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Deadliest Poisonous Spiders. A brief introduction. Content. Brown Recluse Spider Black widow funnel web spider Brazilian wandering spider Goliath bird-eater Spider. Black Widow Spider. its venom is reported to be 15 times stronger than a rattlesnake's. - PowerPoint PPT Presentation
Deadliest Poisonous Spiders
A brief introduction
• Brown Recluse Spider• Black widow• funnel web spider• Brazilian wandering spider• Goliath bird-eater Spider
Black Widow Spider
• its venom is reported to be 15 times stronger than a rattlesnake's.
• In humans, bites produce muscle aches, nausea, and a paralysis of the diaphragm that can make breathing difficult; bites can be fatal—usually to small children, the elderly, or the infirm.
• Fortunately, fatalities are fairly rare; the spiders are bite only in self-defense
• The animals most at risk from the black widow's bite are insects—and male black widow spiders. Females sometimes kill and eat their counterparts after mating in a macabre behaviour that gave the insect its name.
• Black widow spiders also use their webs to ensnare their prey.
• To feed, black widows puncture their insect prey with their fangs and administer digestive enzymes to the corpses.
Brown Recluse Spider
• Movement at virtually any speed is an evenly paced gait with legs extended, stopping naturally when renewing its internal hydraulic blood pressure.
• When threatened it usually flees, seemingly to avoid a conflict
• As indicated by its name, this species is rarely aggressive, and actual brown recluse bites are rare.
• Most bites are minor with no necrosis.
• However, a small number of bites produce severe dermonecrotic lesions, and, sometimes, severe systemic symptoms.
• Symptoms include organ damage, and occasionally even death; most fatalities are in pre-school children or those with a weaker-than-normal immune system.
Sydney funnel web spider
• Sydney funnel-webs are medium-to-large in size, with a body length ranging from 2 cm to 7 cm (0.9" to 3").
• The carapace covering the cephalothorax is almost hairless and so appears smooth and glossy.
• Males are smaller than females.
• The spider can be very aggressive when provoked. The long-lived female funnel-webs spend most of the time in their silk-lined tubular burrow retreats.
• Males, recognized by the modified terminal segment of the palp, tend to wander during the warmer months of the year looking for receptive females to mate with.
• Funnel-web spider venom contains a compound known as atraxotoxin which is highly toxic to primates.
• These spiders typically deliver a full envenomation when they bite, often striking repeatedly, due to their aggression and large chitinous cheliceral fangs.
• They are attracted to water and hence are often found in swimming pools, into which they often fall while wandering.
• The spiders can survive such immersion for up to twenty-four hours and can deliver bites when removed from the water.
Brazilian Wandering Spider
• The Brazilian wandering spiders are a genus of aggressive and highly venomous spiders found in tropical South and Central America.
• The Brazilian wandering spiders appear in Guinness World Records 2007 as the world's most venomous spider.
• …are so-called because they wander the jungle floor at night, rather than residing in a lair or maintaining a web.
• During the day they hide inside termite mounds, under fallen logs and rocks, and in banana plants and bromeliads.
• P. nigriventer is known to hide in dark and moist places in or near human dwellings.
• Its venom contains a potent neurotoxin, which acts as a broad-spectrum calcium channel blocker that inhibits glutamate release, calcium uptake and also glutamate uptake in neural synapses.
• At higher concentrations, this neurotoxin causes loss of muscle control and breathing problems, resulting in paralysis and eventual asphyxiation.
• In addition, the venom causes intense pain and inflammation following an attack.
Interesting facts• Aside from causing intense pain, the venom of the
spider can also cause priapism in humans. Erections resulting from the bite are uncomfortable, can last for many hours and can lead to impotence.
• The amount of P. nigriventer venom necessary to kill a 20 g mouse has been shown to be only 6 μg intravenously and 134 μg subcutaneously as compared to 110 μg and 200 μg respectively for Southern black widow.
Goliath bird-eater Spider
• The Goliath bird-eater Spider (also called the Goliath Birdeater) (Theraphosa blondi) is an arachnid belonging to the tarantula group.
• The Goliath birdeater’s venom is fairly harmless to humans.
• Generally bite humans only in self-defense.
• Despite its name, the Goliath Birdeater does not normally eat birds
• their diet consists primarily of insects and other invertebrates.
• However, because of its naturally large size, it is not uncommon for this species to kill and consume a variety of vertebrates.
The Champion Brazilian Wandering Spider
• Phoneutria includes some of the relatively few species of spiders known to present a threat to human beings.
• Danger to humans is rated as follows:• Toxicity• the capacity to deliver the venom• a sufficient quantity of venom• a disposition that makes a bite likely and proximity to human
• The spider's wandering nature is another reason it is considered so dangerous.
• In densely populated areas, Phoneutria species usually search for cover and dark places to hide during daytime, leading it to hide within houses, clothes, cars, boots, boxes and log piles, thus generating accidents when people disturb it.
The End is near!