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Spinneret

From Wikipedia, the free encyclopedia
External body part of a spider
This article is about the spider or insect organ. For other uses, seeSpinneret (disambiguation).
The spinnerets of anAustralian garden orb weaver spider.
Black spinneret ofPhidippus adumbratus visible below red abdomen

Aspinneret is asilk-spinningorgan of aspider or thelarva of aninsect. Some adult insects also have spinnerets, such as those borne on the forelegs ofEmbioptera.[1] Spinnerets are usually on the underside of a spider'sopisthosoma, and are typically segmented.[2][3] While most spiders have six spinnerets, some have two, four, or eight.[4] They can move both independently and in concert.

Most spinnerets are not simple structures with a single orifice producing a single thread, but complex structures of many microscopic spigots, each producing one filament. This produces the necessary orientation of the protein molecules, without which the silk would be weak and useless. Spigots can be singular or found in groups, which also permits spiders to combine multiple filaments in different ways to produce many kinds of silk for various purposes. Spinneretmorphology can helparachnologists identify thetaxon of a specimen and the specific morphology of a spigot can determine its use as well. For example, flagelliform spigot is unique toAraneoidea, and another kind of spigot found in sets of three, referred to as cylindrical gland spots, are found only in females and used for making egg sacs.[5] The desert grass spider,Agelenopsis aperta, has especially prominent spinnerets that extend out of the end of their abdomen.[6]

Variousspecies of spiders use silk extruded from spinnerets to buildwebs, to transfer sperm, to entrap insects by wrapping it around them, to make egg-cases, to manipulate static electricity in the air, and to fly (ballooning), etc.

Some insect larvae (includingsilkworms) extrude silk to make a protectivecocoon for theirmetamorphosis. The insects known asweb spinners weave silken galleries for protection from predators and the elements while foraging and breeding.[7]

Evolution

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Observations suggesting that there might be silk-producing organs on the feet of the zebratarantula (Aphonopelma seemanni) led to questions about the origins of spinnerets. It was hypothesised that spinnerets in spiders were originally used as climbing aids on the feet and evolved and were used for webmaking at a later time.[8]

  • The compact spinnerets of Argiope bruennichi; placed ventrally below the posterior.
    The compact spinnerets ofArgiope bruennichi; placed ventrally below the posterior.
  • A barn spider encases her prey in silk emanating from her spinneret seen in the foreground.
    A barn spider encases her prey in silk emanating from her spinneret seen in the foreground.
  • Ventral aspect of spinnerets of spider species with unusually long spinnerets.
    Ventral aspect of spinnerets of spider species with unusually long spinnerets.

References

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  1. ^INSECTA: EMBIOPTERA (EMBIIDINA)Archived 2013-12-03 at theWayback Machine, Retrieved December 1, 2013
  2. ^Wiggins, Charlotte (Nov 10, 2013)."Gardening to Distraction: Along came a spider".The Rolla Daily News. Therolladailynews.com. RetrievedDecember 1, 2013.
  3. ^Pechmann, Matthias; Khadjeh, Sara; Sprenger, Frederik; Prpic, Nikola-Michael (2010). "Patterning mechanisms and morphological diversity of spider appendages and their importance for spider evolution".Arthropod Structure and Development.39 (6):453–467.doi:10.1016/j.asd.2010.07.007.PMID 20696272.
  4. ^Spider Identification – Types of Spiders, Retrieved December 1, 2013
  5. ^Coddington, Jonathan A. (Spring 1989)."Spinneret Silk Spigot Morphology: Evidence for the Monophyly of Orbweaving Spiders, Cyrtophorinae (Araneidae), and the Group Theridiidae Plus Nesticidae".The Journal of Arachnology.17 (1). American Arachological Society:71–95.JSTOR 3705406. Retrieved31 August 2020.
  6. ^Bradley, Richard A. (2012-12-18),"FAMILY CLUBIONIDAE • Sac Spiders",Common Spiders of North America, University of California Press, pp. 105–106,doi:10.1525/california/9780520274884.003.0014,ISBN 978-0-520-27488-4, retrieved2020-12-08
  7. ^Richards, O. W.; Davies, R.G. (1977).Imms' General Textbook of Entomology: Volume 1: Structure, Physiology and Development Volume 2: Classification and Biology. Berlin: Springer.ISBN 0-412-61390-5.
  8. ^Gorb, SN; Niederegger S; Hayashi CY; Summers AP; Votsch W; Walther P (September 28, 2006)."Bio materials: silk-like secretion from tarantula feet".Nature.443 (7110): 407.Bibcode:2006Natur.443..407G.doi:10.1038/443407a.PMID 17006505.S2CID 4415648.

External links

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