![](http://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Ballooning_spiderlings.jpg/220px-Ballooning_spiderlings.jpg)
Luftschiffen nennt man den Vorgang, bei dem sich Spinnen in die Luft erheben und fliegend mehrere hundert Kilometer zurücklegen können. Dies geschieht, indem die Spinne bei Wind mehrere Dutzend Seidenfäden produziert, welche dann mitsamt der Spinne davongetragen werden. Neueste Forschungen beschreiben ein ähnliches Verhalten auch bei Windstille, bei welcher die Spinnen elektrische Felder als Antriebsenergie nutzbar machen. Sinn und Zweck des Spinnenflugs sind bisher nicht vollständig geklärt.
Vorwiegend junge und sehr leichte Spinnen, aber auch die erwachsenen Exemplare der Baldachinspinne, starten ihren Flug von besonders exponierten Stellen. Sie beginnen wie auf Zehenspitzen zu trippeln und schießen dann aus ihren Spinnwarzen am Hinterleib ein ganzes Bündel von Fäden in die Luft, die sich wie eine Art Fächer aufspreizen. An diesem Gebilde hängend segeln die Tiere dann durch die Luft. Bei günstigem Wind können die Tiere sogar in den Jetstream gelangen und ganze Ozeane überqueren. Viele Spinnen überleben diese Reise allerdings nicht.
Beschreibung
BearbeitenDer Flug der Spinnen und anderer Wirbelloser beginnt meistens an Wind-exponierten Stellen, wo sich die Tiere strecken ("trippeln") und ein Gespinnst von 50-60 extrem leichten Seidenfäden spinnen und aussondern.[1] Dieses "Segel" kann sie bis zu mehreren Kilometern Höhe in die Luft und über sehr große Entfernungen davontragen. Dadurch waren sie etwa schon 1832 auf der Beagle von Charles Darwin gelandet, hundert Kilometer von der Küste Argentiniens.
These automatically form a triangular shaped parachute[1] which carries the spider away on updrafts of winds where even the slightest of breezes will disperse the arachnid.[2][1] The Earth's static electric field may also provide lift in windless conditions.[3] Ballooning behavior may be triggered by favorable electric fields.[4][5]
Many spiders use especially fine silk called gossamer[6] to lift themselves off a surface, and silk also may be used by a windblown spider to anchor itself to stop its journey.[1] The term "gossamer" is used metaphorically for any exceedingly fine thread or fabric. Biologists also apply the term "balloon silk" to the threads that mechanically lift and drag systems.Vorlage:Elucidate
It is generally thought that most spiders heavier than 1 mg are unlikely to use ballooning.[7] Because many individuals die during ballooning, it is less likely that adults will balloon compared to spiderlings. However, adult females of several social Stegodyphus species (S. dumicola and S. mimosarum) weighing more than 100 mg and with a body size of up to Vorlage:Convert have been observed ballooning using rising thermals on hot days without wind. These spiders use tens to hundreds of silk strands, which form a triangular sheet with a length and width of about Vorlage:Convert[1]
In Australia, in 2012 and in May 2015, millions of spiders were reported to have ballooned into the air, making the ground where they landed seem snow-covered with their silk.[8]
Distance and height achieved
BearbeitenMost ballooning journeys end after just a few meters of travel, although depending on the spider's mass and posture,[9] a spider might be taken up into a jet stream. The trajectory further depends on the convection air currents and the drag of the silk and parachute to float and travel high up into the upper atmosphere.[10]
Many sailors have reported spiders being caught in their ship's sails over Vorlage:Convert[11] from land (Heimer 1988). They have even been detected in atmospheric data balloons collecting air samples at slightly less than Vorlage:Convert above sea level.[12] Evidently, ballooning is the most common way for spiders to invade isolated islands and mountaintops.[11][13] Spiderlings are known to survive without food while travelling in air currents of jet streams for 25 days or longer.[14]
Some mites and some caterpillars also use silk to disperse through the air.Vorlage:Citation needed
A close association has been found between ballooning behaviors and the ability for a species of spiders to survive afloat on water. Water-repellent legs keep them alive on both fresh and salt water, enabling them to survive waves up to 0.5 metres in height. In wind many species raised their legs or abdomens to use as sails, propelling themselves across the water's surface. Many species of spiders also drop silk to anchor themselves in place while afloat. Said spiders did not show these behaviours on land, suggesting that they are adaptations to water.[15][16][17]Vorlage:Clear
See also
Bearbeiten- Aeroplankton
- "A Noiseless Patient Spider", a poem by Walt Whitman based on spider ballooning behaviour
- Organisms at high altitude
- Spider silk
References
BearbeitenFurther reading
Bearbeiten- Vorlage:Aut (1985): Size of ballooning spiders at two locations in eastern Texas. J. Arachnol. 13: 111–120. PDF
- Vorlage:Aut (1988): Wunderbare Welt der Spinnen. Urania-Verlag Leipzig. Vorlage:ISBN.
Vorlage:Kites Vorlage:Spider nav Vorlage:Ethology
Kategorie:Arachnology Kategorie:Kites Kategorie:Ethology Kategorie:Articles containing video clips Kategorie:Gliding animals
- ↑ a b c d J.M. Schneider, Roos, J., Lubin, Y., Henschel, J.R.: Dispersal of Stegodyphus Dumicola (Araneae, Eresidae): They do balloon after all! In: Journal of Arachnology. 29. Jahrgang, Nr. 1, Oktober 2001, S. 114–116, doi:10.1636/0161-8202(2001)029[0114:DOSDAE]2.0.CO;2 (americanarachnology.org [PDF; abgerufen am 18. Juli 2009]).
- ↑ G.S. Weyman: Laboratory studies of the factors stimulating ballooning behavior by Linyphiid spiders (Araneae, Linyphiidae). In: Journal of Arachnology. 23. Jahrgang, 1995, S. 75–84 (americanarachnology.org [PDF; abgerufen am 18. Juli 2009]).
- ↑ Vorlage:Cite arxiv
- ↑ Erica L. Morley, Daniel Robert: Electric Fields Elicit Ballooning in Spiders. In: Current Biology. 5. Juli 2018, doi:10.1016/j.cub.2018.05.057 (cell.com [abgerufen am 5. Juli 2018]).
- ↑ Ed Young: Spiders Can Fly Hundreds of Miles Using Electricity In: The Atlantic, 5 July 2018
- ↑ Oxford English Dictionary 2nd ed.: Gossamer, noun and adjective: fine filmy substance, consisting of cobwebs, spun by small spiders, which is seen floating in the air in calm weather, esp. in autumn, or spread over a grassy surface: occas. with a and pl., a thread or web of gossamer.
- ↑ Suter, R.B.: An aerial lottery: The physics of ballooning in a chaotic atmosphere. In: Journal of Arachnology. 27. Jahrgang, 1999, S. 281–293 (americanarachnology.org ( des vom 11. Februar 2006 im Internet Archive)).
- ↑ Christine Dell'Amore, National Geographic PUBLISHED May 18: Millions of Spiders Rain Down on Australia—Why? In: National Geographic News. Abgerufen am 19. Mai 2015.
- ↑ R.B. Suter: Ballooning: Data from spiders in freefall indicate the importance of posture. In: Journal of Arachnology. XX. Jahrgang, 1992, S. 107–113 (americanarachnology.org [PDF; abgerufen am 18. Juli 2009]).
- ↑ M.H. Greenstone, Morgan, C.E., Hultsh, A.-L.: Ballooning spiders in Missouri, USA, and New South Wales, Australia: Family and mass distributions. In: Journal of Arachnology. 15. Jahrgang, 1987, S. 163–170 (americanarachnology.org [PDF; abgerufen am 18. Juli 2009]).
- ↑ a b G. Hormiga: Orsonwells, a new genus of giant linyphild spiders (Araneae) from the Hawaiian Islands. In: Invertebrate Systematics. 16. Jahrgang, Nr. 3, 2002, S. 369–448, doi:10.1071/IT01026 (gwu.edu [PDF; abgerufen am 18. Juli 2009]).
- ↑ J.K. VanDyk: Entomology 201 - Introduction to insects. Department of Entomology, Iowa State University, archiviert vom am 8. Juni 2009; abgerufen am 18. Juli 2009.
- ↑ S.W. Bilsing: Quantitative studies in the food of spiders. In: The Ohio Journal of Science. 20. Jahrgang, Nr. 7, Mai 1920, S. 215–260 (osu.edu [PDF; abgerufen am 18. Juli 2009]).
- ↑ C.E. Valerio: Population structure in the spider Achaearranea Tepidariorum (Aranae, Theridiidae). In: Journal of Arachnology. 3. Jahrgang, 1977, S. 185–190 (fms.holycross.edu ( des vom July 19, 2011 im Internet Archive) [abgerufen am 18. Juli 2009]).
- ↑ Morito Hayashi, Mohammed Bakkali, Alexander Hyde, Sara L. Goodacre: Sail or sink: novel behavioural adaptations on water in aerially dispersing species. In: BMC Evolutionary Biology. 15. Jahrgang, Nr. 1, 3. Juli 2015, ISSN 1471-2148, S. 118, doi:10.1186/s12862-015-0402-5, PMID 26138616, PMC 4490750 (freier Volltext) – (englisch, biomedcentral.com).
- ↑ Daniel Cressey: Airborne Spiders Can Sail on Seas.
- ↑ Flying spiders also sail on water. In: Nature. 523. Jahrgang, S. 130–131, doi:10.1038/523130d, bibcode:2015Natur.523T.130. (nature.com [abgerufen am 9. Juli 2015]).