=An organic coating keeps orb-weaving spiders (Araneae, Araneoidea, Araneidae) from sticking to their own capture threads: An organic coating protects orb web spiders|url=http://doi.wiley.com/10.1111/j.1439-0469.2011.00648.x|journal=Journal of Zoological Systematics and Evolutionary Research|language=en|volume=50|issue=1|pages=14–18|doi=10.1111/j.1439-0469.2011.00648.x}}</ref> The mechanism for how the spiders develop and secrete this protection is currently unknown. + +=== Sexual Dimorphism === +This spider follows Rensch’s rule. Rensch’s rule states that male size is more variable than female size. There is only a small sexual dimorphism between males and females. Females grow slower and have more instars than males. As a result, they become heavier than males. Males grow faster and weigh approximately 40% of females. They also have longer legs and are larger than female spiders.<ref name=":0" /> These longer leg lengths may be due to mating advantages due to female choice or male competition. + +Diet may be related to male spider size. Poorer diets are associated with male spiders that possess shorter legs. Female spider size was unaffected by the quality of the diet.<ref name=":0" /> Female size may be undergoing stabilizing selection, which can explain the lack of variance in size despite diet changes. + +=== Protandry === +Male spiders exhibit protandry.<ref name=":0" /> The benefits for this behavior are unknown; the number of females able to breed throughout the year is relatively constant. Other factors that encourage protandry such as mate guarding and and time of mating were not seen in ''L. sclopetarius''. + +== Enemies == +''Phalacrotophora epeirae'' is one predator that consumes ''L. sclopetarius'' eggs.<ref>{{Cite journal|last=GUARISCO|first=HANK|date=2001-08|title=DESCRIPTION OF THE EGG SAC OF MIMETUS NOTIUS (ARANEAE, MIMETIDAE) AND A CASE OF EGG PREDATION BY PHALACROTOPHORA EPEIRAE (DIPTERA, PHORIDAE)|url=http://dx.doi.org/10.1636/0161-8202(2001)029[0267:doteso]2.0.co;2|journal=Journal of Arachnology|volume=29|issue=2|pages=267–269|doi=10.1636/0161-8202(2001)029[0267:doteso]2.0.co;2|issn=0161-8202}}</ref> + +''Trypoxylon attenuatum'' is a species of spider hunting wasp exhibited to hunt ''L. sclopetarius''.<ref>{{Cite journal|last=Asis|first=Josep Daniel|last2=Tormos|first2=Jose|last3=Gayubo|first3=Severiano Fernandez|date=1996-05-01|title=Behavior of Philanthus pulchellus (Hymenoptera: Sphecidae) with a Description of Its Mature Larva|url=https://academic.oup.com/aesa/article-lookup/doi/10.1093/aesa/89.3.452|journal=Annals of the Entomological Society of America|language=en|volume=89|issue=3|pages=452–458|doi=10.1093/aesa/89.3.452|issn=1938-2901}}</ref> These wasps are normally found in Southern Europe and prey on both foraging and sedentary spiders. ''T. attenuatum'' will paralyze spiders and bring them back to their nests. Once at the nest, ''L. sclopetarius'' may have an egg laid in it and serve as a food source for the wasp’s larvae. + +== Interactions with Humans == +''L. sclopetarius'' has been found in urban environments aggregating around sources of light. <ref name=":7" /> In Finland, they have been found in boats and boathouses.<ref name=":3" /> These spiders can migrate via boats which have caused them to be found in isolated islands such as the Aland Islands and spread over much of coastal Europe. They pose a hazard to local businesses as restaurant boats may experience a decline in productivity due to their web's frequent presence driving away customers. + +== Plasticity == +''L. sclopetarius'' shows high plasticity levels based on resource availability.<ref name=":10" /> These spiders exhibit variability in growth and weight gain between moulting periods. Their intermoult periods have a broader range of values than other spiders that inhabit urban environments such as ''Zygiella x‐notata''. + +Additionally, ''L. sclopetarius'' can alter its growth rate without increasing their risks of mortality.<ref name=":10" /> In resource-abundant areas, spiders have exhibited accelerated maturation. Their fast growth rates may allow them to colonize areas that can accommodate them. ==References== '