IS
IT
DANGEROUS?
SNAKES AND OTHER POISONOUS
CREATURES
When are you the least likely to get
bitten by a viper?
The common European viper is cold blooded and has varying body temperature depending on how cold or warm the surrounding environment is. An easier way to put it is: the warmer it gets, the more ready they are to strike!
In cold conditions or in cloudy weather the snakes mostly keep still. By being exposed to the warming rays of the sun they can increase their body temperature and their metabolic rate and they become more agile. The viper's activity is therefore controlled by the surrounding temperature, which means that the risk of being bitten is greater when it is warm and sunny but lesser when it is cloudy and cold.
Snakes can be found almost everywhere except in very urban areas. Despite this you rarely meet them, since snakes prefer keeping away from us rather than risking confrontation.
SNAKE IN THE COMPOST? CONGRATULATIONS!
To have a snake in your garden has its advantages—you will not have problems with voles and mice. In springtime the snakes temporarily visit gardens when moving from their winter rest to summer territory. They quickly move along. If you have snakes around the house later in the season it can be assumed that they live on or near the property.
To lower the risk of permanent snakes in your garden you should make the area as unwelcoming as possible for them. Start by removing piles of sticks and cairns, seal eventual cavities in stone walls and house foundations, check basement ventilators for nests, keep the grass short and see to it that composts and piles of leaves are not too close to your house. Try to disturb the snakes as much as possible without hurting them. For example you can stomp around near them.
If you succeed in chasing of the snake's prey you can be fairly sure that you will not have a snake in your garden for a very long time. Sometimes you hear that tobacco can scare of snakes. It is true that snakes shun tobacco; at least they are very sensitive to nicotine. But even if you could afford to lay a string of tobacco around your property it would be washed away by the rain, as well as pose a risk of poisoning other animals.
SNAKES ARE ENDANGERED
In Sweden there are three species of snakes: viper and grass snakes, which are both common, and the southern and rare smooth snake. All Swedish snakes are endangered. According to law it is forbidden to kill, harm, capture, or in any other way collect a wild living specimen of any Swedish snake. It is, however, permitted to capture and relocate living vipers when they are found on your property. But neither the grass snake or smooth snake can be touched.
. . . if a poisonous snake bites another poisonous snake of the same species, nothing happens? A viper is in other words resistant to its own poison.
. . . vipers are excellent swimmers?
. . . snakes themselves cannot dig but like to use voles' passages and other already existing burrows?
“If you place a real absinthe wormwood by the front door no snakes will come into your house.” Unfortunately this is only an old tale. The person who finds a herb that actually works is encouraged to contact the On Duty Biologist!
IF YOU GET BITTEN—CONTACT A DOCTOR!
Around 200 people are hospitalized yearly due to being bitten by a viper. Between 20 to 30 percent of them have moderate to severe symptoms. The reaction after being bit by a viper varies a lot depending on how much poison you have in you. In almost half of the cases no symptoms will occur, which is because no poison was injected. Usually you see two small marks 0.02 to 0.03 inches apart from each other.
It is highly unusual for humans to die from snake bites. But the poison from the viper can be dangerous for a hypersensitive person. The poison control centers recommend persons bit by a snake to contact a doctor.
HAVE IN MIND
. . . that suitable shoes or boots can protect against snake bites. Most people get bitten in the foot or ankle.
. . . never pick up snakes.
“If you are bitten by a viper baby in the spring, you will die within two days if you are not treated.” The most poisonous snakes are not the little babies, but the biggest snakes since these have the most venom.
SNAKE OR LIZARD?
The little slow-worm can easily be mistaken for being a snake since it does not have any legs and also moves like a snake. But it is, in fact, a lizard. Slow-worms are different from snakes because they have eyelids and blink like other lizards, their ear opening is visible and they shed their skin in many pieces instead of just one like snakes do. Underneath the body the slow-worm has small scales—just like they have on top of the body. Snakes have (almost always) extra large and wide scales under the body.
Are there poisonous fish in Sweden?
There are a variety of tales about the the toxicity of fish: The ruffe has toxic mucus, the zander has toxic blood, the perch has poisonous dorsal fins and the weever has toxic thorns on its operculums. Sure proof can only be found about the weever's toxicity.
The ruffe is said to have toxic mucus, but probably all fish mucus has some sort of antibacterial function. The perch supposedly has toxic dorsal fins which is doubtful, although it could be considered that the thorns, like other sharp objects, can give secondary infections. The claim that the zander would have toxic blood is entirely unsupported.
But the weever's toxicity is quite well documented. This little fish has a toxic thorn on each operculum and all the spines in the front dorsal fin are toxic. The thorns and their poison are only used in self defense and not when hunting preys. When the fish feels threatened the operculums flip out and the front dorsal fin is raised. The thorns are thick and can pierce through thinner materials and also human skin. The operculum thorns as well as the spine contain a white glandular tissue. After an injection of poison the thorn in question is immediately filled up again. Note that even dead fish have poison in their thorns.
Accidents often occur when the fish is being removed from the net but it sometimes happens that a swimmer accidentally steps on the fish. The poison causes a local reaction with immediate intense pain, swelling and discoloration of skin. Untreated pain can last for a day. The swelling can last for weeks and in rare cases months. Symptoms of headache, dizziness, chills, sweating, and nausea occur. Bacterial infection can occur as a complication.
Is it possible to die from a jellyfish?
There are jellyfish that are extremely toxic, such as the infamous box jellyfish, which has killed roughly 5,500 people since 1954, when records were first kept for jellyfish fatalities.
Along the Swedish west coast the moon jelly, lion's mane jellyfish, blue jellyfish, compass jellyfish and the barrel jellyfish are naturally occurring species. In the Baltic sea there is only the moon jelly. Compass jellyfish, blue jellyfish and the lion's mane jellyfish almost always only cause local symptoms, in the shape of a burn-like skin irritation.
In tropical countries there are considerably more toxic species. Some of these are the Portuguese Man o' War, box jellyfish and the Irkudanji jellyfish. These jellyfish, also known as “stingers,” are each year involved in serious incidents with severe poisoning, and can even cause deaths.
DEFENSE OR ATTACK?
When it comes to toxic animals there are two types: those who use their venom as a defense against attackers and those who use it to kill prey and get food. For animals in the sea the venom works as a defense function for most species while the animals on land often use the venom as both a tool of defense and an attacking weapon.
OUR FRIENDS WITH A STING
How many stripes does a wasp have?
It is possible to say that female wasps have twelve stripes— six black and six yellow—while the males have fourteen stripes. The number varies greatly, however. In Sweden we have twelve species of social wasps and they all look a little different from each other.
All wasps have a rear body that generally is striped in yellow and black. Usually there is at least a yellow part and a black part on the rear body segment, even if they are not always in straight lines. The black parts (which sometimes are in the shape of dots) are always closest to the middle body segment but can sometimes be completely missing, so that the rear body looks yellow. However the rear body can sometimes be almost completely black, especially in north of Sweden where the black pigments can overtake the yellow. Black wasps are a rather organic adjustment to the colder climate: Wasps are cold blooded animals that need to be heated by the sun and the black color makes the body temperature rise faster.
STOP WAVING YOUR ARMS!
The best advice to avoid being stung is to act normally and not wave your arms around the wasps. Think of how wasps actually are useful beings! Since they are predators they catch different kinds of insect larvae as food for their own larvae. Tat way they keep troublesome pests away from berry bushes and fruit trees, and are very useful in our gardens. Wasps are not nectar specialists, but find all sorts of plants with easily accessible nectar, so they are quite good pollinators.
If you still do not want wasps around you it is wise to remove old nests during the winter. Wasps do not reuse their old nests and it is unlikely females will hibernate in it, but they do like to build a new one that is connected to the old one. Therefore make sure to fill any cavities, so the wasps cannot return to the same place next summer. There are also purely sanitary reasons to clean out old nests; the leftovers from the old one can attract skin beetles and other pests we do not want around us.
TIPS FOR A WASP-FREE GARDEN PARTY
Wasps are predators and therefore like everything we eat—meat, fish, seafood, and other food rich in protein. Vegetables, on the other hand, they will not eat. Wasps need fluid, and they drink nectar that is found in most plants' flowers. The nectar is sugary, and therefore wasps are attracted to anything that is sweet. This is why you should not let fruit fallen from trees lay around your garden.
› Only serve vegetarian food and only drink ice water
› Avoid deodorant, cologne, and perfume
› Do not wear Hawaiian shirts, or dresses and blouses with flower patterns
› Avoid sudden movements, waving, and strikes
› Do not stay close to a wasp's nest. Most of all do not sit on or close to the nest entrance path
› Do not be afraid! If you are scared you will send out alarm pheromones that can attract wasps
SMALL BUMBLEBEES CAN ALSO STING
Just like bees and wasps, bumblebees have a stinger connected to a venom sac. Just like regular bees, bumblebees will sting if they are annoyed. The bumblebee poison has a burning effect, which is why you say that bumblebees burn.
There are a number of differences between bumblebees and bees: Bumblebees fly in lower temperatures, even at 50°F, while bees need at least 53.5°F to be able to fly. Tat means that bumblebees are up earlier in the morning
and later at night compared to bees. Bumblebees, on the other hand, fly shorter distances and thus have a smaller territory. This is likely one of the reasons that bumblebees have been proven to be better at pollinating greenhouses than bees. Bumblebees also lack the ability to inform other individuals within their own community of a good source of nutrition. Some bumblebee species have longer tongues than bees and can therefore also drink from flowers with nectar deep inside, such as red clover.
Is it possible to predict a wasp filled summer?
As an On Duty Biologist, I often receive questions of a predicting nature, like: Will there be many wasps this year? Of course it is hard to tell how the year will turn out, but it is possible to try to make a somewhat qualified guess.
Last year's conditions can usually give you clues: If the late summer was cold and rainy, there is a high chance that many wasp communities collapsed and went under. There was no time to hatch very many productive offspring, since it is not until the late summer that the fertile males and females are hatched. Earlier in the season only sterile workers have been hatched, which help to build the nest, find nectar, and in other ways make it nice for others that live in the community.
When the reproducers mate the male dies. But the female, also known as the queen, finds a place safe from cold to rest over the winter. Of the old society, everyone dies except the females that have mated to pass on the species to next year. Mild winters with few and short periods of cold are favorable to the hibernating queens. Humid weather also produces a risk of mold.
A disastrous late summer and winter period can however be followed by an unusually favorable spring and early summer. Lots of sun, heat, and suitable food can make it possible for the nests that have survived, against the odds, to thrive and evolve beyond all expectations. Tat is when all the predictions fail. It is not easy to always be right but at least you can do your best!
. . . the wasp sting lacks barbs and therefore stays on the wasp after it has stung? In other words it can sting several times. The honey bee's sting has barbs and gets stuck on whoever is stung. Therefore the honey bee can only sting once, and dies thereafter.
. . . that bumblebees collect nectar and pollen and produce honey, just like bees?
. . . our largest species of wasp is the hornet? Although it is big and buzzes loudly as it flies it is our most peaceful wasp! It prefers a hole in an old tree, or perhaps an attic to live in.
“Be careful, the bumblebee will burn you!” No, but a sting from a bumblebee is perceived differently than one from a bee or wasp is because it produces a burning sensation. Maybe the myth originated to stop small children from trying to catch cute bumblebees with their hands. In a situation like that they would sting!
MYTH AND TRUTH ABOUT STRONG ANTS
“In Asia there are ants that are so strong that they can carry away a child!” The truth is that there is not an ant in the whole world that can carry away a child!
The load that nordic ants can carry to the anthill in their jaws is fairly easy to collect and weigh. According to a study at the Swedish Museum of Natural History, it is mostly dry parts of plants that can weigh between 0.0002 ounces to 0.002 ounces. If you compare the heaviest load with an ant's weight, which is about 0.0004 ounces, the result is that they can carry up to seven times their own weight. But despite their strength ants cannot jump. Tat is because they can only move their opposite legs at the same time, and never in pairs.
Ants also carry other things to the anthill, like small stones (that weigh up to 0.0015 ounces), dead insects (up to 0.0017 ounces), and rowan berries (at the most 0.0028 ounces). The ants' most common building material, pine needles, weigh about 0.0005 ounces each. Together many ants can carry even heavier loads; for example, a dead hornet, which weighs about 0.0074 ounces.
BLOODSUCKERS AND BATS
Why are some people bitten more often by mosquitoes than others are?
All female mosquitos have to suck blood, in order to obtain enough protein to produce eggs. Why mosquitos sting some people but not others is unknown.
When the female mosquito needs blood, several of her senses are involved, including vision, the sensory system, and smell. Smell is the most important factor when it comes to the female mosquito's search for blood. Depending on wind and humidity, the smell of the human body can reach her from a distance of about 65 feet. Carbon dioxide in the breath, lactic acid in sweat and from the skin, and octenol in sweat, are among the specific substances that attract mosquitoes.
The fact that carbon dioxide from our breath attracts mosquitoes, even at great distances, has been known for a long time. Carbon dioxide also has the ability to increase other smells. For example, mosquitoes are more attracted to the combination of carbon dioxide and lactic acid than only lactic acid or only carbon dioxide. Octenol attracts some mosquitos very strongly while others are repelled and keep their distance. This substance often produces a better reaction when mixed with carbon dioxide.
A SENSE FOR HUMIDITY AND HEAT
The air surrounding a human is a little warmer and more humid. This seems to attract the mosquito. The relative humidity only needs to increase a little in order for the mosquito to feel it. The mosquito is however only attracted to the increased humidity when it is followed by smells or a higher temperature.
Not only humans are affected by mosquitos. Any animal that the mosquito can get near enough to suck blood from will lose a few drops.
THE WORLD'S MOST DANGEROUS ANIMAL?
The small Anopheles is probably the world's most dangerous animal. Even if the mosquito in itself is not dangerous, it spreads a parasite that causes malaria, which can be a terminal illness.
. . . a mosquito that is full of blood increases its weight from 0.0001 ounces to 0.0003 ounces? Tat is a weight gain of 333 percent—and it can still fly!
. . . the Tipuloidea is a big mosquito? But it does not sting!
. . . that only female mosquitoes suck blood? The males live on the nectar that they drink from flowers.
IF A MOSQUITO IS HIT BY A RAINDROP, WILL IT DIE?
The body of a mosquito is rounded so that its shape will prevent it from hitting the ground because of a raindrop. It also has a very strong outer skeleton that is both jointed and very tough (chitinized), which makes it difficult for a drop to affect the mosquito. In addition, the mosquito has hair, bristles, and a water-repellent layer on its body. All of this makes the possibility of the mosquito being killed by a raindrop very small. Although it could have bad luck of course.
What are ticks good for?
First of all, all animals and plants exist for their own sake! But ticks can also be useful to others by serving as food for birds, spiders, and amphibians.
Ticks are parasitic beings that work as vectors in the ecosystem. Tat means they transmit bacteria, viruses, and microorganisms from one host to another. Likely they are helpful in regulating the host population by spreading disease, but this is still not very well documented. You can say that ticks have found their own niche in the ecosystem that is not being used by other animals, which makes them successful.
A tick goes through many different stages of development during its life cycle: The first active stage is the larva that can be up to about 0.02 inches. When the larva hatches from the egg, it has six legs and needs a meal of blood before it can develop further. After having sucked itself full of blood from a suitable host, it lets go and falls down to the ground. Here it sheds its skin and moves along to the next stage of development—the nymph. A tick nymph has eight legs and grows up to 0.04 inches long. The nymph also needs a meal of blood before it falls down to the ground, sheds its skin, and moves along to the last active stage—a grown tick with eight legs.
Full-grown male and female ticks mate with each other, but in order for the fertilized eggs to develop inside the female she needs to suck more blood. The male dies after mating without having sucked blood. A female tick can lay up to 1,000 to 3,000 eggs, which are laid one at a time in dense vegetation.
ANESTHESIA!
When a tick bites it first injects an anesthetic substance in its saliva, which prevents the host animal from noticing the bite. How long it is stuck depends on what stage the tick is in. The larvae can suck blood for 3-5 days, while grown females can be stuck from one to two weeks if they are left alone. The tick can use the human as a host in all active stages.
Since ticks are sensitive to dehydration you usually find them near wet areas, often in dense, medium high grass. As a rule they sit at the tip of a grass straw or in low bushes where they can easily catch onto hosts passing by with outstretched front legs. When they have enough blood they let go and simply fall of the blood giver. How fast the tick then needs to find a new host depends on the weather, or rather the humidity, and what stage it is in. The bigger the tick is, the longer it can manage without a new meal of blood.
DIFFICULT TO EXTERMINATE
Ticks have very few natural enemies. They are eaten by birds, spiders, frogs, toads, and lizards—and they are attacked by parasitoid wasps. Our winters rarely cause the ticks any problems. The combination of intense cold and bare ground can be devastating, but usually the weather is mild or a protective layer of snow covers the ground. Two factors that can reduce the number of ticks are if the climate were drier and had fewer hosts, both wild and domesticated. But since both of these things are beyond human control, the possibility to impact the number of tics is very small.
. . . most ticks that suck blood from humans, dogs, and cats belong to the species of common tick, Ixodes ricinus? There are also other species of ticks that can bite us but about 95 percent of all attacks are made by a common tick.
. . . the best and easiest way to remove a tick is to as fast as possible pull it of with the help of a special tick remover or tweezers. The quicker you remove it, the less the risk that the tick has any time to transfer infectious substances.
Are bats dangerous?
No, but you should treat them like you treat all other wild animals—with respect. If it is necessary to move a bat you should use gloves. Bats usually bite if you hold or squeeze them as a natural behavior when they feel threatened.
Bats do not attack humans. However, they can become worried and start to fly very close if you approach a colony. When bats hunt prey at night, they sometimes come very close since the heat we send of attracts insects, especially mosquitoes, and we become a walking smorgasbord.
Bats are an important part of biodiversity. They are a successful animal group with many different species and a large geographical spread. At the same time bats are very sensitive to changes in the landscape, which means that the spread of human habitats has caused a decrease in bat populations.
All bats are endangered in Sweden. They are also protected by a European convention—Eurobats—that includes the bats' nesting places and important hunting territories. It is therefore prohibited to kill, harm, or disturb bats.
THEY OFTEN LIVE IN OUR HOUSES
Bats probably always shared property with us humans. Some species simply prefer to live in houses that give them better protection and in addition are warmer and less windy than tree cavities, outdoor basements, or other natural caves. Our houses can be used both during the winter rest and as a summer home when babies are born. As a rule you can find the bat colony on the south side of the house, since it is the warmest. Normally bats do not harm the house they live in. They cannot gnaw and they do not build nests or destroy the house any other way, but only use the small spaces that are already there.
Usually bats hang in the attic next to a chimney or under the tiles or tin roofs. They will not do any harm there and these spaces are drafty enough to prevent any bad smell. If the bats create big colonies in the central walls of the house it can start to smell because of poor ventilation. It can also be noisy during the summer months when babies are in the colony.
STRANGE SOUNDS AND BED BUGS
The female bat usually gives birth to her baby in the middle of the summer. The baby suckles for three to four weeks until it is ready to fly and can start practicing to hunt insects. During their initial growth stage, the female calls the baby with sounds that humans can hear as well. The animals also move around inside the colony, and a scratching and shuffling sound can occur as they move around. In old houses the bedroom is often situated in the same direction
as the bats prefer, south or southwest. When nothing but a thin bedroom wall separates the rooms there is of course a risk of trouble since bats and humans have different daily rhythms.
Bed bugs can sometimes cause a problem in connection to bats. The best time to exterminate bed bugs is in the middle of June or middle of August, so that all bats will have had the time to leave.
CHOOSE THE RIGHT TIME FOR REMOVAL
It can be very difficult to get rid of bats. The only safe way is to renovate the house so that the bats can no longer find a way in. The tiniest bats need an opening only around half an inch big to get through. Covering vents and other openings with fine mesh nets, such as mosquito nets, can therefore be an alternative method of keeping the bats away. Note that you need to be entirely sure that all bats are out of the house before you start!
Between the first of June and the last of August, you should not do anything at all, since that would disturb the bats while they are giving birth to their babies. If you do it anyway, there is a high probability that you will lock adults and babies inside the house, leading to starvation. Aside from the fact that this method of killing is neither legal nor humane, the dead animals will likely cause serious odor problems.
BE CAREFUL
In Sweden there have been recent findings of antibodies against bat rabies, but not the virus, in individual Daubenton's Bats. Tat means that the animals have encountered bat rabies during their lifetime and that the immune system has been activated. It is recommended that people who work with bats be vaccinated against rabies, and you should always wear gloves if you touch a bat.
Like other mammals, the bat has a variety of different parasites. Most are specific to bats and do not care at all about humans. If you have bats in the attic or roof tiles, there is no risk whatsoever that the pests will affect humans in the house. If you on the other hand share space, for example if you sleep in a loft directly under the roof tiles, there is some risk.
In Sweden bats live only on insects, and their feces therefore mostly contain parts of insects, such as shells and wings. It is completely harmless. Their feces is also very rich in nitrogen and may advantageously be used to fertilize your flowerbeds.
TO SPOT A BAT
The very best way to experience bats is to be with an expert. At dusk you can also stand outside of a house or cave where you know that bats live. If you are lucky you will spot their dark silhouettes against the still-light night sky as they fly out.
Do vampires exist?
Yes, but not in Transylvania! There are three species of vampire bats; all live in South and Central America. One of these bites a hole in the skin and licks blood from mammals and the other two do the same thing to birds. The species that licks blood from mammals, Desmodus rotundus , can cause problems for farmers since it sometimes spreads rabies. The difference between the vampires' diet and the regular bats that eat mosquitoes is really not that big: mosquitoes brimful with mammal blood are practically on a blood diet!
. . . bats are big consumers of insects and very effcient mosquito hunters? A scientist in England calculated that a bat can eat up to 7,000 mosquitos during one single night. Tat is almost twice as many as a swallow!
. . . that bats are an important part of biodiversity? As much as twenty percent of the land-dwelling species in Sweden are bats.
CREATURES WITH EIGHT LEGS
What is the deal with spiders and their poison?
Almost all spiders are toxic predators but only a few are dangerous to humans. Out of the world's 35,000 known spider species, only a couple hundred have a bite that is powerful enough to affect us.
Spiders use poison as fast as possible to make sure that their prey is paralyzed or to kill it, and to start digestion. The poison is usually adapted to the type of prey the spider is catching—although no spider aims for humans as their victims. The roughly 700 spider species in Sweden are normally not dangerous to us humans. But some species can, if they are carelessly handled, be provoked to bite. None of them have enough toxins to cause any serious harm and most of them have too weak of a bite to cut through our skin. There are however a few large spiders whose bite can be painful and cause local reactions, likely caused by poison and/or infection.
SOME SWEDISH SPIDERS THAT CAN BITE:
› European cave spiders
› Garden spiders and other large species of the orb-weaver family
› Wolf spiders
› Raft spiders
› Common house spiders
› Water spiders
› Yellow sac spiders
› Wasp spiders
THE WORLD'S MOST DANGEROUS SPIDERS
There are many theories about which spiders are the most poisonous. Here are some:
› The Australian funnel-web spider Atrax robustus, which is often found in damp basements or near swimming pools
› The North American brown spider Loxosceles recluse
› The South American banana spider Phoneutria nigriventer
› Latrodectus spiders, for example the infamous black widow Latrodectus mactans
› The Brazilian Phoneutria fear is said to have the most toxic venom of all spiders
HEALING DANCE
The tarantula wolf spider, Tarantula fasciiventris, gave rise to the tarantella dance. The spider is, despite its size and frightening appearance, only dangerous to the human in especially unfortunate circumstances. Its poison has wrongly been considered to be dangerous to humans and it used to be believed that the only cure for the bitten person was to dance until exhaustion—a tarantella.
Why do spiders spin webs?
Almost all berry pickers have at some point been annoyed with the invisible catching nets that are everywhere in the woods and that get stuck in your face and hair when you walk between two trees.
During almost their entire life, spiders are involved with spinning threads. Aside from producing nets for catching prey, the threads have many other functions. They are used for making nests, passages, constructing the cocoon around the female spider's eggs, camouflaging, and even protecting against the sun. Many spiders trap their prey in threads that make them look like mummies. Before mating, all males weave a special container in which they deposit the sperm that is going to be transferred to the female. Some species' females weave a cocoon around the male after mating. With others, for example crab spiders, the male weaves around the female before they mate.
Most spiders also produce a thread that is used as a safety line. It is secreted when the spider crawls of the web and is regularly attached to the surface with a little dab of glue. Many small spiders and spider babies use the thread for flying, as they can drift of with the wind attached to it, which is a way for the spiders to spread out to new places.
SPIDERS IN THE CEILING
Spiders have claws on their feet. You can see this with a magnifying glass. After that it gets more complicated,
because spiders also have thousands of small hairs on their feet. These can only be seen in a very strong microscope. On one spider 78,000 hairs were found on each foot. All of these small hairs make it possible for the spider to walk on the ceiling because the hairs increase the friction against the surface—so the more and smaller hairs the better. Calculations were made considering the spider's weight (0.0005 oz) and under the circumstances that it had all eight legs in the ceiling at the same time with a total of 624,000 small hairs. This gives the spider a safety margin of 160 times, meaning the force that holds it on the ceiling could manage to hold a spider that is 160 times heavier. Flies use a similar method to walk on the ceiling.
A WALKING SILK FACTORY
In the rear body of an orb-weaver spider, there are up to seven different types of glands that produce threads. The most important are ampullate, which makes the threads on the edges of the wheel web; piriform, which produces silk to keep the separate threads of the web together; aciniform, whose threads are used to mummify prey and produce the container for semen and the tubuliform, which produces silk for the egg cocoon. This last gland does not exist on male spiders.
. . . many spiders move around by using the wind? They climb a tree or another place high up and let out threads that the wind catches on to. Tat way the spiders can end up anywhere.
. . . there are spiders that live in water? One of them is the water spider, which weaves a little diving bell that it fills with air in order to breathe under the surface.
. . . many spider species in Sweden live for one to two years, but some foreign tarantulas can live more than 20 years?
. . . ticks are arachnids? Scorpions, pseudoscorpions, and acari are also included in the arachnid family.
. . . arachnids' bodies are split into a front body part and a rear body part. Tat separates them from insects, whose body is split in three, since the head forms a body part of its own. Arachnids have four sets of legs; insects only have three sets.