Silk spiders (genus)

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Silk spiders
Silk spider (Nephila sp.)

Silk spider ( Nephila sp.)

Systematics
Class : Arachnids (arachnida)
Order : Spiders (Araneae)
Subordination : Real spiders (Araneomorphae)
Superfamily : Orb web spiders (Araneoidea)
Family : Silk spiders (Nephilidae)
Genre : Silk spiders
Scientific name
Nephila
Leach , 1815

The silk spiders ( Nephila ) are a genus of tropical and subtropical true spiders from the family of the silk spiders (Nephilidae) and comprise 23 species . (As of June 2016)

Occasionally they are golden orb weavers ( Engl . Golden (silk) orb-weavers ) called. They got their English name silk spider because of their fine but stable threads, the manufacture of which is also the subject of research. The spinning apparatus is located in the conical abdomen, which is partly brightly patterned. In the female animals it contains six different types of spinneret glands . The spiders are long-legged and 2 to 6 cm tall.

Net construction, behavior and catching prey

Silk spiders weave very large and stable spider webs , in which the lower half is clearly more pronounced. The catch spiral runs like a pendulum from one side to the other. Only the auxiliary spiral goes around the entire circle. Over the hub, the seat of the spider, they weave a curved sun protection for thermoregulation , the so-called barrier web , which is also seen as a modification of the so-called stabiliment. The thread of the silk spider shows a characteristic golden shimmer, especially when exposed to sunlight.

When exposed to direct sunlight, the spiders also change their posture and align themselves lengthways to the incident sun rays, so that the exposed area is smaller. It is possible that the guanine deposits , which create the conspicuous patterns on the abdomen, offer thermal protection through reflection . When the heat rises, silk spiders retreat to the shade of their sun protection. At over 40 ° C, a kind of anesthetic condition, the heat tupor, occurs. When it is cold, the body is aligned perpendicular to the sun's rays, so that the body surface can catch as much sun rays as possible, which increases the body temperature.

The silk spiders mainly catch their prey with their large webs. If an animal of the appropriate size gets caught in it, they first spin it briefly and then bite to inject their venom through the chelicerae . The prey is then transported to the hub and completely spun in. Finally it is removed from the net to eat. This is time-consuming, but makes the safe transport of larger animals possible. With their very solid webs, these spiders can even prey on small birds, which has been documented with photos in Australia.

Systematics and distribution

Nephila clavipes
Nephila inaurata
Silk spider ( Nephila sp.)

Between 1990 and 2006, the genus Nephila Leach , in 1815, belonged to the family of the real orb web spiders (Araneidae). In 2006, the World Spider Catalog took over the classification into the revised family of silk spiders (Nephilidae) based on the argumentation of Matjaž Kuntner . The genera Nephilengys L. Koch , 1872 and Nephilingis Kuntner , 2013 contain other species that were previously included in the genus Nephila .

The genus of the silk spiders comprises 23 species, some with several subspecies: (as of June 2016)

Fossil finds

A 165 million year old female specimen of a silk spider from the Jurassic was found in China . The silk spider called Nephila jurassica has a leg span of 15 cm, making it one of the largest fossil spiders discovered to date.

Web links

Commons : Silk Spiders ( Nephila )  - Album with pictures, videos and audio files

Nephila in the World Spider Catalog

literature

  • Rainer F. Foelix: Biology of the spiders. Georg Thieme Verlag, Stuttgart 1979, ISBN 3-13-575801-X .

Individual evidence

  1. ↑ a b Natural History Museum of the Burgergemeinde Bern: World Spider Catalog Version 17.0 - Nephila . Retrieved June 13, 2016.
  2. ↑ Giant spider eating a bird caught on camera. In: The Telegraph. Oct 22, 2008. (English)
  3. ↑ M. Kuntner: Phylogenetic systematics of the Gondwanan nephilid spider lineage Clitaetrinae (Araneae, Nephilidae). In: Zoologica Scripta. 35 (1), 2006, pp. 19-62. (PDF)
  4. ↑ Jonathan Amos: Fossilized spider 'biggest on record'. BBC World, April 20, 2011, accessed April 20, 2011 .