Nephila pilipes
| Nephila pilipes | ||||||||||||
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Nephila pilipes , older female without stripes |
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| Scientific name | ||||||||||||
| Nephila pilipes | ||||||||||||
| ( Fabricius , 1793) |
Nephila pilipes is a species from the genus of the silk spiders ( Nephila ). There are two subspecies. The distribution area of the nominate form N. pilipes pilipes extends from China over the Philippines to Australia . The subspecies N. p. malagassa is exclusively endemic to Madagascar . The species is one of the largest silk spiders and is also used as a farm animal. Above all, the nets are used as fishing nets and their meat as food.
features
This species of spider is one of the largest non- tarantula spider species in the world. The females are believed to be three to five centimeters long. The body length of an adult female documented by Michael H. Robinson and Barbara Robinson was 4.21 centimeters, the cephalothorax length was 1.41 centimeters. The length of one leg of the first pair of legs was determined to be 8.6 centimeters and the length of one leg of the fourth pair of legs was 7.05 centimeters. The males are comparatively tiny and on average probably 0.5 centimeters long. The largest body length documented by Michael H. Robinson and Barbara Robinson of a male was 0.76 centimeters.
Females have an elongated abdomen ( opisthosoma ), which is colored very differently depending on age and size. This is possibly also the reason why there are many synonyms for this species of spider. The opisthosoma is black to olive-colored at a younger age and has two or four yellow vertical stripes, depending on its size. First, the outer two longitudinal stripes recede and with increasing age the inner two longitudinal stripes recede. With increasing age and size, the abdomen is almost uniformly gray-brown to olive in color; only in the anterior half near the fore-body ( prosoma ) does the opisthosoma have a black transverse bar, where remnants of the yellow longitudinal stripes can often be seen as fine yellow transverse stripes. The regression of these streaks can take place at different speeds depending on the individual. So you can find younger animals that only have two yellow vertical stripes and older ones that still have all four vertical stripes. The underside has several yellow spots, only the region of the spinnerets is colored red.
The prosoma is bright white, silver to beige in color. The buttons are strikingly orange to red in color, only the metatarsus is two-tone yellow-black and the tarsus is black. The color of the legs varies depending on where they were found and how old they were: In the very elongated legs, depending on where they were found, the coxa is yellow and the thigh ring ( trochanter ) is black. The femur is black with a yellow spot on the underside at the beginning and end. The patellae are black in color with a narrow yellow spot on the underside at the transition to the tibia . The tibia is also colored black and has a yellow spot on the underside at the transition to the metatarsus. Metatarsi and tarsi are uniformly black. There are specimens with reddish legs with black hollows of the knees, where these yellow areas are missing. The sternum is black.
behavior
Reproduction
In the network of the female, there are very often several males who try to mate with the female at the same time. The males interact with each other by fighting with their legs and biting each other when they come too close. Only the victorious male mates with the female. To do this, the male climbs on the underside of the female's abdomen and pumps his semen from his bulbs into the female's genital opening. This process takes a relatively long time. Mating times of ten to seventy minutes were measured. The female has never been observed to eat the male after mating. The male leaves the female after mating.
To lay eggs, the female builds a cocoon about 5 centimeters long. The average measured was between 2000 and 3000 eggs with an average total weight of around 1.2 grams.
Network construction
The female spider builds webs with a diameter of 0.6 to 1.0 meters. Male spiders do not build webs, but live in a female's web and feed on insects that are too small for the female and on what remains of the female's prey.
Protection against overheating
Similar to the golden silk spider, the spider protects itself from overheating. To do this, she stretches her abdomen towards the sun, which increases the angle of the sun's rays. Liquid is also processed in the chelicerae , which also provides cooling.
Enemies and parasites
There are often up to forty thief spiders of the genus Argyrodes in the webs . These are small spiders that steal part of the prey from the silk spider.
It was investigated why the spiders in nature are not eaten by birds; under laboratory conditions, many birds ate the spiders. The laboratory birds tried only once to eat a spider in Nephila's web . The reason lies in the sticky webs of the silk spiders, which also serve as protection from birds. Once a bird has flown into a net, a large piece of net gets stuck to the bird's body and the bird takes a long time to free its plumage. Birds that have once had this experience will shy away from silk spider webs in the future.
The spider as a farm animal
The females of Nephila pilipes are used as fishing net makers in the South Pacific . Bamboo tubes are set up as a frame and the spider makes its net in this frame, which is later used for fishing.
The natives eat the female spiders raw or roasted as a protein supplement.
Synonyms
Since this spider species has a different body color depending on where it was found, size and age, it has been taxonomically recorded several times . According to Platnick, there are several synonyms. The best known synonym is Nephila maculata .
Web links
Nephila pilipes in the World Spider Catalog
Individual evidence
- ↑ a b N. I. Platnick: http://research.amnh.org/entomology/spiders/catalog/NEPHILIDAE.html Status 2008. The world spider catalog, version 8.0. American Museum of Natural History
- ↑ a b c d University of Florida Institute of Food and Agriculture Sciences: golden silk spider (accessed October 28, 2007)
- ↑ a b c d e f g h Michael H. Robinson and Barbara Robinson, The Ecology and Behavior of Nephila maculata: A Supplement , Smithsonian contributions to zoology, Number 218, Smithsonian Institution Press, City of Washington, 1967
- ↑ a b c d e W. Rea Sherriffs, Hong Kong Spiders , in: The Hong Kong Naturalist, June 1934 ( PDF )
- ^ Friedrich Dahl , Seidenspinne und Spinnenseide , in: Mitteilungen aus dem Zoologischer Museum in Berlin, Berlin 1912