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Wikipedia

Nephila

Nephila is a genus of araneomorph spiders noted for the impressive webs they weave. Nephila consists of numerous species found in warmer regions around the world, although some species formerly included in the genus have been moved to Trichonephila. They are commonly called golden silk orb-weavers, golden orb-weavers, giant wood spiders, or banana spiders.

Golden silk orb-weaver
Temporal range: Ypresian–present
Ventral side of N. pilipes, Agumbe Rainforest, India
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Nephilidae
Genus: Nephila
Leach, 1815[1]
Type species
Aranea pilipes
(Fabricius, 1793)[1]
Species

See text

Diversity[1]
11 species

Etymology edit

The genus name Nephila is derived from Ancient Greek, meaning "fond of spinning",[2] from the words νεῖν (nein) = to spin (related to nema νήμα "thread") + φίλος (philos) = "love".

Description edit

Nephila spiders vary from reddish to greenish yellow in color with distinctive whiteness on the cephalothorax and the beginning of the abdomen. Like many species of the superfamily Araneoidea, most of them have striped legs specialized for weaving (where their tips point inward, rather than outward as is the case with many wandering spiders). Their contrast of dark brown/black and green/yellow allows warning and repelling of potential predators to which their venom might be of little danger.

Golden orb-weavers reach sizes of 4.8–5.1 cm (1.5–2 in) in females, not including legspan, with males being usually two-thirds smaller (less than 2.5 cm, 1 in). In 2012, a large individual was photographed killing and consuming a 0.5-m-long brown tree snake in Freshwater, Queensland.[3] Species from Taiwan have been known to reach over 130 mm (5.1 in), legspan included, in mountainous country.[4] In 2014, a study discovered that golden orb-weavers living in urban areas, particularly areas of a high socioeconomic status, grew larger and carried more eggs than those in their native habitats. A number of possible explanations were suggested, such as increased food supplies due to artificial light or lack of predators and parasites.[5]

Species edit

In 2018, twelve Nephila species were reclassified as Trichonephila,[6] with another two (N. kuhlii and N. robusta) considered in 2020 to be junior synonyms of N. pilipes.[7] Species whose placement has been changed by some sources include:

  • Nephila laurinae was considered to be a synonym of Trichonephila antipodiana ("Batik Golden Web Spider"), found most commonly in the Philippines and Vietnam[8]
  • Trichonephila komaci, found most commonly in South Africa and Madagascar, transferred from Nephila komaci
  • Trichonephila clavipes (or "banana spider") found widely in warmer parts of the Americas, transferred from Nephila clavipes
  • Trichonephila inaurata (or "red-legged golden orb-weaver spider") found most commonly in southern and East Africa, transferred from Nephila inaurata
  • Trichonephila plumipes (or "tiger spider") found most commonly in Australia, transferred from Nephila plumipes

As of April 2024, the World Spider Catalog does not accept all of these changes, listing the following species in the genus Nephila:[1]

  • Nephila comorana Strand, 1916 – Comoros, Mayotte
  • Nephila constricta Karsch, 1879 – Tropical Africa
  • Nephila cornuta (Pallas, 1772) – Guyana
  • Nephila dirangensis Biswas & Biswas, 2006 – India
  • Nephila kuhli (Doleschall, 1859) – Myanmar to Indonesia
  • Nephila pakistaniensis Ghafoor & Beg, 2002 – Pakistan
  • Nephila pilipes (Fabricius, 1793) (type) – India to China, Vietnam, Philippines, Taiwan, Australia
  • Nephila tetragnathoides (Walckenaer, 1841) – Fiji, Tonga, Niue
  • Nephila vitiana (Walckenaer, 1847) – Indonesia, Fiji, Tonga

Additional fossil species are known from the Cenozoic. In 2012 Geratonephila burmanica was described from the Cenomanian aged Burmese amber, Wunderlich 2015 synonymised Geratonephilia with Nephilia tenuis, a species from the Dominican Amber, as he considered it unlikely that the amber was actually Burmese in origin.[9] Though largely ambiguous, the origins of Nephila are undoubtedly Gondowanan. With the prime candidates being Africa, Indomalaya, and Australasia.[10]

Distribution and habitat edit

Golden silk orb-weavers are widespread in warmer regions throughout the world, with species in Australia, Asia, Africa (including Madagascar), and the Americas. Spiderlings can be carried by the wind over long distances, and each year, a small number of female golden orb web spiders are found in New Zealand (where they are not endemic) after having been blown across the Tasman Sea; the spiders usually end up in the North Island.[11]

Whilst the geographic distribution of Nephila is large, many habitat similarities are seen between these locations. A warm and reasonably wet climate is generally preferred, as these are some of the environmental cues that induce spiderling hatching.[12] Locally, spiders look for relatively dense vegetation where webs can be set up in areas that insects will regularly fly through. Urban environments are also attractive due to the large prey concentrations and lower levels of predation.[13]

Behavior edit

Web spinning and structure edit

Nephila spiders produce large asymmetric orb webs up to 1.5 m (5 ft) in diameter.[citation needed] Nephila species remain in their webs permanently, so have a higher predation risk. The golden silk orb-weaver is named for the yellow color of the spider silk used to construct these webs.

Yellow threads of their web shine like gold in sunlight. Carotenoids are the main contributors to this yellow color, but xanthurenic acid, two quinones, and an unknown compound may also aid in the color.[14] Experimental evidence suggests that the silk's color may serve a dual purpose: sunlit webs ensnare bees that are attracted to the bright yellow strands, whereas in shady spots, the yellow blends in with background foliage to act as a camouflage. The spider is able to adjust pigment intensity relative to background light levels and color; the range of spectral reflectance is specifically adapted to insect vision.

The webs of most Nephila spiders are complex, with a fine-meshed orb suspended in a maze of non-sticky barrier webs. As with many weavers of sticky spirals, the orb is renewed regularly if not daily, apparently because the stickiness of the orb declines with age. When weather is good (and no rain has damaged the orb web), subadults and adults often rebuild only a portion of the web. The spider removes and consumes the portion to be replaced, builds new radial elements, then spins the new spirals. This partial orb renewal is distinct from other orb-weaving spiders that usually replace the entire orb web. The web of Nephila antipodiana contains ant-repellent chemicals to protect the web.[15]

Typically, the golden orb-weaver first weaves a nonsticky spiral with space for two to 20 more spirals in between (the density of sticky spiral strands decreases with increasing spider size).[citation needed] When she has completed the coarse weaving, she returns and fills in the gaps. Whereas most orb-weaving spiders remove the nonsticky spiral when spinning the sticky spiral, Nephila spiders leave it. This produces a "manuscript paper" effect when the orb is seen in the sun: groups of sticky spirals reflecting light with "gaps" where the nonsticky spiral does not reflect the light.

In relation to the ground, the webs of adults may be woven from eye-level upwards high into the tree canopy. The orb web is usually truncated by a top horizontal support strand, giving it an incomplete look.

Adjacent to one face of the main orb, a rather extensive and haphazard-looking network of guard-strands may be suspended a few centimeters distant across a free space. This network is often decorated with a lumpy string or two of plant detritus and insect carcasses clumped with silk. This "barrier web" may function as a kind of early-warning system for incoming prey or against spider-hunting predators, or as a shield against windblown leaves; it may also be remnants of the owner's previous web. At least one reference explains the suspended debris-chain as a cue for birds to avoid blundering into and destroying the web.

Prey capture and feeding edit

The golden silk orb-weaver targets many different organisms as prey, ranging from small flies and beetles to larger cicadas and locusts. As a result of their strong web structure, small birds and bats can also become trapped and fed upon. Whilst most of the captured prey is relatively small compared to Nephila, the majority of biomass consumed comes from larger, rarer prey. Prey larger than 66% of the captor's size accounts for just 16.5% of prey captured, but 85% of prey consumed, indicating the spider is selective in its feeding habits.[16]

Spiders are notified that potential prey has been caught in the web through vibrations along strands, and these can be followed to the prey location on the web and be used to estimate prey size.[13]

Nephila species also create caches of food for storage, which can be found above the hub of the web and contain up to 15 prey items. These items are arranged in a line vertically and are wrapped in silk to reduce dehydration. Caches are created and grow when prey is readily available and more biomass is available for consumption than is required by the spider. The purpose of caches is to have a backup food source when prey is scarce and occasionally to provide bait to attract more prey to the web.[17] Nephila species may also respond to food shortages by moving their webs, but this is a response to longer periods of prey scarcity than cache creation.[18] Web moving is seen as a result of environmental change, whereas caches occur from environmental fluctuation.

Mating and reproduction edit

 
N. pilipes female with many males

Nephila spiders display large sexual dimorphism in size, with females being greatly larger than males. Debate exists as to whether this is a result of male dwarfism or female gigantism.[citation needed] Smaller males may be selected for due to the presence of competition for mating. Smaller males are quicker and more nimble, allowing them to be able to catch the females more easily, as well as to escape when threatened. Larger males may have to wait for the female to come close due to their slower speed.[19] Larger females may have been selected for as a result of males using mating plugs upon copulation. Larger individuals reduce the success of these plugs, allowing for multiple mating and reducing the risk of genital mutilation.[20] Gigantism in females is also associated with fecundity, as larger individuals can produce more eggs and therefore increase reproductive success.[21]

When males are fully mature, they leave their webs to search for a suitable female, often using web characteristics to identify potential mates. Often, multiple males attempt to court the same female, thus competition for territory on the web occurs, but is rarely physical, as smaller males surrender area to larger ones. When males approach females, they are often feeding, allowing the males to get closer without an aggressive response and also meaning the female is not moving. On approach, the male makes himself known by tapping on a web strand to ensure the female is amenable before proceeding to mate. When met with aggression, males stop approaching and remain in the same location until the female relaxes or they retreat. Females engage in multiple mating, but no benefit to the offspring occurs as a result of this; however, the energy cost of repelling a male is higher than that of allowing him to copulate.[22] As a result of this, sperm competition occurs through males altering the duration and frequency of mating, with longer mating being proportional to a greater likelihood of success. Sexual cannibalism is uncommon in Nephila as a result of male mating behaviours. By copulating when females are immobile after molting or inactive due to feeding, the males increase their chances of survival. Males also approach from the side of the web opposite the female, increasing the odds of a successful approach.[23] Male Nephila pilipes is reported to have a mate binding behavior to avoid sexual cannibalism.[13] Sexual cannibalism does still occur, but generally is more common with larger males, and from older females.

Females produce an egg sac in the surrounding environs of the web to protect their eggs. The eggs are deposited on a silk platform, then are covered in loose silk to form a sac, which is firmly attached to surrounding vegetation so that it is hidden from the view of predators. It is reported that egg sacs are mostly under leaves and other coverings. However, only Nephila pilipes is different than other Nephila species. They lay eggs in small pits on the ground to avoid parasitism.[13] These sacs can contain from 300 to 3000 eggs, depending on mating success and particular species.[18] Once hatched, the spiderlings inhabit a communal web to begin their lives.

Thermoregulation edit

Nephila spiders change their body positioning relative to the sun to maintain internal temperatures at an optimal level. As ambient temperatures increase, the spiders position themselves so the abdomen shades the cephalothorax from the sun. Spiders may also hang from their hind legs as a result of the heat due to a loss of hydrostatic pressure. Conversely, as temperatures cool down, the spiders position themselves perpendicular to the sun to retain as much heat energy as possible. When ambient temperatures reach extreme highs (above 40 °C), they may leave their webs and seek shade in the surrounding environment.[24]

Predation and parasitism edit

Predation of Nephila species is relatively uncommon; when it does occur, the main group affected are the juvenile individuals. The major predators are birds, but wasps and damselflies also prey upon smaller juveniles.

Nephila species are frequently parasitized by Argyrodes, a genus of very small black-and-silver spiders that are kleptoparasitic. As many as a few dozen may infest a single Nephila web to feed from the host spider's captured prey. The frequent rebuilding or abandoning of webs by Nephila may be a tactic for controlling Argyrodes. Spiny orb-weaver spiders of the genus Gasteracantha also inhabit the webs of Nephila as kleptoparasites.

Egg sacs generally remain free from both predation and parasitism, often due to the close proximity of the mother and how well it is hidden.

Life cycle edit

Spiderlings edit

Nephila spiderlings leave the egg sac as a result of environmental cues, often warmer and wetter conditions in spring. They then live on a communal web, eating dead siblings and web debris for around a week before dispersing to make individual webs.[12]

Young spiders do not generally build yellow-colored silk, and the young themselves can be easily mistaken for young orchard spiders (Leucauge) in general color and shape (both genera sport silver stripes or patches on their abdomens, described in some references as a form of heat control). The best distinction between Leucauge and Nephila juveniles is web structure: Leucauge species tend to build horizontal orbs that form a perfect circle, whereas Nephila species build vertical, elliptical orbs that are incomplete (missing the portion of the orb over the hub, the center where the spider sits). The latter seem to prefer more open habitat such as second-growth scrub or forest edges. Fences or building overhangs often do just as nicely.

Molting and growth edit

Once they are juvenile, Nephila spiders inhabit their individual webs, then begin their growth by the molting process. The time between molts is called an instar and seven to 12 of these can occur depending on food availability. Ecdysis, the shedding of the exoskeleton, occurs through the formation of a soft exoskeleton inside the current one. Once the old exoskeleton is shed, the new, larger one begins to harden. Ecdysis occurs when the spider's mass becomes too great for the current exoskeleton to support.[25] Male spiders seek out females for copulation and live on their webs. When mating season arrives, both males and females stop molting and remain the same size for the remainder of their lives.

Venom edit

The venom of the golden silk orb-weaver is effective in action on prey, but has not been reported to be of any notable consequence for humans if accidentally bitten. In the literature, Nephila is one of several genera where the venom "must be considered as more or less ineffectual in human beings".[26] That said, the potentially large size of several members of the genus means that they possess relatively strong chelicerae, so any bite can cause some mechanical damage, but only of short-term localised effect for humans. However, further studies of the venom components are needed to better understand pathways associated with any toxicity.

Interaction with humans edit

Nephila do not seem to form either beneficial or harmful relationships with humans. Females often construct their webs using human structures as a base for support strands due to their stability. Individuals are often found in urban and suburban environments due to the protection from predation and greater prey availability.[27] As they weave their webs in bushes and near flowers, they might present a nuisance for gardeners or flower pickers. Some nests near fruits may repel or destroy known pests, such as Tephritid fruit flies, without the need to use insecticides. Spiders may bite humans if provoked but more often flee if confronted.

Golden silk edit

 
Cape made from Madagascar golden orb-weaver spider silk, Victoria and Albert Museum, London[28]

There have been several efforts in the past to produce garments from Nephila silk although none commercially viable.[29] These include two bed hangings that were shown at the 1900 Paris Exhibition.[30] In 2004 a textile designer, Simon Peers, and an entrepreneur, Nicholas Godley managed in three years' work and using 1.2 million Golden silk orb-weavers (collected in the wild and released some 30 minutes later after they produced the silk) to produce a shawl that was exhibited at the American Museum of Natural History in 2009.[31][32] By 2012 they managed to produce a second, bigger garment, a cape, that, together with the shawl, were exhibited at the Victoria and Albert Museum in London.[33] Two shawls and a traditional Madagascan lamba made of this spider silk were included in an exhibition of curios from the natural world in 2021.[34]

Another possible use of Nephila silk lies in tissue engineering. A study from the Medizinische Hochschule Hannover reports that processed Nephila silk is an excellent scaffold material thanks to its biocompatibility, mechanical strengths, and its property to promote cell adhesion and proliferation.[clarification needed][35] In particular, the silk acts as a suitable guiding material for peripheral nerve regrowth.[36]

Fishermen on the coasts of the Indo-Pacific ocean remove Nephila webs and form them into a ball, which is thrown into the water. There it unfolds and is used to catch bait fish.[29]

References edit

  1. ^ a b c d "Gen. Nephila Leach, 1815". World Spider Catalog. Natural History Museum Bern. Retrieved 2017-05-13.
  2. ^ Cameron, H. D. (2005). "Chapter 73: An etymological dictionary of North American spider genus names". In Ubick, Darrell; Paquin, Pierre; Cushing, Paula E.; et al. (eds.). Spiders of North America: An identification manual. American Arachnological Society. ISBN 9780977143900. OCLC 502287303.
  3. ^ Serenc, Michael (19 April 2012). . The Cairns Post. Archived from the original on 21 April 2012. Retrieved 17 August 2012.
  4. ^ Gallagher, Terry. "Giant 'gentle spiders' collected in Taiwan for study at U-M-Dearborn". The University Record Online. University of Michigan. Retrieved 17 August 2012.
  5. ^ Thompson, Helen (August 20, 2014). "Friendly Neighborhood Spiders Get Bigger in Cities". Smithsonian. Retrieved August 21, 2014.
  6. ^ Matjaz, Kuntner; Hamilton, Chris A.; Cheng, Ren-Chung (2018-12-04). "Golden Orbweavers Ignore Biological Rules: Phylogenomic and Comparative Analyses Unravel a Complex Evolution of Sexual Size Dimorphism". Systematic Biology. 68 (4): 555–572. doi:10.1093/sysbio/syy082. PMC 6568015. PMID 30517732. Retrieved 23 October 2021.
  7. ^ Sankaran, Pradeep (2020-06-04). "On a new synonymy in the spider genus Nephila Leach, 1815 (Araneidae, Nephilinae) from India with supplementary notes on colour polymorphism in the genus". Zootaxa. 4786 (4: 4 Jun. 2020): 594. doi:10.11646/zootaxa.4786.4.11. PMID 33056468. S2CID 219923219. Retrieved 23 October 2021.
  8. ^ Yuan, Tao; Zhang, Zhisheng (2020-12-04). "Molecular evidence that Trichonephila antipodiana and Nephila laurinae may be the same species". Acta Arachnida. 29 (2): 120. doi:10.3969/j.issn.1005-9628.2020.02.010. Retrieved 23 October 2021.
  9. ^ Selden, Paul A.; Ren, Dong (November 2017). "A review of Burmese amber arachnids". Journal of Arachnology. 45 (3): 324–343. doi:10.1636/JoA-S-17-029. ISSN 0161-8202. S2CID 90983791.
  10. ^ Turk, Eva; Čandek, Klemen; Kralj-Fišer, Simona; Kuntner, Matjaž (June 2020). "Biogeographical history of golden orbweavers: Chronology of a global conquest". Journal of Biogeography. 47 (6): 1333–1344. Bibcode:2020JBiog..47.1333T. doi:10.1111/jbi.13838. ISSN 0305-0270. S2CID 218778879.
  11. ^ Sivignon, Cherie (19 March 2016). "Giant spider feast for moreport?". The Press. p. A18. Retrieved 19 March 2016.
  12. ^ a b Higgins, L. (2017). Nephila Life Cycle. [online] Uvm.edu. Available at: http://www.uvm.edu/~lehiggin/LifeCycle.html [Accessed 30 May 2017].
  13. ^ a b c d Harvey, Mark S.; Austin, Andrew D.; Adams, Mark (2007). "The systematics and biology of the spider genus Nephila (Araneae: Nephilidae) in the Australasian region". Invertebrate Systematics. 21 (5): 407. doi:10.1071/is05016. ISSN 1445-5226.
  14. ^ Hsiung, Bor-Kai; Justyn, Nicholas M.; Blackledge, Todd A.; Shawkey, Matthew D. (2017-06-01). "Spiders have rich pigmentary and structural colour palettes". Journal of Experimental Biology. 220 (11): 1975–1983. doi:10.1242/jeb.156083. PMID 28566355.
  15. ^ Phillips, Campbell (23 November 2011). "Golden orb web spider spins ant-repellent silk". Australian Geographic. Retrieved 16 August 2012.
  16. ^ Blackledge, T (2011). "Prey capture in orb weaving spiders: are we using the best metric?". Journal of Arachnology. 39 (2): 205–210. doi:10.1636/chi10-52.1. S2CID 54578394.
  17. ^ Champion; de Crespigny, F.; Herberstein, M.; Elgar, M. (2001). "Food caching in orb-web spiders (Araneae: Araneoidea)". Naturwissenschaften. 88 (1): 42–45. Bibcode:2001NW.....88...42C. doi:10.1007/s001140000194. PMID 11261355. S2CID 21994595.
  18. ^ a b Robinson, M. and Robinson, B. (1973). Ecology and behavior of the giant wood spider Nephila maculata (Fabricius) in New Guinea. Smithsonian Contributions to Zoology, (149), pp.1-76.
  19. ^ Coddington, Jonathan; Hormiga, G; Scharff, N (1997). "Giant female or dwarf male spiders?". Nature. 385 (6618): 687–688. Bibcode:1997Natur.385..687C. doi:10.1038/385687a0. S2CID 4308746.
  20. ^ Kuntner, Matjaž; Kralj-Fišer, S.; Schneider, Jutta; Li, Daiqin (2009). "Mate Plugging Via Genital Mutilation In Nephilid Spiders: An Evolutionary Hypothesis". Journal of Zoology. 277 (4): 257–266. doi:10.1111/j.1469-7998.2008.00533.x.
  21. ^ Kuntner, Matjaž; Zhang, Shichang; Gregorič, Matjaž; Li, Daiqin (2012). "Nephila Female Gigantism Attained through Post-maturity Molting". Journal of Arachnology. 40 (3): 345–347. doi:10.1636/b12-03.1. S2CID 30430184.
  22. ^ Smith, R. (1984). Sperm Competition and the Evolution of Animal Mating systems. 1st ed. Elsevier, pp.223-250.
  23. ^ Fromhage, L.; Schneider, J. (2004). "Safer sex with feeding females: sexual conflict in a cannibalistic spider". Behavioral Ecology. 16 (2): 377–382. doi:10.1093/beheco/ari011.
  24. ^ Humphreys, W. F. (1993). Criteria for identifying thermal behaviour in spiders: a low technology approach. Memoirs of the Queensland Museum 33, 543–550.
  25. ^ Higgins, L. (2017). "Summer: Growth by Molting". uvm.edu. The University of Vermont.
  26. ^ Bücherl, W.; Buckley, E.E. (1971). Venomous Animals and Their Venoms: Volume III Venomous Invertebrates. Academic Press. p. 562.
  27. ^ Australian Geographic (August 2014). "Spiders in the city are bigger".
  28. ^ Kennedy, Maev (24 January 2012). "Spider silk cape goes on show at V&A". The Guardian. London. Retrieved 17 August 2012.
  29. ^ a b Heimer, S. (1988). Wunderbare Welt der Spinnen. Urania. p.14
  30. ^ "Spider silk at the V&A: A tangled (and exquisite) web they wove | The Economist". economist.com. 25 January 2012. Retrieved 18 August 2012. 1900 Paris Exhibition
  31. ^ Leggett, Hadley (23 September 2009). "1 Million Spiders Make Golden Silk for Rare Cloth". Wired Science. Retrieved 17 August 2012.
  32. ^ American Museum of Natural History (24 September 2009). Rare Spider Silk on Exhibit at AMNH. YouTube.com. Archived from the original on 2021-12-21. Retrieved 17 August 2012.
  33. ^ "Spider silk at the V&A: A tangled (and exquisite) web they wove | The Economist". economist.com. 25 January 2012. Retrieved 18 August 2012. Simon Peers, a textile designer, and Nicholas Godley, an entrepreneur,
  34. ^ "Eight years and 2m arachnids later, spider silk fabrics go on show in London". the Guardian. 2021-09-06. Retrieved 2021-09-21.
  35. ^ "Biocompatible matrix for tissue engineering and wound dressing". 2010-07-19. Retrieved 2011-02-23.
  36. ^ [Peripheral nervous tissue engineering with spider silk] (in German). Hannover: Klinik für Plastische, Hand- und Wiederherstellungschirurgie der Medizinischen Hochschule Hannover. Archived from the original on 3 December 2012. Retrieved 17 August 2012.

External links edit

  •   Data related to Nephila at Wikispecies
  •   Media related to Nephila at Wikimedia Commons
  • Pictures of golden silk orb-weavers
  • A Golden Spider-Silk Textile at the Art Institute of Chicago on YouTube

nephila, aramaic, culture, orion, constellation, race, mentioned, book, genesis, nephilim, genus, araneomorph, spiders, noted, impressive, webs, they, weave, consists, numerous, species, found, warmer, regions, around, world, although, some, species, formerly,. For the use in Aramaic culture see Orion constellation For the race mentioned in the Book of Genesis see Nephilim Nephila is a genus of araneomorph spiders noted for the impressive webs they weave Nephila consists of numerous species found in warmer regions around the world although some species formerly included in the genus have been moved to Trichonephila They are commonly called golden silk orb weavers golden orb weavers giant wood spiders or banana spiders Golden silk orb weaverTemporal range Ypresian present PreꞒ Ꞓ O S D C P T J K Pg N Ventral side of N pilipes Agumbe Rainforest India Scientific classification Domain Eukaryota Kingdom Animalia Phylum Arthropoda Subphylum Chelicerata Class Arachnida Order Araneae Infraorder Araneomorphae Family Nephilidae Genus NephilaLeach 1815 1 Type species Aranea pilipes Fabricius 1793 1 Species See text Diversity 1 11 species Contents 1 Etymology 2 Description 3 Species 4 Distribution and habitat 5 Behavior 5 1 Web spinning and structure 5 2 Prey capture and feeding 5 3 Mating and reproduction 5 4 Thermoregulation 5 5 Predation and parasitism 6 Life cycle 6 1 Spiderlings 6 2 Molting and growth 7 Venom 8 Interaction with humans 8 1 Golden silk 9 References 10 External linksEtymology editThe genus name Nephila is derived from Ancient Greek meaning fond of spinning 2 from the words neῖn nein to spin related to nema nhma thread filos philos love Description editNephila spiders vary from reddish to greenish yellow in color with distinctive whiteness on the cephalothorax and the beginning of the abdomen Like many species of the superfamily Araneoidea most of them have striped legs specialized for weaving where their tips point inward rather than outward as is the case with many wandering spiders Their contrast of dark brown black and green yellow allows warning and repelling of potential predators to which their venom might be of little danger Golden orb weavers reach sizes of 4 8 5 1 cm 1 5 2 in in females not including legspan with males being usually two thirds smaller less than 2 5 cm 1 in In 2012 a large individual was photographed killing and consuming a 0 5 m long brown tree snake in Freshwater Queensland 3 Species from Taiwan have been known to reach over 130 mm 5 1 in legspan included in mountainous country 4 In 2014 a study discovered that golden orb weavers living in urban areas particularly areas of a high socioeconomic status grew larger and carried more eggs than those in their native habitats A number of possible explanations were suggested such as increased food supplies due to artificial light or lack of predators and parasites 5 Species editIn 2018 twelve Nephila species were reclassified as Trichonephila 6 with another two N kuhlii and N robusta considered in 2020 to be junior synonyms of N pilipes 7 Species whose placement has been changed by some sources include Nephila laurinae was considered to be a synonym of Trichonephila antipodiana Batik Golden Web Spider found most commonly in the Philippines and Vietnam 8 Trichonephila komaci found most commonly in South Africa and Madagascar transferred from Nephila komaci Trichonephila clavipes or banana spider found widely in warmer parts of the Americas transferred from Nephila clavipes Trichonephila inaurata or red legged golden orb weaver spider found most commonly in southern and East Africa transferred from Nephila inaurata Trichonephila plumipes or tiger spider found most commonly in Australia transferred from Nephila plumipes As of April 2024 update the World Spider Catalog does not accept all of these changes listing the following species in the genus Nephila 1 Nephila comorana Strand 1916 Comoros Mayotte Nephila constricta Karsch 1879 Tropical Africa Nephila cornuta Pallas 1772 Guyana Nephila dirangensis Biswas amp Biswas 2006 India Nephila kuhli Doleschall 1859 Myanmar to Indonesia Nephila pakistaniensis Ghafoor amp Beg 2002 Pakistan Nephila pilipes Fabricius 1793 type India to China Vietnam Philippines Taiwan Australia Nephila tetragnathoides Walckenaer 1841 Fiji Tonga Niue Nephila vitiana Walckenaer 1847 Indonesia Fiji Tonga Additional fossil species are known from the Cenozoic In 2012 Geratonephila burmanica was described from the Cenomanian aged Burmese amber Wunderlich 2015 synonymised Geratonephilia with Nephilia tenuis a species from the Dominican Amber as he considered it unlikely that the amber was actually Burmese in origin 9 Though largely ambiguous the origins of Nephila are undoubtedly Gondowanan With the prime candidates being Africa Indomalaya and Australasia 10 nbsp N kuhlii dorsal side nbsp N kuhlii ventral sideDistribution and habitat editGolden silk orb weavers are widespread in warmer regions throughout the world with species in Australia Asia Africa including Madagascar and the Americas Spiderlings can be carried by the wind over long distances and each year a small number of female golden orb web spiders are found in New Zealand where they are not endemic after having been blown across the Tasman Sea the spiders usually end up in the North Island 11 Whilst the geographic distribution of Nephila is large many habitat similarities are seen between these locations A warm and reasonably wet climate is generally preferred as these are some of the environmental cues that induce spiderling hatching 12 Locally spiders look for relatively dense vegetation where webs can be set up in areas that insects will regularly fly through Urban environments are also attractive due to the large prey concentrations and lower levels of predation 13 Behavior editWeb spinning and structure edit Nephila spiders produce large asymmetric orb webs up to 1 5 m 5 ft in diameter citation needed Nephila species remain in their webs permanently so have a higher predation risk The golden silk orb weaver is named for the yellow color of the spider silk used to construct these webs Yellow threads of their web shine like gold in sunlight Carotenoids are the main contributors to this yellow color but xanthurenic acid two quinones and an unknown compound may also aid in the color 14 Experimental evidence suggests that the silk s color may serve a dual purpose sunlit webs ensnare bees that are attracted to the bright yellow strands whereas in shady spots the yellow blends in with background foliage to act as a camouflage The spider is able to adjust pigment intensity relative to background light levels and color the range of spectral reflectance is specifically adapted to insect vision The webs of most Nephila spiders are complex with a fine meshed orb suspended in a maze of non sticky barrier webs As with many weavers of sticky spirals the orb is renewed regularly if not daily apparently because the stickiness of the orb declines with age When weather is good and no rain has damaged the orb web subadults and adults often rebuild only a portion of the web The spider removes and consumes the portion to be replaced builds new radial elements then spins the new spirals This partial orb renewal is distinct from other orb weaving spiders that usually replace the entire orb web The web of Nephila antipodiana contains ant repellent chemicals to protect the web 15 Typically the golden orb weaver first weaves a nonsticky spiral with space for two to 20 more spirals in between the density of sticky spiral strands decreases with increasing spider size citation needed When she has completed the coarse weaving she returns and fills in the gaps Whereas most orb weaving spiders remove the nonsticky spiral when spinning the sticky spiral Nephila spiders leave it This produces a manuscript paper effect when the orb is seen in the sun groups of sticky spirals reflecting light with gaps where the nonsticky spiral does not reflect the light In relation to the ground the webs of adults may be woven from eye level upwards high into the tree canopy The orb web is usually truncated by a top horizontal support strand giving it an incomplete look Adjacent to one face of the main orb a rather extensive and haphazard looking network of guard strands may be suspended a few centimeters distant across a free space This network is often decorated with a lumpy string or two of plant detritus and insect carcasses clumped with silk This barrier web may function as a kind of early warning system for incoming prey or against spider hunting predators or as a shield against windblown leaves it may also be remnants of the owner s previous web At least one reference explains the suspended debris chain as a cue for birds to avoid blundering into and destroying the web Prey capture and feeding edit The golden silk orb weaver targets many different organisms as prey ranging from small flies and beetles to larger cicadas and locusts As a result of their strong web structure small birds and bats can also become trapped and fed upon Whilst most of the captured prey is relatively small compared to Nephila the majority of biomass consumed comes from larger rarer prey Prey larger than 66 of the captor s size accounts for just 16 5 of prey captured but 85 of prey consumed indicating the spider is selective in its feeding habits 16 Spiders are notified that potential prey has been caught in the web through vibrations along strands and these can be followed to the prey location on the web and be used to estimate prey size 13 Nephila species also create caches of food for storage which can be found above the hub of the web and contain up to 15 prey items These items are arranged in a line vertically and are wrapped in silk to reduce dehydration Caches are created and grow when prey is readily available and more biomass is available for consumption than is required by the spider The purpose of caches is to have a backup food source when prey is scarce and occasionally to provide bait to attract more prey to the web 17 Nephila species may also respond to food shortages by moving their webs but this is a response to longer periods of prey scarcity than cache creation 18 Web moving is seen as a result of environmental change whereas caches occur from environmental fluctuation Mating and reproduction edit nbsp N pilipes female with many males Nephila spiders display large sexual dimorphism in size with females being greatly larger than males Debate exists as to whether this is a result of male dwarfism or female gigantism citation needed Smaller males may be selected for due to the presence of competition for mating Smaller males are quicker and more nimble allowing them to be able to catch the females more easily as well as to escape when threatened Larger males may have to wait for the female to come close due to their slower speed 19 Larger females may have been selected for as a result of males using mating plugs upon copulation Larger individuals reduce the success of these plugs allowing for multiple mating and reducing the risk of genital mutilation 20 Gigantism in females is also associated with fecundity as larger individuals can produce more eggs and therefore increase reproductive success 21 When males are fully mature they leave their webs to search for a suitable female often using web characteristics to identify potential mates Often multiple males attempt to court the same female thus competition for territory on the web occurs but is rarely physical as smaller males surrender area to larger ones When males approach females they are often feeding allowing the males to get closer without an aggressive response and also meaning the female is not moving On approach the male makes himself known by tapping on a web strand to ensure the female is amenable before proceeding to mate When met with aggression males stop approaching and remain in the same location until the female relaxes or they retreat Females engage in multiple mating but no benefit to the offspring occurs as a result of this however the energy cost of repelling a male is higher than that of allowing him to copulate 22 As a result of this sperm competition occurs through males altering the duration and frequency of mating with longer mating being proportional to a greater likelihood of success Sexual cannibalism is uncommon in Nephila as a result of male mating behaviours By copulating when females are immobile after molting or inactive due to feeding the males increase their chances of survival Males also approach from the side of the web opposite the female increasing the odds of a successful approach 23 Male Nephila pilipes is reported to have a mate binding behavior to avoid sexual cannibalism 13 Sexual cannibalism does still occur but generally is more common with larger males and from older females Females produce an egg sac in the surrounding environs of the web to protect their eggs The eggs are deposited on a silk platform then are covered in loose silk to form a sac which is firmly attached to surrounding vegetation so that it is hidden from the view of predators It is reported that egg sacs are mostly under leaves and other coverings However only Nephila pilipes is different than other Nephila species They lay eggs in small pits on the ground to avoid parasitism 13 These sacs can contain from 300 to 3000 eggs depending on mating success and particular species 18 Once hatched the spiderlings inhabit a communal web to begin their lives Thermoregulation edit Nephila spiders change their body positioning relative to the sun to maintain internal temperatures at an optimal level As ambient temperatures increase the spiders position themselves so the abdomen shades the cephalothorax from the sun Spiders may also hang from their hind legs as a result of the heat due to a loss of hydrostatic pressure Conversely as temperatures cool down the spiders position themselves perpendicular to the sun to retain as much heat energy as possible When ambient temperatures reach extreme highs above 40 C they may leave their webs and seek shade in the surrounding environment 24 Predation and parasitism edit Predation of Nephila species is relatively uncommon when it does occur the main group affected are the juvenile individuals The major predators are birds but wasps and damselflies also prey upon smaller juveniles Nephila species are frequently parasitized by Argyrodes a genus of very small black and silver spiders that are kleptoparasitic As many as a few dozen may infest a single Nephila web to feed from the host spider s captured prey The frequent rebuilding or abandoning of webs by Nephila may be a tactic for controlling Argyrodes Spiny orb weaver spiders of the genus Gasteracantha also inhabit the webs of Nephila as kleptoparasites Egg sacs generally remain free from both predation and parasitism often due to the close proximity of the mother and how well it is hidden Life cycle editSpiderlings edit Nephila spiderlings leave the egg sac as a result of environmental cues often warmer and wetter conditions in spring They then live on a communal web eating dead siblings and web debris for around a week before dispersing to make individual webs 12 Young spiders do not generally build yellow colored silk and the young themselves can be easily mistaken for young orchard spiders Leucauge in general color and shape both genera sport silver stripes or patches on their abdomens described in some references as a form of heat control The best distinction between Leucauge and Nephila juveniles is web structure Leucauge species tend to build horizontal orbs that form a perfect circle whereas Nephila species build vertical elliptical orbs that are incomplete missing the portion of the orb over the hub the center where the spider sits The latter seem to prefer more open habitat such as second growth scrub or forest edges Fences or building overhangs often do just as nicely Molting and growth edit Once they are juvenile Nephila spiders inhabit their individual webs then begin their growth by the molting process The time between molts is called an instar and seven to 12 of these can occur depending on food availability Ecdysis the shedding of the exoskeleton occurs through the formation of a soft exoskeleton inside the current one Once the old exoskeleton is shed the new larger one begins to harden Ecdysis occurs when the spider s mass becomes too great for the current exoskeleton to support 25 Male spiders seek out females for copulation and live on their webs When mating season arrives both males and females stop molting and remain the same size for the remainder of their lives Venom editThe venom of the golden silk orb weaver is effective in action on prey but has not been reported to be of any notable consequence for humans if accidentally bitten In the literature Nephila is one of several genera where the venom must be considered as more or less ineffectual in human beings 26 That said the potentially large size of several members of the genus means that they possess relatively strong chelicerae so any bite can cause some mechanical damage but only of short term localised effect for humans However further studies of the venom components are needed to better understand pathways associated with any toxicity Interaction with humans editNephila do not seem to form either beneficial or harmful relationships with humans Females often construct their webs using human structures as a base for support strands due to their stability Individuals are often found in urban and suburban environments due to the protection from predation and greater prey availability 27 As they weave their webs in bushes and near flowers they might present a nuisance for gardeners or flower pickers Some nests near fruits may repel or destroy known pests such as Tephritid fruit flies without the need to use insecticides Spiders may bite humans if provoked but more often flee if confronted Golden silk edit nbsp Cape made from Madagascar golden orb weaver spider silk Victoria and Albert Museum London 28 There have been several efforts in the past to produce garments from Nephila silk although none commercially viable 29 These include two bed hangings that were shown at the 1900 Paris Exhibition 30 In 2004 a textile designer Simon Peers and an entrepreneur Nicholas Godley managed in three years work and using 1 2 million Golden silk orb weavers collected in the wild and released some 30 minutes later after they produced the silk to produce a shawl that was exhibited at the American Museum of Natural History in 2009 31 32 By 2012 they managed to produce a second bigger garment a cape that together with the shawl were exhibited at the Victoria and Albert Museum in London 33 Two shawls and a traditional Madagascan lamba made of this spider silk were included in an exhibition of curios from the natural world in 2021 34 Another possible use of Nephila silk lies in tissue engineering A study from the Medizinische Hochschule Hannover reports that processed Nephila silk is an excellent scaffold material thanks to its biocompatibility mechanical strengths and its property to promote cell adhesion and proliferation clarification needed 35 In particular the silk acts as a suitable guiding material for peripheral nerve regrowth 36 Fishermen on the coasts of the Indo Pacific ocean remove Nephila webs and form them into a ball which is thrown into the water There it unfolds and is used to catch bait fish 29 References edit a b c d Gen Nephila Leach 1815 World Spider Catalog Natural History Museum Bern Retrieved 2017 05 13 Cameron H D 2005 Chapter 73 An etymological dictionary of North American spider genus names In Ubick Darrell Paquin Pierre Cushing Paula E et al eds Spiders of North America An identification manual American Arachnological Society ISBN 9780977143900 OCLC 502287303 Serenc Michael 19 April 2012 Cairns man Ant Hadleigh snaps incredible pics of snake eating spider The Cairns Post Archived from the original on 21 April 2012 Retrieved 17 August 2012 Gallagher Terry Giant gentle spiders collected in Taiwan for study at U M Dearborn The University Record Online University of Michigan Retrieved 17 August 2012 Thompson Helen August 20 2014 Friendly Neighborhood Spiders Get Bigger in Cities Smithsonian Retrieved August 21 2014 Matjaz Kuntner Hamilton Chris A Cheng Ren Chung 2018 12 04 Golden Orbweavers Ignore Biological Rules Phylogenomic and Comparative Analyses Unravel a Complex Evolution of Sexual Size Dimorphism Systematic Biology 68 4 555 572 doi 10 1093 sysbio syy082 PMC 6568015 PMID 30517732 Retrieved 23 October 2021 Sankaran Pradeep 2020 06 04 On a new synonymy in the spider genus Nephila Leach 1815 Araneidae Nephilinae from India with supplementary notes on colour polymorphism in the genus Zootaxa 4786 4 4 Jun 2020 594 doi 10 11646 zootaxa 4786 4 11 PMID 33056468 S2CID 219923219 Retrieved 23 October 2021 Yuan Tao Zhang Zhisheng 2020 12 04 Molecular evidence that Trichonephila antipodiana and Nephila laurinae may be the same species Acta Arachnida 29 2 120 doi 10 3969 j issn 1005 9628 2020 02 010 Retrieved 23 October 2021 Selden Paul A Ren Dong November 2017 A review of Burmese amber arachnids Journal of Arachnology 45 3 324 343 doi 10 1636 JoA S 17 029 ISSN 0161 8202 S2CID 90983791 Turk Eva Candek Klemen Kralj Fiser Simona Kuntner Matjaz June 2020 Biogeographical history of golden orbweavers Chronology of a global conquest Journal of Biogeography 47 6 1333 1344 Bibcode 2020JBiog 47 1333T doi 10 1111 jbi 13838 ISSN 0305 0270 S2CID 218778879 Sivignon Cherie 19 March 2016 Giant spider feast for moreport The Press p A18 Retrieved 19 March 2016 a b Higgins L 2017 Nephila Life Cycle online Uvm edu Available at http www uvm edu lehiggin LifeCycle html Accessed 30 May 2017 a b c d Harvey Mark S Austin Andrew D Adams Mark 2007 The systematics and biology of the spider genus Nephila Araneae Nephilidae in the Australasian region Invertebrate Systematics 21 5 407 doi 10 1071 is05016 ISSN 1445 5226 Hsiung Bor Kai Justyn Nicholas M Blackledge Todd A Shawkey Matthew D 2017 06 01 Spiders have rich pigmentary and structural colour palettes Journal of Experimental Biology 220 11 1975 1983 doi 10 1242 jeb 156083 PMID 28566355 Phillips Campbell 23 November 2011 Golden orb web spider spins ant repellent silk Australian Geographic Retrieved 16 August 2012 Blackledge T 2011 Prey capture in orb weaving spiders are we using the best metric Journal of Arachnology 39 2 205 210 doi 10 1636 chi10 52 1 S2CID 54578394 Champion de Crespigny F Herberstein M Elgar M 2001 Food caching in orb web spiders Araneae Araneoidea Naturwissenschaften 88 1 42 45 Bibcode 2001NW 88 42C doi 10 1007 s001140000194 PMID 11261355 S2CID 21994595 a b Robinson M and Robinson B 1973 Ecology and behavior of the giant wood spider Nephila maculata Fabricius in New Guinea Smithsonian Contributions to Zoology 149 pp 1 76 Coddington Jonathan Hormiga G Scharff N 1997 Giant female or dwarf male spiders Nature 385 6618 687 688 Bibcode 1997Natur 385 687C doi 10 1038 385687a0 S2CID 4308746 Kuntner Matjaz Kralj Fiser S Schneider Jutta Li Daiqin 2009 Mate Plugging Via Genital Mutilation In Nephilid Spiders An Evolutionary Hypothesis Journal of Zoology 277 4 257 266 doi 10 1111 j 1469 7998 2008 00533 x Kuntner Matjaz Zhang Shichang Gregoric Matjaz Li Daiqin 2012 Nephila Female Gigantism Attained through Post maturity Molting Journal of Arachnology 40 3 345 347 doi 10 1636 b12 03 1 S2CID 30430184 Smith R 1984 Sperm Competition and the Evolution of Animal Mating systems 1st ed Elsevier pp 223 250 Fromhage L Schneider J 2004 Safer sex with feeding females sexual conflict in a cannibalistic spider Behavioral Ecology 16 2 377 382 doi 10 1093 beheco ari011 Humphreys W F 1993 Criteria for identifying thermal behaviour in spiders a low technology approach Memoirs of the Queensland Museum 33 543 550 Higgins L 2017 Summer Growth by Molting uvm edu The University of Vermont Bucherl W Buckley E E 1971 Venomous Animals and Their Venoms Volume III Venomous Invertebrates Academic Press p 562 Australian Geographic August 2014 Spiders in the city are bigger Kennedy Maev 24 January 2012 Spider silk cape goes on show at V amp A The Guardian London Retrieved 17 August 2012 a b Heimer S 1988 Wunderbare Welt der Spinnen Urania p 14 Spider silk at the V amp A A tangled and exquisite web they wove The Economist economist com 25 January 2012 Retrieved 18 August 2012 1900 Paris Exhibition Leggett Hadley 23 September 2009 1 Million Spiders Make Golden Silk for Rare Cloth Wired Science Retrieved 17 August 2012 American Museum of Natural History 24 September 2009 Rare Spider Silk on Exhibit at AMNH YouTube com Archived from the original on 2021 12 21 Retrieved 17 August 2012 Spider silk at the V amp A A tangled and exquisite web they wove The Economist economist com 25 January 2012 Retrieved 18 August 2012 Simon Peers a textile designer and Nicholas Godley an entrepreneur Eight years and 2m arachnids later spider silk fabrics go on show in London the Guardian 2021 09 06 Retrieved 2021 09 21 Biocompatible matrix for tissue engineering and wound dressing 2010 07 19 Retrieved 2011 02 23 Tissue Engineering peripherer Nerven mit Spinnenseide Peripheral nervous tissue engineering with spider silk in German Hannover Klinik fur Plastische Hand und Wiederherstellungschirurgie der Medizinischen Hochschule Hannover Archived from the original on 3 December 2012 Retrieved 17 August 2012 External links edit nbsp Data related to Nephila at Wikispecies nbsp Media related to Nephila at Wikimedia Commons Pictures of golden silk orb weavers A Golden Spider Silk Textile at the Art Institute of Chicago on YouTube Retrieved from https en wikipedia org w index php title Nephila amp oldid 1221105468, wikipedia, wiki, book, books, library,

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