Selasa, 26 April 2011

Some of the World’s Most Venomous and Dangerous Spiders

Some of the World’s Most Venomous and Dangerous Spiders

Brazilian Wandering Spider (aka Phoneutria Nigriventer)

The Brazilian wandering spider (aka Phoneutria nigriventer) is considered to be one of the most dangerous spiders in the world. It lives in South America, doesn’t create a web, and never stays in one place. That’s where it gets its name from –  Phoneutria sp. It’s just 10 centimeters in length but can kill about 225 mice with its poison. It can hardly kill a wise man, but can indeed cause a major allergic reaction. Fortunately there was an antidote found for its poison. The Phoneutria spider mostly feeds on insects, smaller spiders, and sometimes birds or even lizards which are much bigger in size. It prefers to hide in fruit baskets, especially among bananas, and that’s why it earned the nickname of the “banana spider.” An interesting fact from states that the venom of phoneutria can stimulate a long-time uncomfortable erection.

The Brown Recluse Spider

The brown recluse spider, or violin spider (Loxosceles recluse), is one of the few spiders in the world known to be harmful for humans. It inhabits midwestern and southeastern states of the US, especially California. It is recognized by its brown body and violin pattern on the back. The spider is rather small – from 0.6 to 2 centimeters – which makes it not exactly simple to identify. It seeks out warm, dry and dark places like attics, closets, or old tires. Unlike most spiders with 8 eyes, the brown recluse has 6 eyes in 3 pairs arranged in a semi-circle in front of the violin markings. When the brown recluse bites, there are often no evident symptoms occuring during the first 24 hours. In the meantime, poison spreads all throughout the human’s body. That’s why it’s important to hospitalize a patient as soon as possible. Brown recluse spiders are not aggressive and bite only when threatened.

The Black Widow Spider (Latradectus Lugubris)

This spider is known to be very harmful to humans because of its venom which exceeds the poison of rattlesnake by a multiple of 15. Black widows inhabit prairie and desert places all over the world. Females are around 2 cm in length and are more dangerous than males. The female invariably kills the male after mating, which is in fact how the black widow got its name. Black widows are usually recognized by a black body with some red dots on it. The spider is usually active from April to November with its peak period of aggression in June-July. It should be noted that black widows, much like the other venomous spiders, attack iprey only when disturbed. Its bite brings severe stomach, chest, and waste pains with convulsions and a red rash. It’s very important to deactivate the poison during the first 30 seconds after the bite by burning a match directly on the bite spot.
Tarantula (Theraphosidae)

Tarantulas represent a group of hairy and very large (approximately 3-4 cm in length) spiders which belong to the family Theraphosidae. There are many color variations of tarantulas – from light-brown to dark-gray. Tarantulas live in deep and damp holes in prairies and desert places. In the dark of night tarantulas hunt their prey. The tarantula’s poison is not very dangerous to humans, and some people even keep them as pets. The worst of a tarantula bite to a human is generally severe pain in the spot of the bite, later changing into reddening and swelling. Within 5-6 hours the mild illness resulting from the bite passes.

Water Spider (Argyroneta Aquatica, Latin for “Silvery Net”)

Water spiders or diving bell spiders (Argyroneta aquatica) inhabit fresh ponds in Northern and Central Europe and Northern Asia. Argyroneta is one of a type of air-breathing water spiders who spend their whole life under water. It’s good at diving, with speeds of 2.3-3.5 cm per second with its length of 1.5-1.7 cm. The water spider weaves its web among water plants and stocks it with air from the surface, which looks like a diving bell. Argyroneta is not considered harmful to humans. It mostly hunts small crayfish and insect larvae, which it kills with its poison. Water spiders surround their living place with safety nets. These nets also signal them about prey’s arrival. The bite of the spider is very annoying to humans even if not dangerous.

Australian Funnel-Web Spider (Family Hexathelidae)

Australian funnel-web spiders live on the eastern coast of Australia in damp and cool places. Funnel-web spiders are known as one of three of the most dangerous spiders in the world. As far as being dangerously venomous goes, the funnel-web competes with its relatives, the Australian H. Formidabilis and Brazilian Phoneutria fera (also known as the Brazilian wandering spider). Funnel-web spiders have a dark color which varies from brown to black with a glossy covering. The fangs are so strong that they can bite through even a shoe. The venom of a funnel-web spider can kill a human within an hour. Fortunately, there is antidote for its poison. Specimens of funnel-web spiders are found in New South Wales, Victoria, South Australia, and Queensland which is how they got their name. Each of these are presented on the pictures below: Sydney funnel-web (Atrax Robustus), Victorian funnel-web spider (Hadronyche modesta) and Blue Mountains funnel web spider (Hadronyche versuta).

Crab Spider (Selenopidae)

The Selenopidae family includes more than 3,000 crab spider species. They got their name from Selene, the Greek goddess of the moon. Crab spiders resemble crabs with their front pair of legs angled alongside their flattened bodies. Also, just like crabs they can move sideways and backwards. Usually crab spiders are found in northern America and sometimes in southern Europe and Asia. They do not weave webs; they usually hunt on the ground while hiding among vegetation such as flowers. Crab spiders are not known to be venomous to humans, and are sometimes mistaken for an unrelated genus, Sicarius, which are close relatives to the brown recluse and which are indeed very dangerous to humans.

Yellow Sac Spiders (Cheiracanthium Punctorium)

The yellow (golden) sac spiders inhabit mostly European countries. These spiders are rather small (10 mm in length), are yellowish in color, and are hardly recognized. Yellow spiders build sac-like tubes under things like stones to serve as their home. Sometimes they are found inside houses. Their bites are known  to be at least clinically dangerous and often are misdiagnosed as bites of the brown recluse spider. The bite of a yellow sac spider causes severe pain with the development of a necrotic wound (although not as intense as that from a brown recluse). Just like other spiders they are prone to bite defensively.

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