Make a list of the four things you're most afraid of, and the highest votes are: snakes, spiders, fear of heights, and confined spaces.
In the questionnaire survey, spiders were on the list of fears. Fear of spiders is innate, our ancestors lived with spiders for 60 million years, and the fear of being hurt by spiders is rooted in instinct and bequeathed to us.
When pictures of spiders are shown to 6-month-old babies, their pupils are visibly dilated and the pressure increases dramatically. If you replace the spider picture with a picture of a flower of the same color and size, the baby's stress is relieved.
There are 45,700 species of spiders in the world, and most of them are venomous except for a few that are now non-venomous. The most frightening thing about the spider is not its strange eight eyes and eight legs, but its venom.
How many people did poisonous spiders kill before their ancestors carved fear into our instincts? You may not believe it, but in the last century, there were 100 people poisoned by spiders. 100 people in a hundred years, less than the mortality rate caused by any accident, including the lowest probability lightning death rate (in the United States alone, an average of 50 people are killed by lightning in a year).
Spiders are far less terrifying than we think, and so are the most poisonous spiders in the world. The top three most venomous spiders in the world are: the Sydney Funnel Web Spider, the Brazilian Roaming Spider, and the Black Widow. Let's start with the most famous Black Widow, skipping the roaming spider, and finally the most poisonous funnel web spider.
<h1>Misunderstood Black Widow</h1>
Black Widow gets its name from the fact that females eat males after mating. Males who are much smaller than the female, after mating, can not run mates stronger than him, and can only fill the female's belly and become nutritious to raise the next generation.
There are 31 species in the genus Black Widow, which vary greatly in size. They have traveled far and are found everywhere in the world except Antarctica. A hallmark of the genus Black Widow is a red mark on the round belly of the female spider.
Pictured above is the North American Black Widow (Latrodectus hesperus), commonly known as the Western widow. The males of these spiders are only 5 mm long, and the females are 3 times larger, with a length of 1.5 cm. Males are harmless to people, but females are different. The female black widow has an unusually large venom gland that secretes toxins that directly attack the nervous system of vertebrates, which are 15 times more toxic than sidewinders.
Is the black widow who does not even spare her spouse a second to kill humans?
Biologists (David Nelsen and collaborators) have captured 43 large female black widows from the wild for experiments.
They made several prosthetic fingers out of gelatin to provoke the spider. The degree of gelatin finger provocation is divided into three levels: light, medium, and severe.
Lightweight: Poke the spider with a single gelatin finger. Poke and the spider walks away. The spider ignored the fingers, did not bite it, and did not pop the spider silk defenses.
Medium: Gelatin fingers poke the spider once a second for one minute. Poking may be unintentional, but if you keep poking, you are deliberately violating. In the face of the violation, half of the 43 spiders ejected spider silk against their fingers. Other spiders simply shrunk into a ball and lay on the ground pretending to be dead. Only one spider showed its teeth and tried to bite its finger.
Severity: Pinch the spider with two gelatin fingers for 10 seconds. The whole body was restrained, and the spider began to panic. 60% of spiders open their mouths and bite their fingers, averaging 2.7 bites per person. But in this experiment, some of the 43 spiders were pinched to death by fingers. That is to say, in the case of being pinched to death, the black widow only opened her mouth to bite.
Although the spider bites back, every time it bites, black widow doesn't necessarily unleash its ultimate weapon, venom. The experimental team continued to do experiments, replacing the gelatin finger with a vial with a thin film sealed at the opening, and using the vial to provoke the spider. It turned out that when you pinched the spider's leg, most of the time it only bit you dryly, generally not releasing venom. If you release poison, only a small amount of venom is placed. When you pinch the belly of a spider, you are already a serious threat to the spider. The spider can escape if one leg is broken, and the belly is broken. At this time, the spider will release venom when it bites you, and the amount of venom is twice as large as when it clamps the leg. However, even if you pinch the spider's belly, it will not release all the venom at once to attack you.
Spiders can accurately control the amount of poison released, whether it is attacking or counterattacking, it will not use up all the venom at once. Venom is a spider's weapon to capture food, and it is used carefully. Large crickets give a little more poison, small fruit flies give a little less poison, and each meal has a planned amount of venom. If the venom is used up at once, it will take weeks to replenish the venom, which also means that spiders without venom weapons may starve for weeks.
You are not a spider's food, and it is reluctant to waste precious and limited amounts of venom on you.
In the United States, there are 2,200 documented bites of black widows each year, but most of them do not need to go to the hospital. Some bites are just dry bites, and even venom-releasing bites are not serious. When you are bitten to seek medical treatment, you are given a shot of anti-spider venom serum for pain relief, not for life-saving purposes.
Although the Black Widow is 15 times more toxic than the Rattlesnake, it is too small to store venom and does not endanger human life.
The Poisonous Spider's third-ranked Black Widow title far outweighs its horror, taking its name from a male that is eaten, rather than turning a human into a black widow after a black widow bites. [Headlines • France is Bacon unauthorized reproduction is strictly prohibited]
<h1>Sydney funnel web spider</h1>
Compared to the timid black widow, the Sydney funnel-web, the head of the poisonous spider, is larger and more aggressive.
The Sydney funnel web spider is found within 100 kilometres of Sydney, with a body length of 1 to 5 cm and a leg length of 6 or 7 cm. Males are slightly smaller than females, but have longer legs. Unlike Black Widow, the Sydney funnel web spider is more toxic to males, the male is 6 times more toxic than the female, and the biting and deadly Sydney funnel web spider is all male.
Since the development of the Anti-Spider Venom Serum agent for the Sydney Funnel Web Spider, no one has been killed under its mouth. The most dangerous one was rescuing a 10-year-old boy in 2017. The boy was bitten by a Sydney funnel web spider hidden in his shoe and it took a total of 12 bottles of anti-venom to get him back.
When provoked, the funnel web spider clings to the victim and repeatedly plunges its fangs into human flesh to release venom. One of its venoms is a toxin called atracotoxin (atracotoxin), a neurotoxin that is extremely harmful to humans and primates. However, this toxin does not affect the nervous system of other mammals.
Arachnid is a biologically active polypeptide that is a compound made from the dehydration of multiple amino acid molecules. Arachnoid venom induces neurons to spontaneously and repeatedly release electrical signals, and the body will vomit, sweat, droole, breathing difficulties and other reactions, and when severe, life is in danger.
But the Sydney funnel web spider venom is not only harmful, it can also save lives. Professor Glenn King of the University of Queensland has proposed a polypeptide called Hi1a from arachnosynnes, which is effective in treating stroke.
The mortality rate and disability rate of stroke are very high, and the annual stroke mortality rate in China accounts for one-fifth of the total mortality rate, and no effective measures for the treatment of stroke have been studied.
In stroke cases, cerebral infarction caused more than 85% of ischemic strokes. Cerebral ischemia also means hypoxia, which forces the brain from the metabolic mode of normal cells (oxidative phosphorylation) to an oxygen-free glycolysis. The production of acids in the metabolites increased, the extracellular pH decreased from 7.3 to 6.5, and acid-sensitive ion channel 1a (ASIC1a) was activated. Acid-sensitive ion channels are the main sensors of the mammalian brain and a key factor in causing neuronal damage.
Simply put, acidosis occurs in the brain during cerebral infarction, which damages the cranial nerves in a large area.
Hi1a blocks acid-sensitive ion channels in the brain and inhibits acidosis that occurs after cerebral ischemia. Professor Jin's experiments confirmed that a one-time injection of a small dose of Hi1a into laboratory mice that caused strokes in cerebral infarction can reduce the area of cerebral infarction and protect neurons in the brain. As long as the drug is administered within 8 hours after the stroke in mice, the area of cerebral infarction can be significantly reduced. Moreover, the experiment also confirmed that no side effects of Hi1a were found during the 72-hour observation period after intravenous injection of Hi1a polypeptide in mice.
In the case of a stroke, the sooner the treatment, the better. If Hi1a, which can be administered in time on an ambulance and has no side effects, can be developed, it will be a major breakthrough in stroke treatment.
The most poisonous spiders are finished, and the home spiders that have the most contact with us are even less terrible. In fact, compared to your fear of spiders, spiders are more afraid of you.
Under the same roof, spiders live quietly far away from you. Even if you fall asleep, the spider will not come to you. Even if you don't snore, don't talk about dreams, and don't turn over, your breathing, heartbeat, and heat are enough to deter the spider.
Household spiders eat all kinds of bugs, and the bugs in the home are all pests except spiders.
A spider that can kill pests and bring its own venom to cure diseases has no better partner than it.
Our fear of spiders is far more than the facts themselves.
#Wonderful Animals # #这很科学 #
Resources:
1：“Itsy bitsy spider: Fear of spiders and snakes is deeply embedded in us”https://www.mpg.de/11671257/fear-of-spiders-innate
2：D. R. Nelsen, W. Kelln, and W. K. Hayes, “Poke but Don’t Pinch: Risk Assessment and Venom Metering in the Western Black Widow Spider, Latrodectus Hesperus,” Animal Behaviour 89 (2014): 107–114
3：“The Strategic Use of Venom by Spiders”，
4：
5： “Potent neuroprotection after stroke afforded by a double-knot spider-venom peptide that inhibits acid-sensing ion channel 1a”，
6：Stuber, Marielle & Nentwig, Wolfgang (2016). "How informative are case studies of spider bites in the medical literature?". Toxicon. 114: 40–44.
7：Diaz, J.H. (August 1, 2004). "The Global Epidemiology, Syndromic Classification, Management, and Prevention of Spider Bites". American Journal of Tropical Medicine and Hygiene
8: Image from Wikipedia
P.S. Today's update to the Poison Master series, this is the 3rd article.