Top 10 most dangerous viruses in the world, Science, In-depth reporting on science and technology, DW

Top 10 most dangerous viruses in the world

Bird flu, Ebola and Zika — there seems to be news on a new dangerous virus almost every day. But so far, experts are saying that Zika itself isn’t as bad as HIV, Ebola and these other eight viruses.

1. The most dangerous virus is the Marburg virus. It is named after a small and idyllic town on the river Lahn — but that has nothing to do with the disease itself. The Marburg virus is a hemorrhagic fever virus. As with Ebola, the Marburg virus causes convulsions and bleeding of mucous membranes, skin and organs. It has a fatality rate of 90 percent.

2. There are five strains of the Ebola virus, each named after countries and regions in Africa: Zaire, Sudan, Tai Forest, Bundibugyo and Reston. The Zaire Ebola virus is the deadliest, with a mortality rate of 90 percent. It is the strain currently spreading through Guinea, Sierra Leone and Liberia, and beyond. Scientists say flying foxes probably brought the Zaire Ebola virus into cities.

3. The Hantavirus describes several types of viruses. It is named after a river where American soldiers were first thought to have been infected with the Hantavirus, during the Korean War in 1950. Symptoms include lung disease, fever and kidney failure.

4. The various strains of bird flu regularly cause panic — which is perhaps justified because the mortality rate is 70 percent. But in fact the risk of contracting the H5N1 strain — one of the best known — is quite low. You can only be infected through direct contact with poultry. It is said this explains why most cases appear in Asia, where people often live close to chickens.

5. A nurse in Nigeria was the first person to be infected with the Lassa virus. The virus is transmitted by rodents. Cases can be endemic — which means the virus occurs in a specific region, such as in western Africa, and can reoccur there at any time. Scientists assume that 15 percent of rodents in western Africa carry the virus.

The Marburg virus under a microscope

6. The Junin virus is associated with Argentine hemorrhagic fever. People infected with the virus suffer from tissue inflammation, sepsis and skin bleeding. The problem is that the symptoms can appear to be so common that the disease is rarely detected or identified in the first instance.

7. The Crimea-Congo fever virus is transmitted by ticks. It is similar to the Ebola and Marburg viruses in the way it progresses. During the first days of infection, sufferers present with pin-sized bleedings in the face, mouth and the pharynx.

8. The Machupo virus is associated with Bolivian hemorrhagic fever, also known as black typhus. The infection causes high fever, accompanied by heavy bleedings. It progresses similar to the Junin virus. The virus can be transmitted from human to human, and rodents often the carry it.

9. Scientists discovered the Kyasanur Forest Virus (KFD) virus in woodlands on the southwestern coast of India in 1955. It is transmitted by ticks, but scientists say it is difficult to determine any carriers. It is assumed that rats, birds and boars could be hosts. People infected with the virus suffer from high fever, strong headaches and muscle pain which can cause bleedings.

10. Dengue fever is a constant threat. If you’re planning a holiday in the tropics, get informed about dengue. Transmitted by mosquitoes, dengue affects between 50 and 100 million people a year in popular holiday destinations such as Thailand and India. But it’s more of a problem for the 2 billion people who live in areas that are threatened by dengue fever.

12 ways to prevent cancer

Destiny is in your hands

Being diagnosed with cancer is a shock that hits you hard. And yet almost half of all cancer cases could be prevented. Smoking alone triggers about every fifth tumor. The toxic cigarette smoke does not only cause lung cancer but many other kinds of tumors as well. Smoking is the most frequent self-imposed cause for cancer, but not the only one.

12 ways to prevent cancer

Being overweight increases cancer risk

In second place of cancer-causing agents: obesity. Why it causes cancer? Enhanced insulin levels increase the risk of almost all sorts of cancer, especially when it comes to kidney, gall bladder, and oesophagus cancer. Overweight women produce increasing amounts of female sex hormones in their fat tissue and hence have a higher risk for uterine or breast cancer.

12 ways to prevent cancer

Don’t be a couch potato!

People who don’t move enough are especially likely to get cancer. Long-term studies show that exercising prevents tumors. After all, working out lowers the insulin levels while preventing you from gaining weight. And it doesn’t have to be high-performance sport. Even just going for a walk or a bike ride makes a big difference.

12 ways to prevent cancer

Don’t drink too much!

Alcohol promotes tumors in the oral cavity, the throat and the oesophagus. The combination of smoking and drinking is especially dangerous and increases the risk of cancer up to a hundredfold. While dinking one glass of wine a day is healthy and supports the cardiovascular system, you shouldn’t drink more than that.

12 ways to prevent cancer

Don’t eat too much red meat!

Red meat can cause intestinal cancer. The exact cause has not yet been determined, but long-term studies show a significant correlation between the consumption of red meat and intestinal cancer. Beef is especially dangerous, but even pork can cause cancer to a minor degree. Meat consumption increases the risk of cancer one and a half times. Fish, however, prevents cancer.

12 ways to prevent cancer

No more BBQ?

When barbecuing meat, carcinogenic substances are released, such as polycyclical aromatic hydrocarbons. It has been proven in animal experiments that these chemical compounds can cause tumors. However, long-term studies with humans have not yet unambiguously proven the same. It’s possible that consuming the meat causes cancer, not the way it is prepared.

12 ways to prevent cancer

Avoid fast food

A good diet consisting of vegetables, fruits and dietary fibers can prevent cancer. However, when conducting long-term studies researchers found that a healthy diet has less impact on cancer prevention than previously assumed. It only decreases the risk of getting cancer by a maximum of 10 percent.

12 ways to prevent cancer

Too much sun is harmful

The sun’s UV radiation can penetrate genomes and change them. While sunscreen protects the skin from sunburn, the skin absorbs too much radiation as soon as it starts getting tanned.

12 ways to prevent cancer

Cancer triggered by modern medicine

X-rays harm genomes. With an ordinary radiogram the exposure is only minor. But it’s a different story for computed tomography, which you should only undergo when necessary. Magnetic resonance imaging is harmless. But did you know that you’re even exposed to cancer-causing radiation when you’re on an airplane?

12 ways to prevent cancer

Cancer triggered by infection

Human papillomaviruses can cause cervical cancer. Hepatitis B and C can cause hepatocytes to degenerate. The bacterium helicobacter pylori (pictured above) settles in your stomach and can cause stomach cancer. But not all hope is lost. You can get vaccinated against many of these pathogens and antibiotics help fight helicobacter pylori.

12 ways to prevent cancer

Better than its reputation

The oral contraceptive pill slightly increases the risk of getting breast cancer, but at the same time it strongly decreases the risk of getting ovarian cancer. All in all the pill is more protective than harmful, at least when it comes to cancer.

12 ways to prevent cancer

A true stroke of fate

But even if you do everything right, you’re never completely immune from getting cancer. Half of all cancer cases are caused by the wrong genes or simply age. Brain cancer is particularly likely to be inherited.

m.dw.com

The Deadliest Animals in America, Ranked

A very scary and poisonous western diamondback rattlesnake. (Photo: Getty)

Of all the animals in America, most are cute, fluffy, and simply amazing… whereas others are absolutely terrifying and will totally attack you for no reason.

Tiny little bunny rabbits? Adorable, and will never, ever hurt you. But a rattlesnake? Super venomous, and will totally stare at you with its beady little snake eyes, and then proceed to attack you with the full intention of taking you down.

In a new study from Stanford University, researchers analyzed data from 2008 to 2015 of mortality rates associated with venomous and nonvenomous animals in the U.S., and the results were definitely not what you’d expect.

Not that you’d find penguins in the wild in North America.

But before we get to the list of deadliest animals, here are some stats on animal-related deaths in America: An average of only 1,610 people die from animals every year, which comes out to 4.8 people per 10 million. When you think about it, that’s a minuscule fraction of the total 2.7 million deaths per year, meaning your odds of meeting your maker at the hands of an animal are pretty slim.

Even so, you’d think those few deaths happened because someone accidentally sat on a Black Widow spider and got bit on the asscheek, or was unlucky enough to fall into a Louisiana swamp and become alligator chow, right? Right. But no. That’s not at all how most animal-related deaths happen, which is all the more reason to be slightly worried.

Death by spider.

Without further ado, the six deadliest (types of) animals in the United States, ordered from least lethal to most.

6. Crocodiles, scorpions, rats, centipedes, and millipedes

Contrary to popular belief, this totally unrelated bunch of animals are only responsible for a fraction of a percent of deaths, so they hardly count as super deadly. But still, be careful.

5. Venomous spiders

Next, making up three percent of casualties are venomous spiders, which includes Recluse spiders, Widows, and other unsettling and highly poisonous creepy-crawlies.

Not sure why this person thinks it’s a good idea to hold a Black Widow spider.

4. Venomous snakes and lizards

Another three percent of fatalities are from poisonous snakes and lizards, so if I were you, I wouldn’t go poking around under rocks and shit in case a serpent pops out and sinks its fangs into your arm.

3. Dogs

This one personally makes me very sad. These beautiful creatures are responsible for 17 percent of U.S. animal-related deaths.

Not this dog. This is a good boy.

I should mention, though, that most (if not all) of dog-related deaths are from pit bull attacks. Just so you know.

This pit bull might kill you, though. (Photo: Getty)

2. Hornets, wasps, and bees

This one is not too surprising, is it? Hornets, wasps, and bees are responsible for 30 percent of animal-related deaths, and I’m going to go ahead and assume the majority of this percentage are people who are deathly allergic to stinging insects and die of anaphylaxis, and a small number of idiots dumb enough to fuck around with their nests, get stung a bunch of times, and die of toxicity.

Disclaimer: This man is very much still alive.

1. Farm animals

That’s right. The number one deadliest animal in the continental United States is the average farm animal — namely cows and horses.

According to the researchers, the number one deadliest category of animal is “other mammals,” which encompasses mainly farm animals like cattle and horses, and the occasional raccoon and such. These account for 36 percent of deaths, which means Old MacDonald’s crew is not screwing around. They will mess you up.

“From this search, we found that the rates of death from encounters with animals has remained relatively stable from the last time we performed this analysis,” says lead researcher Dr. Jared Forrester.

“Animal-related deaths in ‘controllable’ situations, such as on the farm or in the home, still account for the majority of the deaths. Increased specificity in the coding of deaths due to animals in farm environments would help public health professionals target interventions.”

www.maxim.com

The 12 Most Dangerous Critters in Texas

These creatures—some creepy crawlers, some fearsome beasts, some microscopic threats—can and will kill you, maybe.

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Illustration by Bolora Munkhbold; Alligator: apple2499/Getty, WikiCommons

Forget heart disease and cancer and all the other tragic or banal ways most of us will exit this world of the living. Instead, seek distraction via our completely unscientific and by no means definitive list of the most dangerous creatures in Texas that could, by some fluke, kill you first.

Brain-eating Amoebas

For sweet relief from the interminable hellscape that is the Texas summer, plunk your hot bod into the nearest swimming hole. Just beware of the Naegleria fowleri, a nasty little single-celled organism lurking in warm water and nicknamed for its favorite pastime—literally eating human brains. Naegleria enters your body through the nose and shimmies into your skull, where it plays around in your brains, destroying the tissue. (This amoeba can also strike when you use contaminated tap water to flush your sinuses, FYI.) It is present in freshwater throughout Texas, and there’s really no body of water that can be considered safer from it than others. Experts advise keeping your head dry when wading in a stream or lake where water temperatures are warm and water levels are low.

The good news? Infections are rare: only 34 were reported in the United States between 2009 and 2018, the CDC reports. “It is extremely serious and almost always fatal,” Texas Department of State Health Services spokesman Chris Van Deusen told KWTX in September. “Since it’s so rare, we don’t know why a few people get sick while millions who swim in natural bodies of water don’t.”

Flesh-eating Bacteria

Heading to the beach? Just hope you don’t encounter a particularly vicious bacterium called vibrio, which attacks swimmers in the ocean or brackish water. Vibrio gets under your skin through cuts, scrapes, or even insect bites, then spreads quickly through the soft tissue of your body—a disease called necrotizing fasciitis, which causes painful red swelling followed by fever, ulcers, blisters, black spots under the skin, and oozing pus. You also might start to feel dizzy, fatigued, or nauseated, or you could have diarrhea.

According to Texas A&M College of Medicine professor Hector Chapa, between 700 and 1,200 people contract necrotizing fasciitis every year. One in three of those people will die, as did two men at Texas beaches in July. If flesh-eating bacteria finds its way into your body, you need antibiotics as quickly as possible, followed by possible surgery and the removal of dead tissue to keep the infection from spreading, before sepsis, shock, and organ failure set in.

Snakes

They slither throughout the state, but for a generation of TV-watching Texas children, the Lonesome Dove miniseries instilled a healthy fear of one snake in particular: “Water moccasins!” unlucky young sprout Sean O’Brien screamed moments before the credits rolled on the first episode, as he thrashed in the Nueces River in a terrifying tangle of moccasins, also known as cottonmouths—right before one bit him on his cheek and sent him to an early grave.

Elsewhere, Texans looking out for coral snakes remind themselves that “red and yeller kill a feller.” They also watch out for the copperhead and the western diamondback rattlesnake, named for its distinctive diamond-patterned markings. But compared with many other snakes, the timber rattlesnake, also known as the canebrake rattler, is doubly deadly. It possesses not one but two kinds of venom: neurotoxic, which attacks the nervous system, paralyzing its victim; and hemotoxic, which destroys body tissue, making you easy to digest. I knew an East Texan who nearly died when a canebrake fanged his hand, permanently gnarling a couple of his fingers.

Spiders

First, the good news: the male black widow spider is harmless to humans. The bad news: the female black widow, which eats the male after mating with him, will seriously mess you up.

The female is jet black, with a red or yellow hourglass shape on its underside. Its victim might not even notice the pinprick of its bite, only feel an array of unpleasant symptoms later, from cramping and convulsions to sweating, tremors, vomiting, and loss of consciousness. Look for black widows around woodpiles and “outdoor toilets,” warns the Texas Department of State Health Services.

Texas’s other species of venomous spider, the brown recluse, often hides in dark basements or garages. It’s golden brown, with a dark fiddle-shaped pattern on its back, and its venom can cause fever and chills, lesions, restlessness, or—believe it or not—“nothing.”

Alligators

At night, when alligators mosey into the waters of Texas bayous and swamps, pairs of their eyes catch the moonlight and seem to glow. With their sharp teeth and powerful jaws, and bodies weighing close to a thousand pounds, they can drag you underwater to drown you. If a gator hisses, you know you’re too close. These primordial reptiles rarely hassle people, unless they lose their fear of humans and become aggressive. Four years ago in Orange, a 28-year-old man became the first fatality from an alligator attack in Texas since 1836 when he uttered a few poorly chosen last words (which quickly swept the internet and became an unfortunate catch phrase) and jumped for a late-night swim into a bayou where a twelve-foot-long alligator lurked.

Sharks

The Shark Attack Database reports 58 unprovoked shark attacks in Texas since 1900, including five that were fatal. The last person killed by a shark in Texas, 40-year-old Hans Fix, was surf fishing in waist-deep water off Andy Bowie Park on South Padre Island in 1962 when an unknown species of shark bit his lower right leg. “You’ll never go in the water again,” as they say.

Kissing Bugs

Also known as cone-nose bugs or chinches, these insects feed on blood at night and like to bite humans around mouths or eyes, hence their reputation for “kissing” their victims. About half of kissing bugs are infected with a parasite that can be passed to humans when the bug poops near the site of the bite, causing Chagas disease. Early symptoms—like fatigue, rash and loss of appetite—can last weeks but make the disease difficult to diagnose because they’re so similar to other illnesses. A little less than a third of bite victims go on to develop chronic Chagas disease, leading to an enlarged heart and other cardiac and intestinal problems, including an enlarged esophagus or colon, that make digestion difficult. The complications may not appear for decades. If left untreated, yes, it can kill ya.

Scorpions

Shake out those boots before you slide ’em over your stockinged feet—scorpion stings, while rarely fatal, can cause intense pain and swelling. The venom can trigger allergic reactions, leading to difficulty breathing and twitching muscles, as well as vomiting. (Pro tip: if one of these lobster-like arachnids ever hitches a ride to Garner State Park in the bag where you keep your air mattress, and then it pricks you on the palm, immediately stop setting up camp and promptly dunk your hand in the Frio.)

Fire Ants

As if Texans needed another reason to panic in the aftermath of Hurricane Harvey, viral videos revealed giant flotillas of invasive fire ants, a species that adapted to survive frequent flooding in its native South America by forming giant, teeming mats of up to 100,000 venomous ants looking for a dry place to reestablish their cursed colonies. When the waters recede after the next big flood, just be glad they didn’t land on you.

Mountain Lions

Also known as the cougar, panther, puma, or catamount, this powerful but shy wildcat could absolutely murder the average human if it wanted to. But it doesn’t want to. Only four mountain lion attacks on humans in Texas have been reported since 1980, all of them in remote areas of West Texas, and none of them were fatal.

Nine-banded Armadillos

Often oblivious to their surroundings as they noisily root around for insects and other grub, about 20 percent of these cute little armored creatures are carriers of leprosy, or Hansen’s disease, the ancient ailment seen as a curse from God during biblical times. Armadillos likely acquired the microbe that causes leprosy from humans sometime after Christopher Columbus showed up in the New World. They can retransmit it to humans who come into contact with them and are responsible for about one-third of leprosy cases in the U.S. each year, primarily in Texas and Louisiana.

“The important thing is that people should be discouraged from consuming armadillo flesh or handling it,” Dr. Richard W. Truman, a researcher at the National Hansen’s Disease Program in Baton Rouge, Louisiana, told the New York Times.

Which raises the question: are folks still paying $2.50 for ’dillos down in Hallettsville?

Whitetail Deer

A deer doesn’t have to crash through your windshield at 70 miles per hour to inflict harm on human beings: “Whitetail attacks on humans aren’t as rare as you may think,” reports OutdoorLife magazine. “And when they do occur, things can get ugly in a hurry.”

In 2007, the magazine reported, a Texas fisherman was watching as a nine-point buck swam across the Trinity River, shook itself dry, and its “demeanor changed from one of simple curiosity to one of pure malevolence.” The buck pawed the ground and charged, smashing the angler and tossing him into the river, where they tangled in the water. When they climbed out, the buck charged again, slamming him to the ground and stabbing his face with his antlers. The man’s nephew had to slit the buck’s throat to end the brutal blitz.

So, you know, watch out for those whitetails. And everything else.

This article has been updated to correct a mistake about the fire ant’s native habitat, and the location of the brown recluse’s fiddle-shaped pattern.

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Spider facts

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Some commonly asked questions and interesting facts about spiders.

Are huntsman spiders dangerous? They look so large and hairy.

Despite their often large and hairy appearance, huntsman spiders are not considered to be dangerous spiders. As with most spiders, they do possess venom, and a bite may cause some ill effects. However, they are quite reluctant to bite, and will usually try to run away rather than be aggressive. In houses they perform a useful role as natural pest controllers.

Some people may think of huntsman spiders as ‘tarantulas’. However, they are not related to the large hairy ground dwelling spiders that are normally called tarantulas. Both huntsman spiders and tarantulas are often portrayed as being dangerous and scary. This usually is the case in films or stories that deliberately present spiders in a frightening and unrealistic way. If you feel frightened of huntsman spiders because of this, perhaps you might like to learn more about their true habits and biology. In this way you might be able to reduce your fears.

How do you identify a wolf spider?

One of the diagnostic features of wolf spiders is their eye pattern which comprises three rows at the front of the carapace: four (smaller) eyes in the first row, two above the first and two above the second row. The diagram below (basically) shows this layout, face-on to the spider:

top of the head

bottom of the head

Wolf spiders also have a variegated pattern on their bodies, often including radiating lines on the carapace and scroll-like patterns on the top of the abdomen. The underside of the spider is grey or black, sometimes with white markings. They can have orange spots on the sides of their jaws.

As wolf spiders actively hunt for food they are likely to be found roving along the ground and they are more active at night. When spotlighted at night wolf spider’s eyes will glow green. Scientists use this method during invertebrate surveys.

Does Australia have a bird-eating spider?

The term ‘bird-eating spider’ usually refers to large spiders from the family Theraphosidae. These spiders are also referred to as tarantulas. In Australia the theraphosids are represented by the whistling spiders (Selenocosmia sp.). These ground-dwelling spiders are big enough to prey on small frogs and reptiles, but are not known to eat birds. They are also known as barking spiders.

Do we have tarantulas in Australia?

It depends on what you mean by the word «tarantula». Some people use it to describe the large hairy spiders of South and Central America. In Australia, the whistling spiders are also called Australian tarantulas, as they are related to the American spiders. However, the word tarantula is also used to refer to huntsman spiders.

Tarantula is derived from the name of a town in Italy, Taranto. This town is the original home of the wild dance called the tarentella. During the Middle Ages, the tarentella was thought to be the way to cure the bite of a particular spider. The symptoms — known as tarantism — included severe pain, swelling, spasms, nausea and vomiting, palpitations, and fainting, along with exhibitionism, melancholia and delirium. It was hard to determine whether an actual bite had occurred or if people were merely displaying some form of madness or hysteria. Scientists later determined that many cases might indeed have been the result of a bite, although much of the fierce dancing and extreme behaviour may reflect more about the social and sexual repression at the time.

The alleged spider that caused all of these symptoms was called a tarantula, but the species was incorrectly identified. The original spider identified by the people of the time was a wolf spider (Lycosa tarantula). However, it was subsequently shown to cause little serious results when it bit people. Finally, it was shown that the real culprit was a Black Widow relative, Latrodectus tredecimguttatus, known in Southern Europe as the «malmignatte». The symptoms of this spider’s bite (and of other Latrodectus species, including the Redback Spider) match the whole-body symptoms experienced during tarantism.

Information from: Hillyard, P. 1994. The Book of the Spider. Hutchinson, London.

Do we have scorpions in Australia?

Yes we do. Scorpions are common in gardens and forests throughout eastern Australia and are found under logs, rocks and in shallow burrows in earth banks. They are nocturnal — which is why we rarely see them — but they can be disturbed during the day, especially during the prolonged wet weather. There are also species that live in the desert and others that inhabit tropical rainforests.

What is the world’s most dangerous spider?

It is hard to define which spider in the world is the most dangerous to humans. Several spiders could qualify, depending on what you mean by dangerous. Do you mean the spider with the most toxic venom, measured by its effect on newborn mice or other mammals? Or do you mean the spider that has caused the death of the most people? Those that have the strongest venom may not be encountered by humans very often, or may even have trouble piercing human skin and so are not considered to be ‘dangerous’. Data are usually only kept on bites from spiders that are potentially deadly or cause severe reactions and these data are not recorded consistently at a national or international level. Here, we will define dangerous as ‘deadly’.

In summary, on current evidence the most dangerous spiders in the world are funnel-web spiders (Atrax and Hadronyche species), Redback Spiders and their relations (Latrodectus species), Banana Spiders (Phoneutria species) and Recluse Spiders (Loxosceles species). In Australia, only male Sydney Funnel Web Spiders and Redback Spiders have caused human deaths, but none have occurred since antivenoms were made available in 1981.

The Australian funnel-web spiders are among the deadliest spiders in the world in the effect their bites have on humans and our primate relations (although the bite has little effect on dogs and cats). There are many species of funnel-web spiders in Australia but only male Sydney Funnel-webs have caused human deaths. There have been only 13 deaths recorded from male Sydney Funnel-webs, but up to 30-40 people are bitten by funnel-web spiders each year. Mouse spiders may have venom that is as toxic as that of some funnel-webs, as some patients have had severe reactions to their bites, although no-one has been recorded as having died from the effects of a mouse spider bite. Antivenoms are available for both funnel-web and Redback Spider bites.

A group of spiders that is dangerous in many countries belongs to the genus Latrodectus in the Family Theridiidae. In Australia we have the Redback Spider (Latrodectus hasselti). In America, a common representative of this genus is the Black Widow (Latrodectus mactans). Antivenoms are available for both funnel-web and Redback Spider bites.

A deadly spider which comes from South America is the Banana Spider, Phoneutria species. In south-eastern Brazil between 1970 and 1980, more than 7,000 people were admitted to hospital with bites from this spider. An antivenom also exists for this species.

The Recluse or Fiddleback Spider is a deadly spider belonging to the genus Loxosceles. Recluse spiders are found in many parts of the world and have been introduced into Australia. The venom of this spider can cause severe skin necrosis (eating away of the flesh) and can be fatal although not many deaths have been recorded.

How many dangerous spider bites occur in Australia each year? Has anyone died from a bite recently?

There have been no deaths in Australia from a confirmed spider bite since 1979. An effective antivenom for Redback Spiders was introduced in 1956, and one for funnel-web spiders in 1980. These are the only two spiders that have caused deaths in Australia in the past.

A spider bite is not a notifiable medical emergency, so there are no Australia-wide statistics, but the following figures give an idea of the incidence of reported bites in recent years.

Approximately 2000 people are bitten each year by Redback Spiders

Funnel-web spider antivenom has been given to at least 100 patients since 1980. Antivenom is given only when signs of serious envenomation are observed. Many spider bites are ‘blank’, which means that no venom has been injected.

During 2000 the New South Wales Poisons Information Centre received 4,200 calls about spiders. However not all of these would have involved actual bites. Many reported bites are not able to be identified as definitely being from a spider, and it is nearly impossible to work out what species has caused a bite without seeing a specimen of the spider responsible.

Figures are from: Sutherland, S K and Nolch, G (2000) Dangerous Australian Animals. Hyland House, Flemington, Vic. 201 pp. ISBN 86447 076 3

  • Poisons Information Centre
  • The Children’s Hospital at Westmead
  • Locked Bag 4001
  • Westmead, NSW 2145
  • Emergency telephone: 131 126 (24 hours, within Australia only)
  • Administrative telephone: +61 2 9845 3111
  • Fax: +61 2 9845 3597

What spiders in Australia may cause ill effects if they bite you?

In Australia, bites from at least two kinds of spiders — wolf spiders and white-tailed spiders — in some cases cause skin necrosis (eating away of the flesh). However, neither spider has caused human deaths. There are also a number of others which are thought to cause the same problem, but research is still being done to find out exactly which species do so.

Bites from many Australian spiders can cause localised reactions, with symptoms such as swelling and local pain at the site of the bite, sweating, nausea and vomiting and headaches. All of these symptoms will vary in severity depending on the age of the victim, their health, and the amount of venom that the spider was able to inject. Have a look at our spider fact sheets to find out more about individual species.

Do white-tailed spiders cause the skin condition known as necrotising arachnidism?

There is an ongoing debate among toxicologists and spider biologists about the effects and dangers of white-tailed spider bites. Most of these bites appear to cause little or no effect beyond transient local pain. However a small number of cases do cause more extensive problems. Whether this is a result of the spiders’ venom or to bacteria infecting the wound at or after the time of the bite has not yet been resolved. It is also possible that some people may react badly to white-tailed spider bite, possibly because of immune system susceptibility or a predisposing medical condition.

  • Meier, J. & White, J. (1995) Handbook of Clinical Toxicology. CRC Press, Florida USA.
  • Whitehouse, R. (ed.) (1991) Australia’s Dangerous Creatures, Readers Digest Pty Ltd, Surry Hills NSW.
  • Sutherland, S. & Sutherland, J. (1999) Venomous Creatures of Australia, Oxford University Press, South Melbourne.
  • Isbister,G. & Greay,M. (2000). «Acute and recurrent skin ulceration after spider bite» Medical Journal of Australia 172, 20 March 2000, pp.303-304

How do I control white-tailed spiders around the house?

Beyond killing or removing all white-tailed spiders that you encounter, you can try a prey reduction strategy. White-tailed spiders like to feed on Black House Spiders (Badumna insignis) in particular, but will take other spiders too. This means that you should clean up obvious spiders around the house (outside and in). This involves removing spiders from around windows, walls and verandas (by web removal and/or direct pyrethrum spray). The condition of the roof cavity and the underfloor area (if raised) should also be investigated. (from Mike Gray, Arachnologist, Australian Museum)

What is the biggest spider in the world?

The biggest spider in the world is the Goliath Spider, Theraphosa leblondi. It lives in coastal rainforests in northern South America. Its body can grow to 9 cm in length (3.5 inches) and its leg span can be up to 28 cm (11 inches). (from: Carwardine, M. 1995. The Guinness Book of Animal Records. Guinness Publishing.)

What is the biggest spider in Australia?

Australia’s biggest spiders belong to the same family as the Goliath Spider. They are the whistling spiders. The northern species Selenocosmia crassipes can grow to 6 cm in body length with a leg span of 16 cm.

What is a Daddy-long-legs?

‘Daddy-long-legs’ is the common name for a particular group of spiders, but it is also used for a different group of arachnids — the harvestmen or opilionids. As a result, there is a lot of confusion about what people mean when they say ‘daddy-long-legs’.

The animal which most biologists call Daddy-long-legs, is a spider, Pholcus phalangioides, which belongs to the spider family Pholcidae, order Araneida, class Arachnida. It has two parts to the body, separated by a narrow waist. It has eight eyes and eight very long thin legs. Pholcids often live in webs in the corners of houses, sometimes in bathrooms. Daddy-long-legs spiders (or pholcids) kill their prey using venom injected through fangs. Digestion is external, with fluids being squirted onto the prey item and the resulting juices sucked up by the spider.

The other eight-legged invertebrates that are sometimes called Daddy-long-legs, are members of the order Opiliones or Opilionida in the class Arachnida. Another common name for these arachnids is ‘harvestmen’. Unlike spiders, their bodies do not have a ‘waist’, they do not produce silk and they normally have only one pair of eyes. They do not have venom glands or fangs, although they may produce noxious defence secretions. Most harvestmen eat smaller invertebrates but some eat fungi or plant material and others feed on carcasses of dead mammals and birds. Digestion is internal and some solid food is taken in, which is uncharacteristic for arachnids. You usually do not find harvestmen inside houses.

Are Daddy-long-legs the most venomous spiders in the world?

There is no evidence in the scientific literature to suggest that Daddy-long-legs spiders are dangerously venomous. Daddy-long-legs have venom glands and fangs but their fangs are very small. The jaw bases are fused together, giving the fangs a narrow gape that would make attempts to bite through human skin ineffective.

However, Daddy-long-legs Spiders can kill and eat other spiders, including Redback Spiders whose venom can be fatal to humans. Perhaps this is the origin of the rumour that Daddy-long-legs are the most venomous spiders in the world. The argument is sometimes put that if they can kill a deadly spider they must be even more deadly themselves. However this is not correct. Behavioural and structural characteristics, such as silk wrapping of prey using their long legs, are very important in the Daddy-long-legs’ ability to immobilise and kill Redbacks. Also, the effect of the Daddy-long-legs’ venom on spider or insect prey has little bearing on its effect in humans.

What are banana spiders and where are they found?

Banana spider is the common name given to large (3 cm body length) active hunting spiders of the genus Phoneutria (Family: Ctenidae). These spiders live in Central and South American rainforests. They are often found in rubbish around human dwellings, as well as hiding in foliage such as banana leaves where they sometimes bite workers harvesting bananas. They have a reputation for being quite aggressive.

Other names for this spider include: Kammspinne, Bananenspinne, Wandering spider, and Aranha armadeira.

The venom of this spider is neurotoxic — acting on the nervous system — and causes little skin damage. Symptoms of a bite include immediate pain, cold sweat, salivation, priapism, cardiac perturbations and occasional death. Research suggests it is similar in action to a-latrotoxin, which is produced by spiders of the Family Latrodectidae, such as the Redback and Black Widow Spiders.

Another spider that seems to have been given the common name «banana spider» is actually a completely unrelated species of orb weaving spider from Florida. This is a good example of why it is more useful to use scientific names when you are trying to find information on different animals or plants.

How do I find out about spiders in New Zealand?

The following New Zealand arachnologist (spider biologist) has offered to respond to inquiries from people interested in New Zealand spiders:

Dr Phil Sirvid
Entomology Section
Museum of New Zealand Te Papa Tongarewa
PO Box 467
Wellington, New Zealand
ph: +644 381 7362
fax: +644 381 7310

There is a book on New Zealand spiders: Forster, Ray and Lyn. 1999. Spiders of New Zealand and Their Worldwide Kin. University of Otago Press, ISBN 1 877133 79 5

What about white-tailed spiders in New Zealand?

Dr Phil Sirvid has this to say about white-tailed spiders in New Zealand:

«We have two species of white-tails in New Zealand — Lampona cylindrata and Lampona murina. They are both very similar in appearance, and can really only be separated from one another by viewing them under a microscope and examining certain features that aren’t apparent to the naked eye.

Both have been introduced from Australia.

L. murina has been in the North Island of New Zealand for [over] 100 years, and has also been introduced to the Kermadecs, Lord Howe Island and Norfolk Island. I wouldn’t be surprised if it’s in the Chatham Islands as well. In Australia, this species is recorded along the East Coast from northern Queensland down through New South Wales and Victoria.

L. cylindrata had only been found occasionally in the South Island until the 1980s. About this time it seemed to spread rapidly throughout the South Island’s main urban centres, and is known to occur as far south as Dunedin. This species is found along the southern part of Australia from Western Australia, through South Australia, Victoria and Tasmania, as well as in New South Wales and Queensland.»

How can I find out about spiders in North, South or Central America?

We do not have a scientist at the Australian Museum who is an expert on the spiders of the Americas. However you could look at some US spider web sites to see if they can help you. Or you could contact an American spider expert.

Spider biology facts

What is the function and origin of silk glands and spinnerets in spiders?

The development of spinnerets and silk represents a major evolutionary shift that has defined the biological and ecological uniqueness of spiders within the arachnids. Silk glands produce the silk that the spider uses for a variety of purposes. The spinnerets are the special organs that the spider uses to extract and manipulate the silk as is it is produced from the silk glands.

Spiders evolved from ancestors that had limbs on the abdomen, as did arthropods like crustaceans such as crayfish. In fact, one of their few living marine relatives, Limulus, the so-called ‘king crabs’, has retained abdominal limbs, which have been lost or greatly modified in terrestrial spiders and other arachnids. The spiders’ spinnerets are almost certainly derived from these ancestral abdominal limbs. In the basal (lowest) segments of spiders’ limbs are small excretory glands — the coxal glands — that secrete and excrete waste body fluids. It seems that the silk glands may represent highly modified excretory glands that now manufacture silk instead of waste products, just as the spinnerets represent highly modified limbs.

It is possible that an intermediate stage in this process could have been the production of a secretion that included pheromone (scent) chemicals put out by the spider as a primitive ‘signal line’ by which a spider could find its way back to its retreat burrow. This role was then taken over by the production of silk. The silk then became useful not only as a safety line, but also for prey capture, manufacturing egg sacs and a host of other activities.

[Modified from text by Dr Mike Gray — Principal Research Scientist (Spiders)]

Reference: Foelix, R.F.1996. Biology of Spiders. Oxford Thieme.

Why don’t spiders get stuck to their webs like the insects that they catch?

If you look at an orb-weaving spider in its web, you’ll notice that the body is held slightly clear of the web, especially when the spider is moving about. The spider has only minimal (but vital) body contact with its web via the claws and bristles at the tip of each leg. Compared to its prey, which crashes or blunders into the web, the spider has only a tiny portion of its surface area in contact with a very small amount of silk at any time. This is obviously an important factor when moving on a sticky web — the less contact the better.

Another important factor is that not all silk lines in a sticky web are sticky. For example, the central part of an orb web (where the spider sits) is made of dry silk, as are the spokes supporting the sticky spiral line, which the spider can use when moving around its web. It’s only when the spider makes a quick, direct charge across the sticky spiral to capture prey that it may cause some disruption to the web — but it never gets stuck.

Spiders also spend a lot of time grooming their legs. The spider draws the ends of its legs through its jaws to clean them of debris, which may include silk fragments. This is a very important maintenance activity that contributes to efficient function of the claws and bristles. As well as cleaning them, some secretions from the mouthparts may help make the leg tips less susceptible to sticking.

Why don’t orb weavers and other spiders fall off their webs?

Most web-building spiders have three claws on their tarsi (feet) — two combed main claws and a smooth central hook. The web silk is only grasped by the hook, and is pushed against serrated bristles, which snag the silk and hold it. When the hook is released by a special muscle, the elastic silk simply springs away from the hook.

Why can some spiders climb slippery surfaces such as glass or run across ceilings?

Many hunting spiders possess dense hair tufts called scopulae under the claws of their tarsi (feet). These scopulae allow many spiders to walk on smooth vertical surfaces, across ceilings and even window panes. Each individual scopula hair splits into thousands of tiny extensions known as end feet. These end feet increase the number of contact points of the tarsi with the surface, creating great adhesion. This is similar to the adhesion forces at work in vertebrates such as skinks and geckos, which can also walk on ceilings with ease. The scopulae can be erected or laid flat by hydraulic pressure through changes in the pressure of the hemolymph (blood supply).

Do spiders sleep?

It really depends on how you define ‘sleep’. All animals have some sort of ‘circadian’ rhythm — a daily activity/inactivity pattern. Some are active during the day — diurnal — others are active at night time — nocturnal/crepuscular. The periods of inactivity are characterised by withdrawal (to a shelter perhaps) and a drop in metabolic rate.

This applies to spiders as well, although no studies have been done to measure the period of time spent in such a state or at what times different species do it. It seems that spiders with good eyesight that rely on vision to capture prey may tend to be more active in daylight hours, whereas others that rely on snares/webs could be active at other times, but this is not necessarily the case for all species.

In cold climates, spiders ‘overwinter’, which means that they have a kind of hibernation period. Overwintering involves a drop in metabolic rate, where the spiders bring their legs into their body and remain huddled in a shelter during the coldest months of the year.

This ability to shut down for a long period of time indicates that they might be able to do it for shorter periods in their everyday cycle, which could be seen as a form of sleep or rest.

australianmuseum.net.au

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