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Tuesday, February 7, 2012

Black Window Spider

Beauty Of Animal | Black Window Spider | Black Window spider is a species of spider in the family Theridiidae, that contains 31 recognized species. The Black Widows are perhaps the best known representatives of the genus. The injection of neurotoxic poison latrotoxin of this type is a comparatively dangerous spider bite, what latrodectism in the state, named for the genus. The female black widow's bite is especially dangerous for humans because of its unusually large poison glands, but Latrodectus bites rarely kill people, when their wounds are given medical treatment.
The prevalence of sexual cannibalism in Latrodectus of a female spider had given them the common name "Black Widow". The female Latrodectus most of the time eat their males after mating partners Latrodectus. Not all adult female black widows show the red hourglass on the ventral or underside of the abdomen, some have a pair of red spots or no labeling at all. Female widows often show distinct red markings on the back or top of the abdomen, commonly two red spots.  
The bite of a male black widow is not considered dangerous to humans, it is the bite of adult female black widow venom sacs from their much larger that this spider has given its dangerous reputation. Although there are large differences in detail on the type and sex, each spider is a red hourglass or a pair of large, red, round spots on the ventral abdomen shows an otherwise black, shiny body an adult female black widow.
Spiders of the genus Steatoda (also of Theridiidae family) are often mistaken for widows, and are known as "false widow", they are much less harmful to humans. Together with other members of the family Theridiidae, the widow spiders construct a network of irregular, tangled, sticky silken fibers. Then, before the insect can liberate themselves, the spider rushes over to bite it and wrap it in silk. The southern black widow, as well as the closely related western and northern species, so far as the same species has a distinctive red hourglass figure on the underside of its abdomen. Many of the other widows have red pattern on a glossy black or dark background, which serve as a warning.
Widows can be found on all continents of the world except Antarctica. In North America, the black widows commonly referred to as southern (Latrodectus mactans) is Western (Latrodectus Hesperus) and northern (Latrodectus variolus) found known in the United States, as well as the "gray" or "black widow" (Latrodectus geometricus) and the "Red widow" (Latrodectus bishopi) (Preston Malfham, 1998). The single species in Australia is commonly known as the Redback (Latrodectus hasselti). African species of this genus are also known as button spiders.
Silk of L. hesperus spiders is reputed to be particularly strong in comparison with the silk of other spiders. However, the results of a study by Blackledge et al. could not confirm this. The tensile strength (tensile strength) (or tensile strength), and other physical properties of Latrodectus Hesperus (Western Black Widow) silk were found to be comparable with the properties of silk orb-weavers, who had been tested in other studies.

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