Bigeye spider
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Bigeye spider ( Deinopis subrufa ), female |
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| Deinopis subrufa | ||||||||||||
| L. Koch , 1879 |
The bigeye spider ( Deinopis subrufa ) is a web spider from the family of landing net spiders (Deinopidae). Like all species of this family, of which it is the best-known representative, the bigeye spider is known for its extraordinary catching technique for prey.
features
The bigeye spider reaches a leg span of 60 millimeters and a body length of up to 25 millimeters, whereby the males usually remain somewhat smaller (10 to 15 millimeters body length). Another gender dimorphism , in addition to the different size and body shape, is the color. The female is red-brown throughout, while the slightly slimmer male has a gray-brown basic color and several dark stripes on the prosoma , opisthosoma and legs. It also has two small white appendages above the eyes. The bigeye spider has a narrow body, the opisthosoma, in contrast to that of other web spiders, is slimmer than the prosoma. and extremely long and thin legs, which gives it good camouflage ability. In order to be able to perceive prey without problems at night, the big-eye spider has two particularly noticeably large and frontally arranged main eyes among the eight well-developed eyes. In addition, it has six smaller secondary eyes distributed on the flanks of the prosoma. The light intensity of the eyes is F 0.58 higher than that of the eyes of other nocturnal animals such as owls or cats . The large retinal membrane of the eyes, which is renewed every night, picks up the visual images of the eyes.
Occurrence
The bigeye spider is endemic to Australia . Their preferred distribution area are the eastern states of Queensland , New South Wales , Victoria and the island of Tasmania . Their preferred habitats are forests, scrub and heaths. The spider can also be found in gardens. The species is common in its range.
Way of life
Catching prey
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The German-speaking common name of the Deinopinae, to which the bigeye spider belongs, is landing net spinning. They are named after the landing net , a bag-like net that is used to catch fish or insects. The bigeye spider, like all net spiders, builds a rectangular safety net the size of a postage stamp, which is held in place with the two front pairs of legs. With the two rear pairs of legs, the spider seeks hold on the construction threads of the web. It assumes a characteristic catching position (see graphic). The square and central catching area of the net consists of coarse-meshed catching threads that are evenly laid out one behind the other. The web is provided with white excretions from the spider's body, which are used for marking. The net is placed close to the ground and anchored to leaves, twigs or bark. There the spider waits motionless in its lurking position until a suitable prey object gets under the web. If it gets into the area of the marking, the spider expands the safety net by spreading its legs to three times its size and throws it precisely at the prey. Both processes take place at the same time in a flash. Then the prey is put out of action with a poison bite and then spun in. The spider immediately devotes itself to feeding in the remains of the now destroyed web. Sometimes a new safety net is already spun while eating. Various migratory arthropods , such as ants, cockroaches or other spiders, are mainly used as prey . With its trapping method, the bigeye spider can also hunt larger and well-fortified prey, and the successful trapping of male trapdoor spiders has also been observed. It is also possible to capture flight-capable or agile prey with quick reactions, such as crickets or moths . During the day, the spider remains mostly motionless in its web and lays its legs together so that its visual appearance and color give the impression of a branch and thus remains camouflaged.
Reproduction
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The bigeye spider reaches sexual maturity in summer, but mating does not take place until autumn. If a male has found a female, it spins a thread on one of the construction threads from the female's net and provides it with sperm droplets and tries to lure it onto this thread by plucking it. After mating, the male dies and the female begins to produce a light brown and round cocoon with a diameter of nine to ten millimeters some time afterwards. A cocoon contains 100 to 200 eggs and can be made in numbers of up to four by a pregnant female. The cocoons are camouflaged with plant particles. The females do not care for the brood. The eggs overwinter and the young spiders hatch in spring and use the remains of the cocoon as their first source of food. After a few weeks, the young spiders leave their hiding place and begin to create nets like the adult spider. The still immature spiders then grow until summer.
Systematics and taxonomy
The bigeye spider was in 1879 by Ludwig Carl Christian Koch originally called subrufus Dinopis first described . The spelling of ancient Greek δεινός ( deinós 'terrible, mighty' ) in the transcription “Dino-” was common at that time (see dinosaurs ), but was later changed to the original generic name Deinopis MacLeay, 1839, and the grammatical gender of the species name subrufa customized. L. Koch's extensive German-language work The Arachnids of Australia described and depicted from nature was published in successive individual deliveries from 1871 onwards. In this work Koch not only described a female of Deinopis subrufa , but a few pages later a similar Deinopis species, to which he gave the name Deinopis bicornis (from Latin bicornis , two-horned ). Later, however, it turned out that it was the male of the bigeye spider, which, unlike the female, has two small white appendages above the eyes. Since then, Deinopis bicornis has been a synonym for Deinopis subrufa .
gallery
Distribution area of the bigeye spider
A female a day in her web without a safety net
Males in size comparison
Top view of a male
Frontal view of a male
Detail of a male with a clearly visible bulb
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Individual evidence
- ↑ Description of the bigeye spider on www.ozanimals.com ( [1] Link)
- ↑ a b c d e description of the bigeye spider on bie.ala.org.au ( Link )
- ↑ a b c d e f g h Description of the bigeye spider on australianmuseum.net.au ( Link )
- ↑ L. Koch : Dinopis subrufus nov. spec. In: The arachnids of Australia described and illustrated from nature . 23. Delivery, published by Bauer & Raspe, Nuremberg 1879, p. 1039.
- ↑ L. Koch: Dinopis bicornis nov. spec. In: The arachnids of Australia described and illustrated from nature . 24. Delivery, published by Bauer & Raspe, Nuremberg 1879, p. 1049.
literature
- L. Koch : Dinopis subrufus nov. spec. In: The arachnids of Australia described and illustrated from nature . 23. Delivery, Verlag von Bauer & Raspe, Nuremberg 1879, p. 1039. (First description, German)
