Big angle spider
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Large angle spider ( Eratigena atrica ) |
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| Eratigena atrica | ||||||||||||
| ( CL Koch , 1843) |
The large angle spider ( Eratigena atrica , syn .: Tegenaria atrica ), also called " house spider ", is one of at least eight species of the genus of the angle spiders ( Eratigena ) native to Central Europe and the largest native spider species here . It was Spider of the Year 2008 and is also known as the angle spider or house angle spider , but these names are ambiguous.
The German common name " house spider " is commonly used for many spiders of the genus Eratigena and related genera (e.g. Tegenaria ), which are also often found in houses. In addition to the large angle spider, these are:
- the house corner spider ( Tegenaria domestica , syn .: T. derhami and T. domesticus ),
- the wall angle spider ( Tegenaria parietina )
- and the rust-red angle spider ( Tegenaria ferruginea , Syn .: Malthonica ferruginea )
The large angle spider Eratigena atrica can easily be confused with other species of the genus. A reliable, quick distinguishing feature from other Eratigena species are the monochrome legs that only Eratigena atrica , the smaller Eratigena picta and the darker field-angle spider Eratigena agrestis have. The drawing of the sternum or even the inner structure of the pedipalps (males) or the epigynees (females) should be used for reliable differentiation .
Habitat and Distribution
The great angle spider is native to all of Europe, Central Asia and North Africa and was introduced to North America, where it established itself. In the temperate zone it inhabits protected and dry areas up to 800 m altitude, and much less often above.
It has its habitat mainly in caves, in dry, dry, warm deciduous forests , in tree hollows or tunnels and in buildings, in vineyards, hedges and bushes and ruderal locations , but always close to the ground, less often in the shrub layer; it avoids moist habitats. The troglophile large angle spider often stays close to humans, in basements, in apartments such as barns or sheds in hard-to-reach and dark corners that are undisturbed for a long time. In human dwellings, their worst enemy - apart from humans themselves - is the great trembling spider , which, thanks to its special catching technique, can also capture much larger angle spiders. Also Klebfadenweber it can be dangerous.
anatomy
The body of the house spider Eratigena atrica is between 14 mm (males) and 18 (to 20) mm (females) in size. Males and females do not differ in basic coloring or drawing. The basic color is dark brown. On the breast plate ( sternum ) the large angle spider has a club-shaped light brown markings, with the narrow end of the club pointing towards the abdomen. To the side of this time are three light brown spots that get smaller from front to back and are arranged in such a way that they converge in rays.
Large angle spider (female, front view)
E. atrica - females eating nocturnal prey
The abdomen has a narrow, light central stripe that extends from the front to the middle. To the side of it you can see six “corner spots”, some of which also run with the median. That sits at the bottom of the abdomen at the back of the anal opening, behind spinnerets . Further forward, on the underside of the abdomen, it has breathing slits and the genital pore . The house spider Eratigena atrica and Eratigena picta differs from other species of the genus Eratigena , which usually have curled or spotted legs, with their monochrome, light brown, bristly and finely hairy legs . The front pair of legs is the longest, the length of the legs decreases towards the back.
The single-colored brown legs, with only the last limbs slightly bristled, reach twice the body length of the female and three times the body length of the male. This running apparatus enables them, like all types of Eratigena , to achieve considerable speeds (up to 50 cm / s), which, however, cannot be maintained for long. Two of the spider's leg joints are hydraulic. The pressure to stretch is generated in the front part of the abdomen (prosoma). The legs are also not suitable for climbing, so vessels with smooth walls often become a trap. Scopula hairs on the tarsus are different from those of other spiders and generate less adhesive force .
E. atrica - Dark pattern just before molting
Females after moulting, also showing the stripped exoskeleton
The bristles and hair on the legs and the fine hairs of the entire body are, as with all spiders, the most important sense organ, with which even the slightest vibrations and sound can be perceived; some of the lowest mechanical stimulus thresholds known from spiders could be measured in spiders of the genera Eratigena and Tegenaria . On the legs and pedipalps there are also chemosensors, which play an important role, especially in recognizing prey and in courtship. The nocturnal house spider Eratigena atrica has eight eyes of the same size, which are arranged in two rows one above the other to the front. Your sense of sight is probably limited to light-dark contrasts, as these are individual eyes with fewer than 400 visual cells.
Eratigena atrica belongs to the tribe of the arthropods (Arthropoda) and thus to the molting animals (Ecdysozoa). The spider sheds its skin several times up to its full size, and less often with increasing age. The entire skeleton is renewed and is a lot larger after the moult. Shortly before moulting, you can see a much darker black color. The breastplate bursts open and the spider winds its very soft body out of its tight old skin over a long period of time. Then it rests and the body hardens.
behavior
The house spider, which is mainly active in the late evening hours and at night, builds a funnel web in less disturbed places in the house, which tapers to a residential tube at the end. From the net she stretches catch threads in which prey animals get tangled. Since it does not produce any threads of glue, the prey is held down and, with its vertical chelicerae (jaw claws), is crushed to a pulp and taken up.
The animals only leave their network in the event of a disturbance, also depending on the weather, for example in the case of moisture or low temperatures or cold drafts in winter, but always return. If, on the other hand, there is no longer enough food in the area, or if the hiding place is destroyed, they start looking for a place for a new den. Sometimes abandoned nests are repopulated or those that are still inhabited are conquered. The spider also drives other house spiders out of their burrows or even kills them. Only the males go in the night hours in late summer and autumn on an extended search for females and are therefore more often found outside their hiding places during this time.
The house spider becomes two or three years old, in rare cases up to six years. Although feared by many, the spiders are harmless to humans.
Reproduction and development
The males are more common on forays, especially in late summer and early autumn, when they are looking for females willing to mate. You approach them with movements of the pedipalps (jaw sensors ) and the front pair of legs. If the female is not ready to mate, the male becomes a victim. The male must approach the female very carefully. The complicated pairing lasts for hours, with the couple pausing peacefully more often. The sex organs are located in an unfavorable place, namely on the anterior underside of the abdomen. During the mating season, the males can be easily recognized by their enlarged pedipalps.
Pedipalps of a male
Female with egg cocoon
Cub
Web links
- Eratigena atrica in the World Spider Catalog
- Tegenaria atrica in Fauna Europaea
- Spiders of Central Europe - online identification key
- Eratigena atrica in the Wiki of the Arachnological Society e. V.
- More pictures and information on "Nature in NRW"
literature
- Rainer f. Foelix: biology of the spiders. Thieme, Stuttgart 1979, ISBN 3-13-575801-X
- Ambros Hänggi, Edi Stöckli, Wolfgang Nentwig: Habitat of Central European Spiders . Miscellanea Faunistica Helvetiae 1995, Center suisse de cartographie de la faune, Neuchatel (CH).
- Frieder Sauer , Jörg Wunderlich: The most beautiful spiders in Europe . Fauna Verlag, Karlsfeld 1985.
- Dick Jones: The Cosmos Spider's Guide . Franckh, Stuttgart 1990, ISBN 3-440-06141-8
Individual evidence
- ↑ Natural History Museum of the Burgergemeinde Bern: World Spider Catalog Version 15.5 - Eratigena atrica . Retrieved September 5, 2014.
- ↑ Rainar Nitzsche : Spiders: Biology - Man and Spider - Fear and Toxicity. Books on Demand, 2018, ISBN 978-3-8370-3669-5 . P.56.