Here we take a look at the fiven most dangerous spiders on earth.
Number 5: Red-back spider (Latrodectus hasselti)
The redback spider (Latrodectus hasseltii) is a dangerous spider endemic to Australia. It is a close cousin of pretty known black widow, which is found throughout the world. The female is easily recognisable by her black body with a prominent red stripe on the back of her abdomen. Females have a body length of about a centimetre, while the male is smaller, being only 3 to 4 mm long. The redback spider is one of few arachnids which usually display sexual cannibalism while mating.
Redbacks are considered one of the most dangerous species of spiders in Australia. Its neurotoxic venom is toxic to humans, with bites causing severe pain, often for over 24 hours. An antivenom is commercially available, and since its introduction in 1956, no deaths due to redback bites have been reported.+
Redback spider bites rarely cause significant morbidity, and deaths are even more rare. Throughout Australian history, only 14 deaths from redbacks have been recorded. Hundreds or even thousands of people are thought to be bitten each year across Australia, although only about 20% of bite victims require treatment. Children, the elderly, or those with serious medical conditions are at much higher risk of severe side effects and death resulting from a bite. The larger female spider is responsible for almost all cases of redback spider bites in humans.
Most bites occur in the warmer months between December and April, in the afternoon or evening. As the female redback is slow-moving, and rarely leaves its web, bites generally occur as a result of a person placing a hand or other body part too close to the web, such as when reaching into dark holes or wall cavities. Bites can also occur if a spider has hidden in clothes or shoes.
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Number 4: Sydney funnel-web spider (Atrax robustus)
The Sydney funnel-web spider (Atrax robustus) is a species of Australian funnel-web spider usually found within a 100 km (62 mi) radius of Sydney, New South Wales, Australia. It is a venomous spider with a bite capable of causing serious injury or death in humans if left untreated.
Funnel-web spider venom contains a compound known as atracotoxin, an ion channel inhibitor, which makes the venom highly toxic for humans and primates. However, it does not affect the nervous system of other mammals. These spiders typically deliver a full envenomation when they bite, often striking repeatedly, due to their defensiveness and large chitinous cheliceral fangs. There has been no reported case of severe envenoming by female funnel-web spiders, which is consistent with the finding that the venom of female specimen is less potent than the venom of their male counterparts. In the case of severe envenoming, the time to onset of symptoms is less than one hour; with a study about funnel-web spider bites finding a median time of 28 minutes. There is at least one recorded case of a small child dying within 15 minutes of a bite from a Sydney funnel-web spider.
Since the antivenom became available in 1981, there have been no recorded fatalities from Sydney funnel-web spider bites. In September 2012, it was reported that stocks of antivenom were running low, and members of the public were asked to catch the spiders so that they could be milked for their venom. One dose of antivenom requires around 70 milkings from a spider.
When threatened or provoked, funnel-web spiders will display aggressive behaviour, rearing up on its behind legs and displaying their fangs. When biting, the funnel-web spiders maintain a tight grip on their victim, often biting repeatedly.
Number 3: Brazilian wandering spider (Phoneutria fera)
Brazilian wandering spiders, armed spider or banana spiders, are a genus of defensive and venomous spiders of potential medical significance to humans. They are mainly found in tropical South America, with one species in Central America.
The Brazilian wandering spiders appear in Guinness World Records from 2010 as the world’s most venomous spider. However, several venomous species of arachnid are far more likely to attack a human, and the Guinness book of World Records states that although the Brazilian wandering spider is the most toxic, more deaths actually occur from black widow and brown recluse spider bites, due to the rarity of the Wandering spider biting anyone.
Wandering spiders 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.
Brazilian wandering spiders are widely considered the most venomous species of spider. At deadly concentrations, their venom causes loss of muscle control and breathing problems, resulting in paralysis and eventual asphyxiation. In addition, the venom causes intense pain and inflammation following a bite. Aside from causing intense pain, the venom of the spider can also cause erection which can last for many hours and can lead to impotence.
The spider’s wandering nature is another reason it is considered so dangerous. In densely populated areas, it 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. Its other common name, “banana spider”, comes from its tendency to hide in banana bunches or plantations, and it is occasionally found as a stowaway within shipments of bananas. These spiders can also appear in banana crates sent to grocery stores and bulk food centers around the world.
Number 2: Brown recluse spider (Loxosceles reclusa)
Brown recluse spiders are usually between 6–20 mm (1⁄4 in and 3⁄4 in), but may grow larger. While typically light to medium brown, they range in color from cream-colored to dark brown or blackish gray. Most spiders have eight eyes; recluse spiders have six eyes arranged in pairs (dyads) with one median pair and two lateral pairs. Only a few other spiders have three pairs of eyes arranged in this way. It is native to the United States from the southern Midwest south to the Gulf of Mexico.
The brown recluse spider is rarely aggressive, and bites from the species are uncommon. In 2001, more than 2,000 brown recluse spiders were removed from a heavily infested home in Kansas, yet the four residents who had lived there for years were never harmed by the spiders, despite many encounters with them. The spider usually bites only when pressed against the skin, such as when tangled within clothes, towels, bedding, inside work gloves, etc. Many human victims report having been bitten after putting on clothes that had not been worn recently, or had been left for many days undisturbed on the floor. However, the fangs of the brown recluse are so tiny they are unable to penetrate most fabric.
The bite frequently is not felt initially and may not be immediately painful, but it can be serious. The brown recluse bears a potentially deadly hemotoxic venom. The venom spreads throughout the body in minutes. The systemic symptoms most commonly experienced include nausea, vomiting, fever, rashes, and muscle and joint pain. Rarely, such bites can result in hemolysis,thrombocytopenia, disseminated intravascular coagulation, organ damage, and even death. Sometimes the bite forms a necrotizing ulcer that destroys soft tissue and may take months to heal, leaving deep scars. These bites usually become painful and itchy within 2 to 8 hours. Pain and other local effects worsen 12 to 36 hours after the bite, and the necrosis develops over the next few days. Over time, the wound may grow to as large as 25 cm (10 inches). The damaged tissue becomes gangrenous and eventually sloughs away.
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Number 1: Black Widow (Latrodectus mactans)
Latrodectus mactans, or Southern black widow or simply black widow, is a highly venomous species of spider. They are well known for the distinctive black and red coloring of the female of the species and for the fact that she will occasionally eat her mate after reproduction (hence the name – Black widow). The species is native to North America. The venom might be fatal to humans.
Although these spiders are not especially large, their venom is extremely potent. They are capable to inject the venom to a point where it can be harmful. The males, being much smaller, inject far less venom. The actual amount injected, even by a mature female, is very small in physical volume. When this small amount of venom is diffused throughout the body of a healthy, mature human, it usually does not amount to a fatal dose (though it can produce the very unpleasant symptoms of latrodectism). Sixty-three deaths were reported in the United States between 1950 and 1959. On the other hand, the geographical range of the widow spiders is very great. As a result, far more people are exposed, worldwide, to widow bites than to bites of more dangerous spiders, so the highest number of deaths worldwide are caused by members of this genus. Widow spiders have more potent venom than most spiders, and prior to the development of antivenom, 5% of reported bites resulted in fatalities. The venom can cause a swelling up to 15 cm. Improvements in plumbing have greatly reduced the incidence of bites and fatalities in areas where outdoor privies have been replaced by flush toilets.