Steatoda nobilis
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| Steatoda nobilis (Thorell, 1875) |
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Steatoda nobilis, commonly known in England as the biting spider or the false black widow (though several other species are known by the latter name), is a common species of spider in the genus Steatoda. As one of this spider's common name indicates, the spider superficially resembles, and is frequently confused for, the black widow and other venomous spiders in the genus Latrodectus. The spider is native to the Canary Islands but arrived in England in around 1870 through bananas sent to Torquay.[1] In England it has a reputation as one of the few local spider species which will readily bite humans.
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[edit] Description
Like true widow spiders, S. nobilis has a round, bulbous, over-sized abdomen, which is darkly colored. Females typically have pale markings on the dorsal side of the abdomen, with a cream-coloured band. Full-size females range in size from 7mm to 14mm.
[edit] Habitat and range
In common with other members of the Theridiidae family, S. nobilis constructs a cobweb, i.e., an irregular tangle of sticky silken fibers. As with other web-weavers, these spiders have very poor eyesight and depend mostly on vibrations reaching them through their webs to orient themselves to prey or warn them of larger animals that could injure or kill them.
[edit] Distribution
The spider is found in the Canary Islands, in England (Corwall, Dorset and Essex)[2], and in Madeira; it has also been observed in parts of continental Europe and Africa. [3].
[edit] Medical significance
They are not aggressive, and most injuries to humans are due to defensive bites delivered when a spider gets unintentionally squeezed or pinched somehow. It is possible that some bites may result when a spider mistakes a finger thrust into its web for its normal prey, but ordinarily intrusion by any large creature will cause these spiders to flee.
The bite of S. nobilis is known to be medically significant in humans, however without any long-lasting effects. The bite of this spider, along with others in the genus Steatoda, can produce a set of symptoms known as steatodism. Symptoms of bites include intense pain radiating from the bite site, along with feverishness or general malaise. [4] In 2006 a Dorchester man spent three days in Dorchester County Hospital with symptoms of heart seizure, after suffering a spider bite believed to be caused by S. nobilis. (A spider was observed in the act of biting the man; however it was not captured and positively identified by an expert).[1]
The bite of S. nobilis, like other Steatoda spiders is far less dangerous to humans than that of true black widows.
[edit] References
- ^ a b David Sapsted. "Watch out, the black widow's sister is ready to bite you"", Daily Telegraph, 2006-11-17.
- ^ Biting spider widens its web (HTML). BBC News: news.bbc.co.uk (November 2006). Retrieved on November 18, 2006.
- ^ http://www.britishspiders.org.uk/html/bas.php?page=world&taxon_key=NBNSYS0000039460 British Agricultural Society: World Distribution Map of S. Nobilis
- ^ http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1801319&dopt=Abstract
[edit] External links
