The Top 5 Deadliest Spiders in the World

  Spider Location Toxin Group
1 The Brazilian wandering spider
(Phoneutria keyserlingi)
Central & South America Ctenitoxin
2 Sidney funnel-web spider
(Atrax robustus)
Australia Hexatoxin
3 Black widow spider
(Latrodectus mactans)
United States, Canada, Mexico, West Indies, South America Theriditoxin
4 Brown recluse spider, Violin spider
(Loxosceles reclusa)
United States Sicaritoxin
5 Redback Spider
(Latrodectus hasselti)
India, Indonesia, Phillipines, New Caledonia, Australia Theriditoxin
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 Facts
  1. According to the CPCS (California Poison Control System), there are at least 50,000 species of spider. Spiders are defined as having eight jointed legs, no wings, no antennae and only two body sections: the thorax and the abdomen. Spiders spend their entire life span capturing and eating about 2,000 insects a year. Even though spiders do a great deal of good for our environment, spiders are greatly feared by most of the population. Most spiders are killed only because they scare people, not because they are actually dangerous to humans. A spider generally bites a human because it was scared and bites to defend itself. Spiders generally prefer to live in undisturbed areas such as corners of the house or the eaves or in the garden where they can catch insects in peace.
  2. A black widow spider bite gives the appearance of a target, with a pale area surrounded by a red ring. Severe muscle pain and cramps may develop in the first two hours. Severe cramps are usually first felt in the back, shoulders, abdomen and thighs. Other symptoms include weakness, sweating, headache, anxiety, itching, nausea, vomiting, difficult breathing and increased blood pressure. According to the CPCS, no person in the United States has died from a black widow spider bite in over 10 years (since 2000). Black widow spiders generally live in trash, closets, attics, woodpiles, garages and other dark places. Young children, the elderly and those with high blood pressure are at highest risk of developing symptoms from a black widow spider bite.
  3. The brown recluse spider (Loxosceles reclusa) is named for its habit of hiding in dark corners, and is also known as the violin spider or fiddleback spider because of a violin-shaped marking. The brown recluse spider bite usually causes some pain or burning in the first 10 minutes, accompanied by itching. The wound takes on a bull's-eye appearance, with a center blister surrounded by an angry-looking red ring and then a blanched (white) ring. The blister breaks open, leaving an ulcer that scabs over. The ulcer can enlarge and involve underlying skin and muscle tissue. Pain may be severe. A generalized red, itchy rash usually appears in the first 24-48 hours. Other symptoms include fever, chills, nausea, vomiting, muscle aches and hemolytic anemia (a condition where the red blood cells are destroyed).
  4. According to the University of Sidney, the Sydney funnel web (and a few related Atrax species) is unquestionably the most dangerous spider in Australia. Of all the thousands of Australian spiders, arthropods and insects, only three have bites which alone are capable of causing death - the funnel-web spider (and related atrax species), the red back spider and the paralysis tick. The Sydney funnel web spider is a large (6-7 cm), black, aggressive, ugly looking spider with massive fangs. When disturbed it tends to rear up on its hind legs, a defensive posture that exposes the fangs. They don't jump. During a bite the spider firmly grips its victim and bites repeatedly; in most cases the experience is horrific. The venom is highly toxic. Before an effective anti-venom was developed, significant bites usually resulted in severe symptoms and death. The venom of the slightly smaller male spider is five times as toxic as the female. For some reason, human beings (and other primates and monkeys) are particularly sensitive to the venom, whereas toads, cats and rabbits are almost unaffected. The bite is usually immediately painful, and if substantial envenomation occurs, symptoms commence usually within a few minutes. They include, progressively: Piloerection, sweating, muscle twitching, salivation, lacrimation, tachycardia, and then severe hypertension. Then vomiting, airway obstruction, muscle spasms, writhing, grimacing, pulmonary oedema and extreme hypertension followed by unconsciousness, raised intracranial pressure, widely dilated pupils (often fixed), uncontrolled twitching, and death unless artificial ventilation is provided. After about 2 hours the muscle fasiculations and most symptoms start to subside, and are replaced with insidious but profound hypotension, primarily due to severe cardiac failure. There have been no reports of deaths however, when effective first aid had been instituted and, what is more, according to the Australian museum spider FAQ, the number of human deaths from authentic spider bites of any kind in Australia since 1979 has been zero (bees and wasps have caused far more deaths). A recent published medical study followed 750 genuine Australian spider bite cases with identified spiders over 27 months (1999-2001). Only 44 bites (6%, mostly redback spider bites) had significant effects. Only 6 redback bites and 1 Atrax bite were serious enough to need antivenom over this period.
  5. The venom of a Brazilian Wandering Spider is 30 times more powerful than that of a rattlesnake and they have the most active venom of any living spiders. Since 1926, 14 people are reported to have died from bites, however in 1996 an antidote was developed and no other deaths have officially been reported. Studies indicate only 33% of the spider bites actually contain any significant amount of venom. The Phoneutria fera and Phoneutria nigriventer (two species of Brazilian wandering spider) are the two most commonly implicated as the most vicious and deadly of the Phoneutria spiders. The Phoneutria not only has a potent neurotoxin, but is reported to have one of the most excruciatingly painful envenoms of all spiders due to its high concentration of serotonin. Brazilian wandering spiders have been found in bunches of bananas in importing countries far from Brazil. The Brazilian wandering spider venom can stimulate an erection for up to 2 hours. "The erection is a side effect that every man who gets stung by this spider will experience along with the pain and discomfort," said study team member Romulo Leite of the Medical College of Georgia. "We’re hoping eventually this will end up in the development of real drugs for the treatment of erectile dysfunction."
Top 5 facts sources: California Poison Control System (http://www.calpoison.org/public/spiders.html), The University of Sidney (http://www.anaes.med.usyd.edu.au/venom/spiders.html), Myths about "Dangerous" Spiders; Burke Museum of Natural History & Culture. Various.
Tags: Animals & Nature, Deadliest

Sources:  Top 5 of Anything Research 2016.

List Notes: Please note: it is difficult to define exactly which spider in the world is the most dangerous to humans, therefore the list includes only spiders that have been known to cause human deaths. Exact figures for deaths or venom load for each spider is difficult or impossible to determine and thus this list should be considered as a rough ranking rather than an exact list of deadly spiders.
Deadliest Spiders in the World

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