Of the 35,000 species of spiders described worldwide (out of an estimated 170,000 species), only a handful are considered to be dangerous and only 27 are known to have caused human fatalities. Though most people have a big fear of spiders, it seems that venomous spiders are not such a big threat to humans as many people believe. First of all, studies have shown that most serious bites attributed to spiders were, in fact, due to other causes, notably other arthropods. There are, however, a few exceptions, and bites from certain species can cause severe dermatological lesions and other symptoms which require urgent medical treatment and care. The spiders of medical importance in Asia include widows and cupboard spiders (also called Brown House spiders or False Widows, family Theridiidae) which venom may contain neurotoxins responsible for serious systemic envenomation. 1. Widows (Latrodectus) The name widow originates from the idea that the male is eaten after mating but this is uncommon in the field. The genus Latrodectus contains around thirty described species and belongs to the large family Theridiidae. Black and Brown Widows occur on all continents, except Antarctica and are mostly common in tropical and sub-tropical regions. The female spider is 12-16 mm long while males are 4 to 5 times smaller. Widows are active during the day and rarely come indoors. The female spins a messy three-dimensional web in protected corners of fields, gardens, near stones and woodpiles and in vegetation, in which she hangs upside down. The male spider does not produce a web and is not considered dangerous for humans. Bites of the females of Latrodectus are often initially painful but are also sometimes not felt. In 50% of hospitalized cases, a severe pain lasts from one to three days. The use of antiserum may shorten the duration of the symptoms but is usually not required. Analgesics, myorelaxants and calcium gluconate are used to relief the symptoms. The fear for this spider, often considered deadly is, however, exaggerated. Indeed, since 1954 it hasn't been responsible for any fatal bite cases in Australia, nor since 1983 in the USA, and there has never been a reported death by these spiders in the rest of the world. Besides, Widows are not aggressive spiders. - Latrodectus dahli: found from the Middle East to central Asia.  A Brown widow spider very common in Thailand, where it likes to settle inside garages and other human structures. It is shy and not very likely to bite, however it has a strong neurotoxic venom and can be dangerous, especially for young children. - Latrodectus erythromelas: found in Sri Lanka. 2. Sac Spiders (Cheiracanthium) Family Miturgidae (previously Clubionidae) - Yellow Sac Spider (Cheiracanthium punctorium)  It can measure up to 15 mm and, like other members of the Miturgidae family, it has a long first pair of legs and stout fang. Those fangs can penetrate the human skin causing a sharp pain that commonly last for twelve hours, and in some cases for as long as ten days. Females build an egg sac of about 4 cm in high grass. It opens below and is aggressively defended. - Cheiracanthium japonicum: found in Japan. 3. Tarantulas Contrary to popular belief, tarantulas are venomous, like most spiders. No one has ever died from a bite of a tarantula though. The potency of the venom depends on the kind of tarantula. Tarantulas from the new world (Americas) have the no worse than bee sting venom. Instead though, they can kick hair off their legs and abdomen which can cause bad rashes. Old world tarantulas (Asia, Middle East, Africa) are usually more aggressive, have a much stronger venom, and may require medical attention (especially for the Poecilotheria and Haplopelma genus). 3.1 Poecilotheria Poecilotheria is a genus of the family Theraphosidae containing various species of arboreal tarantula. Poecilotheria spiders are native to Sri Lanka and India. In the wild, most arboreal tarantulas live in holes of tall trees where they make asymmetric funnel webs. They prey mostly on various flying insects, which they catch manually (not in a web) and paralyze. Poecilotheria spiders sometimes live communally, especially when the availability of tree holes is limited. Poecilotheria are very fast and may attack when cornered, although they generally prefer flight to fight. Although there has never been a recorded death from any tarantula bite, Poecilotheria species have a more potent venom than most other tarantulas and their bite, which causes an intense pain is considered to be medically significant. Poecilotheria species are: - Gooty Sapphire Ornamental Tree Spider, Gooty Sapphire. Found in the southeastern part on India and in Sri Lanka. The name "Gooty" comes from the town where this species was first discovered. This metallic blue tarantula likes hot humid environments. Its leg span measures between 15 and 20 cm (6- 8 inches). Females can live for about 12 years, males only for 3 or 4. The Gooty Sapphirre is a favorite with tarantula enthusiasts and adult specimens can price above $500 in the USA. - Poecilotheria fasciata: found in Sri Lanka 3.2 Haplopelma This genus of old-world tarantulas are found in the rain forests of southeast Asia: Myanmar, southeastern China, Cambodia, Thailand, Vietnam, Malaysia, Singapore, and Borneo. They need humidity levels of up 70% or more. These large spiders typically have leg spans ranging from 13 to 20 cm (4.5 to 8 inches). Like all old-world tarantulas, the Haploplema spiders lack the urticating hairs of their new world counterparts, and use biting as a primary means of defense. They are reputed to have a bad temper and are likely to bite when handled. Old world tarantulas are known for having strong venom (but the venom of many species still has to be studied) Species in Haplopelma include: - Chinese Bird Spider, Black Earth Tiger (Haplopelma hainanum, Haplopelma schmidti) This species of tarantula is native to many parts of Asia, notably the tropical rain forests of China and Vietnam. This jet black spider is huge: its leg span can reach up to 20 cm (8 inches). Although the Chinese Bird normally preys on insects and small rodents, this fearsome and extremely aggressive species will not hesitate to bite a human being, often attacking without provocation. This aggressive nature, backed by an incredible speed and very large fangs, have led to this species being considered one of the most dangerous spiders in the world. A small dose of the Chinese Bird's venom, which attacks the nervous system, and is fatal to laboratory rats and mice. - Thailand Black Tarantula, Bird Eating Spider (Haplopelma minax)  - Cobalt Blue Tarantula (Haplopelma lividum) Found in Myanmar and Thailand. - Thai Zebra Tarantula (Haplopelma albostriatum), also known as the "edible spider": found in Myanmar, Thailand, Cambodia. Sources: http://www.entomon.net/venomous-most-deadly-spiders-kevlar-webs.htm http://venomous-spiders.nanders.dk/ http://spiders.ucr.edu/dermatol.html http://en.wikipedia.org/wiki/Latrodectus http://www.entomon.net/framed-black-insect-spider-from-asia.htm http://my.funtrivia.com/submitquiz.cfm?quiz=261121 http://www.thaivisa.com/forum/Spiders-Thailand-t69841.html http://answers.yahoo.com/question/index?qid=20080720170839AAGTL3S http://www.ncbi.nlm.nih.gov/pubmed/12165044 http://en.wikipedia.org/wiki/Poecilotheria_metallica http://en.wikipedia.org/wiki/Poecilotheria_regalis http://en.wikipedia.org/wiki/Poecilotheria http://en.wikipedia.org/wiki/Ornithoctoninae http://en.wikipedia.org/wiki/Haplopelma http://en.wikipedia.org/wiki/Cobalt_blue_tarantula http://en.wikipedia.org/wiki/Cheiracanthium_punctorium |
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