# Black widow spider & evolution



## enlightenment (Dec 14, 2006)

The *black widow spider* is a group of spiders which includes the *southern black widow* (_Latrodectus mactans_), the *northern black widow* (_Latrodectus variolus_), and the *western black widow* (_Latrodectus hesperus_). They are well known for the distinctive black and red coloring of the female of the species and for the fact that she will occasionally eat her mate after reproduction. Members of the three species are often confused with the False Black Widows.

Black widow spiders typically prey on a variety of insects, but occasionally they do feed on*woodlice**, **diplopods**, **chilopods* and other*arachnids*. When the prey is entangled by the web, _L. mactans_ quickly comes out of its retreat, wraps the prey securely in its strong web, then bites and envenoms its prey. *The venom takes about ten minutes to take effect;* in the meantime, the prey is held tightly by the spider. When movements of the prey cease, digestive enzymes are released into the wound. The black widow spider then carries its prey back to its retreat before feeding





Although these spiders are not especially large,* their venom is extremely potent *(it is also reported to be much more potent than the venom of cobras and coral snakes). Compared to many other species of spiders, their chelicerae are not very large or powerful. In the case of a mature female, the hollow, needle shaped part of each chelicera, the part that penetrates the skin, is approximately 1.0 millimeters (about .04 in) long, long enough to inject the venom to a point where it can be harmful. The males, being much smaller, inject far less venom with smaller chelicerae. The actual amount injected, even by a mature female, is very small in physical volume. When this small amount of venom is diffused throughout the body of a healthy, mature human, it usually does not amount to a fatal dose (though it can produce the very unpleasant symptoms of latrodectism). Deaths in healthy adults from _Latrodectus_ bites are relatively rare in terms of the number of bites per thousand people. Sixty-three deaths were reported in the United States between 1950 and 1959[17]. On the other hand, the geographical range of the widow spiders is very great. As a result, far more people are exposed, worldwide, to widow bites than to bites of more dangerous spiders, so* the highest number of deaths worldwide are caused by members of their genus.* Widow spiders have more potent venom than most spiders, and prior to the development of antivenin, 5%of reported bites resulted in fatalities. The venom can cause a swelling up to 15 cm. Improvements in plumbing have greatly reduced the incidence of bites and fatalities in areas where outdoor privies have been replaced by flush toilets.
There are a number of active components in the venom:



Two things.

In evolutionary terms, what possible benefit is it for a spider that is so small, and each such small prey to be quite this venomous? You can cite 'defence', and that is fair enough, yet no other small spider like this evolved to have venom that strong.

Also, ten mins for the venom to kick in re it's prey?

I would have thought if it were that strong, it would be more like seconds?


----------



## joeyboy (Jul 19, 2008)

Surely sometimes it isn't that they needed powerful venom it's more mammals happen to be susceptible to the chemicals in their type of venom. It may be other animals are not so badly effected.


----------



## enlightenment (Dec 14, 2006)

joeyboy said:


> Surely sometimes it isn't that they needed powerful venom it's more mammals happen to be susceptible to the chemicals in their type of venom. It may be other animals are not so badly effected.


Possibly.

But as spiders go, the fact remains that it is 

A) Very small

B) Very venmous (when compared to all other spiders)

I was just making the point that it is unique as spiders go, for that one aspect.

: victory:


----------



## ph0bia (Feb 21, 2009)

enlightenment said:


> Possibly.
> 
> But as spiders go, the fact remains that it is
> 
> ...


No it's not. It's not unique in that at all, and it is not "Very venomous". It just so happens that the venom is potent to humans. It's the same way that a mouse might refer to utricating bristles as 'lethal', when they're not to humans.

The chemical composition of Black Widow venom just happens to contain chemicals that make it more_ potent_ than some others. As for defense, no, it's an attack venom.

Before people argue with this, I do have experience here. I have held a Black Widow and I have seen one sitting upon her egg sack be poked by a human index finger quite brutally. The spider refuses to bite.

Nearly every single recorded case of a confirmed BW bite was bitten either on the foot when someone attempted to put on a shoe that was inhabited by a BW, or beneath clothing where the BW was trapped. The remainder have nearly all been attributed to the idiot trying to squash the spider.

Only if they have absolutely nowhere to run, they bite. It is therefore not a defense mechanism.

When they say it takes 10 mins to take effect, they mean 10 mins to utterly kill the prey and turn the insides to soup. Contrary to popular media, very few venoms are potent enough to kill anything in a matter of seconds (alone) especially in the small doses the BW injects.

This is the sad thing of media presentation... we see people in movies die of venom in seconds... A mouse wouldn't, so a human won't. To die of BW bites (which in itself isn extremely rare now the AV has been produced) takes a long time for a human.

Don't trust all you copy from Wikipedia.


----------



## enlightenment (Dec 14, 2006)

ph0bia said:


> No it's not. It's not unique in that at all, and it is not "Very venomous". It just so happens that the venom is potent to humans. It's the same way that a mouse might refer to utricating bristles as 'lethal', when they're not to humans.
> 
> The chemical composition of Black Widow venom just happens to contain chemicals that make it more_ potent_ than some others. As for defense, no, it's an attack venom.
> 
> ...


Ouch.

That stung a bit, for the first post I read today!

:Na_Na_Na_Na:


----------



## shiffty (Mar 21, 2009)

Hello
I'm new to the site, i've signed up because i've always been intrested in animals and have kept loads of different things over the years. At the moment i'm big into fish keeping, but after a recent trip to australia i got home to find a austalian female red back (black widow) spider in my luggage:gasp: I wasn't sure what to do with it! but i've put it in a spare viv i had and have been feeding it for the last few weeks. It seems to be doing just fine and is great to watch, has anyone got any advice for me?????

I already know not to get bitten by it:lol2:


----------



## andy2086 (Dec 26, 2008)

shiffty said:


> Hello
> I'm new to the site, i've signed up because i've always been intrested in animals and have kept loads of different things over the years. At the moment i'm big into fish keeping, but after a recent trip to australia i got home to find a austalian female red back (black widow) spider in my luggage:gasp: I wasn't sure what to do with it! but i've put it in a spare viv i had and have been feeding it for the last few weeks. It seems to be doing just fine and is great to watch, has anyone got any advice for me?????
> 
> I already know not to get bitten by it:lol2:


I'd ask the environmental health department of your local council of anyone in your area who's got a dangerous wild animal licence because you need one to keep a black widow. If found you could be fined quite a lot of money if you don't have a licence! I'm sure they'd understand that it was in your luggage though.
That or just keep quiet about it & hope no one finds out, the choice is yours mate


----------



## enlightenment (Dec 14, 2006)

Oh, this thread has re-appreared!

Talking of Black Widows, I watch this (fairly poor) programme on a Sunday night - *Verminators.*

Essentially a programme about a company who tackle people that have an infestation of mice, rats, etc.

Usual stuff.

Last week, the feature was an American lady who had stables.

She had black widows all over the place.

Fella turns over a wheelbarrow, and there was like a 'colony' of them there, all different ages. Didn't think they lived in that manner, thought they were *strictly *solitary.

Shame he used chemicals to eradicate them.

Perhaps there could have been another method?


----------



## enlightenment (Dec 14, 2006)

shiffty said:


> Hello
> I'm new to the site, i've signed up because i've always been intrested in animals and have kept loads of different things over the years. At the moment i'm big into fish keeping, but after a recent trip to australia i got home to find a austalian female red back (black widow) spider in my luggage:gasp: I wasn't sure what to do with it! but i've put it in a spare viv i had and have been feeding it for the last few weeks. It seems to be doing just fine and is great to watch, *has anyone got any advice for me?????*
> 
> I already know not to get bitten by it:lol2:


Yes.

_Don't_ announce it on the internet!

:whistling2:


----------



## Ozgi (Jun 1, 2008)

shiffty said:


> Hello
> I'm new to the site, i've signed up because i've always been intrested in animals and have kept loads of different things over the years. At the moment i'm big into fish keeping, but after a recent trip to australia i got home to find a austalian female red back (black widow) spider in my luggage:gasp: I wasn't sure what to do with it! but i've put it in a spare viv i had and have been feeding it for the last few weeks. It seems to be doing just fine and is great to watch, has anyone got any advice for me?????
> 
> I already know not to get bitten by it:lol2:


 Lol! Make sure it doesn't escape!


----------



## ph0bia (Feb 21, 2009)

Are we even certain it's a Black Widow and not a Steatoda species?? I'm surprised none have suggested this yet, especially as the Australian Red-Back is far easier confused with False Widows than the American variety (with the hour glass).

As for colonies, they don't keep to colonies, but some Steatoda do. Once again, the show got it wrong. They were not dealing with true Black Widows. 

As for keeping it, I'd give the following advice:



Get it properly identified ASAP. If it is a real Latrodectus species, then it is a far more delicate situation!
If it is indeed Latrodectus, either find a _DWAL_ holder near you who would take it off your hands or take it to a vet/store that can advise you what to do with it.
I'd recommend double boxing it, if it's not already. ie, put the box it is in inside another, larger box.
I don't want to be a fear monger, so I will also now point out that getting bitten by a Latrodectus is no easy feat. I have even held one.

They only bite if they are trapped and have no alternative (the spider is well aware that you are 10,000 times larger than it). Most people who get bitten have put their foot in a shoe with a BW in it, or gotten it trapped under clothing etc. Don't worry too much about the creature, just ensure it remains contained until identified (and beyond identification of Latrodectus).

The _DWAL_ is there for a reason. For your own safety and for the safety of those around you, do not attempt to keep it if it is a DWA species. Find someone with the license. Last thing you want is it escaping and turning up somewhere unexpected and causing a bite, either to yourself or neighbours.


----------



## enlightenment (Dec 14, 2006)

Tbh, I am surprised that such a small spider has fangs capable of penetrating human skin!


----------



## ph0bia (Feb 21, 2009)

Incredible, isn't it? That said it doesn't need to penetrate far, it's a neurotoxin that just requires nerve endings. Those are in the upper layers of skin.


----------



## enlightenment (Dec 14, 2006)

ph0bia said:


> Incredible, isn't it? .


Yes mate, it is.

Esp since I have picked up species of native spiders that are dozens of times larger, therefore, yet despite their attempts to bite me, they cannot get through my skin.


----------



## Sollytear (Aug 7, 2008)

I would like to put my 2cents in here, something ive always found interesting.
Ts are generally quiet large and have relatively tame (to humans) venom. Their size is one of thier great advantages.
With scorpions, the rule of thumb is be afraid of the ones with small claws. Why? Smaller the claw, the bigger sting they need, and visa versa.

If you try to apply this to a BW the idea falls apart, because the whole arguement becomes mute once you realise the venom is rated high against humans, not their prey. All of this has been discussed.


----------



## enlightenment (Dec 14, 2006)

Sollytear said:


> I would like to put my 2cents in here, something ive always found interesting.
> Ts are generally quiet large and have relatively tame (to humans) venom. Their size is one of thier great advantages.
> *With scorpions, the rule of thumb is be afraid of the ones with small claws. Why? Smaller the claw, the bigger sting they need*, and visa versa.
> 
> If you try to apply this to a BW the idea falls apart, because the whole arguement becomes mute once you realise the venom is rated high against humans, not their prey. All of this has been discussed.


 
Not always so.

I have a delicate species, from Chile.

Weak venom, I am told.

But I take your general point.


----------



## exopet (Apr 20, 2007)

is anyone aware that widows are poisonous as well?

L. mactans (with removed venom glands) can be processed into a poison that is poweful enough to kill a camel (one adult female spider)


----------



## Sollytear (Aug 7, 2008)

Thats interesting  But I do not know how many people would want to eat a widow.


----------



## C_Strike (Feb 20, 2007)

exopet said:


> is anyone aware that widows are poisonous as well?
> 
> L. mactans (with removed venom glands) can be processed into a poison that is poweful enough to kill a camel (one adult female spider)


Are you sure?
So your saying hypotheitcally, if a camel eats a widow spidewr its likely to die? seesms a bit hard to beleive.

ONly thing i can think is purely extracting certain chemicals from the spider whic are already known to be toxic and concentrating them.

Not saying your lying or anything at all. 
just seems unusual to me, would love to see any documentation to back it up? anythign for me to read about this?


----------



## snickers (Aug 15, 2007)

It's interesting that spider venom is so potent against large mammals. Perhaps there is an evolutionary advantage in having large dead mammals nearby. This isn't very far fetched, because a large dead mammal must have a huge variety of small critters busily converting it back into it's constituent bits. small critters = spider food.

bit far fetched though.


----------



## exopet (Apr 20, 2007)

was in a 1993 issue of National geographic, august I think.


----------



## GRB (Jan 24, 2008)

I've never heard of widow spiders being regarded as poisonous for large mammals...I'm dubious.


----------



## ph0bia (Feb 21, 2009)

I think I remember reading this somewhere, and then shortly after having it debunked. It was theorised they were both venomous and poisonous after indiginous peoples had recorded deaths after eating them. Usually turned out they'd either been bitten before eating them, or during eating.

What makes me rather dubious is the idea of removing venom glands. If you were making a potent poison, surely you'd leave the venom in? Two, how difficult must it be to remove venom glands from one!? No offence intended (read my signature) but I do not believe this at all.


----------

