Reddish Vale Country Park
Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every habitat with the exception of air and sea colonization. As of 2008, approximately 40,000 spider species, and 109 families have been recorded by taxonomists worldwide.
Anatomically, spiders differ from other arthropods, in that the usual body segments are fused into two tagmata, the cephalothorax and abdomen, and joined by a small, cylindrical pedicel. Unlike insects, spiders do not have antennae. Unlike most arthropods, spiders have no extensor muscles in their limbs and instead extend them by hydraulic pressure.
Male spiders identify themselves by a variety of complex courtship rituals to avoid being eaten by the females. Males of most species survive a few matings, limited mainly by their short life spans. Females weave silk egg-cases, each of which may contain hundreds of eggs. Females of many species care for their young, for example by carrying them around or by sharing food with them. A minority of species are social, building communal webs that may house anywhere from a few to 50,000 individuals. Social behavior ranges from precarious toleration, as in the aggressive widow spiders, to co-operative hunting and food-sharing. Although most spiders only live for at most two years, tarantulas and other mygalomorph spiders can live up to 25 years in captivity.
About a dozen or so spiders native to Great Britain can cause quite a nasty bite: the tube web spider, the false widow, woodlouse spider, walnut orb weaver, cellar spider, black lace weaver, mouse spider, rustic wolf spider, bark sac spider, stone spider, cross (or garden) spider, Bruennichi's Argiope, and the money spider.
Well over 90% of patients seeking treatment for bites in the UK were bitten by one of the first 12 of those species, with there actually being over 700 native species. Most are harmless, and venomous bites in the UK are usually bites from non-native spiders, or are in fact insect bites wrongly blamed on spiders. None of the native spiders are particularly venomous.
Even the world's most venomous spiders rarely result in a human death.
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Nursery Web Spiders
Cucumber Green Spider
Walnut Orb Spider
Spiders are air-breathing arthropods that have eight legs, and have mouths with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms.