What makes a female black widow so poisonous;not to mention aggressive, as compared to other spiders???

Question

Thanks for your answer...Tom Science 4

Answer 1

Its not necessarily extra poisonous or aggressive.

The problem is the fact that they come in contact with humans more often than most other dangerous spiders. They are no more aggressive, the average person gets about 10 spider bites a year but because they are from less poisonous spiders they can go unnoticed.

The reason why it is so poisonous is because it simply has a very concentrated and effective poison. It just happens to be that way. It's similar to poisonous snakes and jellyfish, some are simply just more poisonous.

The thing that makes black widow venom so dangerous is because unlike most venom's which carry 1 or 2 active agents, black widows carry about 5 types that when combined makes it more effective.

The make up of black widow venom is:
1) Latrotoxins (five insecticidal toxins, termed α, β, γ, δ and ε-latroinsectotoxins, one vertebrate-specific neurotoxin, α-latrotoxin, and one toxin affecting crustaceans, α-latrocrustatoxin)
2) Adenosine (causes transient heart block in the AV node. It also causes endothelial dependent relaxation of smooth muscle as is found inside the artery walls. Aka - stops your circulatory system.)
3) Guanosine
4) Inosine
5) 2,4,6-trihydroxypurine

3,4 and 5 interfere with DNA replication and other cell processes which is what cause the longterm dammage.

Answer 2

The Black Widow spider is NOT known to be aggressive so that its wrong. They dont even live in houses because they are shy.

The black widow lives in undisturbed locations under trash, litter, boards and rocks. Little-used buildings may be infested as well as crawl spaces, cellars and basements. These spiders construct an irregular web in spaces between objects. They typically do not leave the web. Female black widow spiders are shy and nocturnal. Bites usually occur when humans come into direct contact with the web or when the spider is unknowingly pinned against their skin.
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The Venom
Although almost all spider species possess poison only a few species produce a venom virulent to be harmful to humans. Black widows are very timid spiders and are not known to agressively bite humans. However, the venom of black widows is a neurotoxin and it may interfere with the nerve impulses to muscle tissue. After being biten from a black widow one may feel painful rigidity in the muscles of the abdomen and a feeling of tightness in the chest. Other symptoms include an increase in blood pressure, a rise in body temperature, nausea, and sweating. Death is uncommon (less than 1% of the reported cases), but in the elderly or very young death may occur from asphyxia 14-32 hours after being bitten. Seek medical attention if you suspect you have been bitten. Without medical attention the symptoms can last 5 days and a complete recovery may take weeks.

Answer 3

I know that in snakes, a lot of the especially neurotoxic species happen to eat other reptiles. And I think it was Terry Irwin on the Croc Hunter who once said that it takes a stronger nerve poison to immobilize reptile prey because they're metabolisms are slow. I wonder if something similar applies to toxic spiders; that it's what they need to defend themselves from their most common enemies, or immobilize their most common food.