Brown Recluse spiders

[fishman10]

I took these photographs of a brown recluse spider up close. We find these everywhere in our house in North Texas. Not a spider you want to get bit by. Its not really fatal, few if anyone dies from a bite, but the bite does rot the flesh away and will leave lots of bad memories.

http://www.gather.com/viewSlideshow.action?albumId=34211

 

[oldmanofthesea]

Great pictures! Ron

 

[Anonymity82]

Very nice pictures! I love how people in my area, NC, are always complaining about how many brown recluse they see. I try to explain that this is not their habitat and unless you look at them closely they look a lot like other spiders but they don't listen to me... Maybe I will show them these pics and tell them to get a good look next time.

Also, the rumors of death kills me sometimes! To the non keeper or hobbyist, brown recluse and black widows are lethal. They can kill you in a short period of time etc... Again, I explain and they nod and go off and tell other people the same parroted garbage they tried to tell me.

Anyhow, really nice photos! I will definitely show these the next time someone tries to tell me they found a large "nest" of brown recluse.

 

[Ciphor]

Dermal necrosis is only observed in about 1 in 20 cases. It is not a consistent symptom, as not all recluse spiders carry the pathogen that leads to necrosis.

 

[tarantulito]

Dermal necrosis is only observed in about 1 in 20 cases. It is not a consistent symptom, as not all recluse spiders carry the pathogen that leads to necrosis.

the necrosis is caused by sphingomyelinase D in the venom.

http://www.ncbi.nlm.nih.gov/pubmed/15777950

 

[Ciphor]

Yes that's right, not a pathogen sorry. Like a pathogen. But still dermal necrosis is only observed in about 1 in 20 confirmed bites.

 

[Venom]

Your stat of 1 in 20 bites causing necrosis may serve as a generalization, (though could we have a citation?) but I don't think it should prompt us to say that necrosis is not a consistent symptom. Sphingomyelinase-D is always cytotoxic--that doesn't vary. It's chemical action remains the same in every bite. What varies is venom yield, AND, the other un-sung factor of Loxosceles bites: the location of the bite. This second factor is critically important in determining the overall severity, because the SMD enzyme works especially well in fatty tissues (it's called sphingomyelinASE because it breaks down sphingomyelin, which is a lipid component of the cell membrane). Thus, WHERE one is bitten actually changes the efficacy of the venom in affecting one's tissues. Thighs, bellies, buttocks and other generally adipose-rich areas are much more susceptible to serious necrosis than are the backs of hands or elbows. Now, maybe 1 in 20 bites, on average, gets the right combination of location and dosage, but I think we need to be careful not to imply that Loxosceles bites inherently aren't serious--they are. It's simply that it's a matter of Russian roulette as to what exactly results from a bite.

By the way, 1 in 20 is the rate of death from untreated Latrodectus envenomation, when averaged across the entire age/health demographic spectrum. I think we'd agree that's a significant stat.

 

[tarantulito]

Yes that's right, not a pathogen sorry. Like a pathogen. But still dermal necrosis is only observed in about 1 in 20 confirmed bites.

I don't doubt that's true; but would you happen to have a reference for this?
Thanks.

While living in Oklahoma I was once bitten by what I was convinced was a brown recluse, my only evidence being that my house was crawling with them. Whatever it was, left a big goose-egg on my shin that was red and itchy but disappeared in a couple of days.

edit- woops, venom beat me to it.

 

[Ciphor]

Your stat of 1 in 20 bites causing necrosis may serve as a generalization, (though could we have a citation?) but I don't think it should prompt us to say that necrosis is not a consistent symptom. Sphingomyelinase-D is always cytotoxic--that doesn't vary. It's chemical action remains the same in every bite. What varies is venom yield, AND, the other un-sung factor of Loxosceles bites: the location of the bite. This second factor is critically important in determining the overall severity, because the SMD enzyme works especially well in fatty tissues (it's called sphingomyelinASE because it breaks down sphingomyelin, which is a lipid component of the cell membrane). Thus, WHERE one is bitten actually changes the efficacy of the venom in affecting one's tissues. Thighs, bellies, buttocks and other generally adipose-rich areas are much more susceptible to serious necrosis than are the backs of hands or elbows. Now, maybe 1 in 20 bites, on average, gets the right combination of location and dosage, but I think we need to be careful not to imply that Loxosceles bites inherently aren't serious--they are. It's simply that it's a matter of Russian roulette as to what exactly results from a bite.

By the way, 1 in 20 is the rate of death from untreated Latrodectus envenomation, when averaged across the entire age/health demographic spectrum. I think we'd agree that's a significant stat.

Good info, 1 in 20 is what I hear in passing conversation between circles of entomologist I talk with on a regular basis. I remember reading something about it from Rick.

Maybe these citations that show how uncommon necrosis is in Loxosceles reclusa bites? "The most common symptoms were pain, pruritus, malaise, chills, sweats, and rash."

http://www.ncbi.nlm.nih.gov/pubmed/3631681 Or this one? "Most brown recluse spider bites are asymptomatic"

Most severe bites result in similar damage to this image.

EDIT TO ADD: Btw I'm in no way saying this is not a spider to be cautious of, it very much is, and it definitely lives up to its name. Just trying to keep things factual. If you got something that shows necrosis is common in bites, I'd love to read it!

 

[The Snark]

Let's reign this one in a little, okay?

-Lox R 'almost but missed' bites aren't recorded and no scientific data is possible.
-Actual Lox R proven bites that did not envenom is still conjecture. We have all seen how the public from high skool undergraduates to medical doctors regularly blame everything from saddle burr punctures to whaling harpoon jabs on Lox.
-Many reported Lox bites that produce symptoms similar to that of Lox did not accurately identify the spider.

Lox bites where the spider was positively identified but did not result in actual classic necrosis gets buried under the aforementioned noise. I think we can safely say we are trying to juggle numbers accurately when much of the data we have to work with is erroneous or incomplete. Is there even an accurate record where a competent arachnologist positively identified the spider as a Lox R and observed the necrotic manifestations, or lack of, in conjunction with a trained medical specialist?

From what I am seeing, it could easily be that every Lox R bite that delivered venom produced some necrosis. It could just as easily be that thousands of Lox R bites failed to deliver an effective venom load and many of those weren't even noticed and reported.

 

[Venom]

Just some interesting material for further reading.


This is a database, apparently contributed to by physicians documenting L. reclusa cases they have treated:

http://dermatlas.med.jhmi.edu/derm/result.cfm?Diagnosis=-1728119193


If you scroll almost all the way down this page, you'll find graphical representations of the toxin sphingomyelinase. It's a whopper of a complex molecule!

http://www.jbc.org/content/early/2005/01/14/jbc.M412437200.full.pdf

And this article, probably well-known here now, says the following:

"A panoramic sight of epidemiological, clinical and experimental studies, referring to Loxosceles laeta and loxoscelism, carried out in 1955-1988, in Santiago, Chile is presented. Two-hundred and sixteen cases of loxoscelism were studied. The most relevant features were: 84.3% corresponded to cutaneous loxoscelism (CL) and 15.7% to viscerocutaneous loxoscelism (VCL)"

--from: http://www.ncbi.nlm.nih.gov/pubmed/2577020

Granted, they were dealing with L. laeta, L. gaucho and L. intermedia (all of which are larger and more toxic than L. reclusa), but it establishes a strong link to dermonecrosis from SMD toxicity in Loxoscelid spiders. L. laeta in specific has about 10x more concentrated venom than L. reclusa, ( as per this study: http://www.lclark.edu/~binford/SMDDistribution copy.pdf ), so it might be reasonable to extrapolate that, per the average wet bite, we could expect from L. reclusa about 1/10th the incidence of cutaneous loxoscelism that L. laeta induces, which would be an 8.4% incidence (1 in 11.9). The only variable, then, would be whether L. reclusa chooses to inject venom more, or less frequently than L. laeta, which I'm not sure how to deduce. The method used to determine the relative concentration of L.reclusa versus L. laeta venom was electrostimulation milking, rather than just pressing the spider to a membrane and letting it bite without stimulation. I'm not sure if that makes any difference, but I think it would be a good study, to find what the relative abundance of actual wet bites is in L. reclusa.

 

[The Snark]

Venom, that is one exceptionally lucid well written post.

I note your italics on the word 'might' (be reasonable... ) That's one big potential leak in that hypothesis bucket. Have you reached any conclusions in this regard? Wild guesses? Educated opinions?

Statistics. Please see http://www.arachnoboards.com/ab/showthread.php?232232-Bite-Reports&p=2042208#post2042208

 

[Ciphor]

Its good information, thanks Venom.

I will add tho, I personally think drawing a connection between two different species is moot, even if they are in the same genera. Point and case, compare Latrodectus hasselti bite/deathratio/etc. with L. geometricus. Both in same genus, both have same proteins in their venom, but two completely different outcomes with their bites. I think another issue with studies like these is that they are only studying cases that get brought to their attention, which are generally more sever. If you are working with 200 cases of bites that got reported, how many cases did not get reported where the symptoms were not bad enough to report? How many people got bit and had a medium bad reaction and simply rod it out at home?

I reached out to rick about the ratio of dermonecrosis he believes occurs in bites from this spider. Hopefully I get a decent turn around on his reply.

 

[Toogledoo]

Thos are some good pictures fishman. We live in SW Kansas and we have them everywhere here as well! We recently caught one in the bathtub, our cat brought one in on his fur, and just this morning I washed my hands and felt something in the towel get on my hand when I dried them and a brown recluse dropped out onto the floor... Scared the crap out of me! :S

 

[Galapoheros]

Great pics, thanks. It's amazing how fast the venom subdues prey. I have these all over my house, I keep them in a deli now and then to watch them. They lunge, bite, back up, wait to eat. I have a Centruroides vittatus problem in the house also. I thought the vittatus would catch and eat recluse spiders with no problem but the recluse killed the scorpions both times that I tried it. Amazing little spiders even though they didn't make it either.

I want to add that these aren't really social spiders. There was a recent thread with a post stating they were social, after somebody observed several in a jar in a home. They fall in and can't get out, but they are social enough, ...or weary enough to avoid each other. I've had it happen several times over here in delis and bowls. They would make more distance if they could in those circumstances, imo, but the cases are that they don't know how to get out of the containers, going by my observations anyway.

 

[loxoscelesfear]

I want to add that these aren't really social spiders. There was a recent thread with a post stating they were social, after somebody observed several in a jar in a home. They fall in and can't get out, but they are social enough, ...or weary enough to avoid each other. I've had it happen several times over here in delis and bowls. They would make more distance if they could in those circumstances, imo, but the cases are that they don't know how to get out of the containers, going by my observations anyway.

Maybe not sociable. They do tolerate one another. I have found half a dozen under the same rock. They will eat each other if tossed in containers together, but at the same time several can be kept in a small container if you provide an empty TP roll. Recluse does not seem to apply to their true life style. Where there is one, many more are nearby. This spring I was lucky enough to observe reclusa in the act of eating prey: one had a Phidippus audax in its jaws when I turned over a rock. The other was eating a large May beetle on the side of a barn. Both these prey items dwarfed the spiders themselves.

 

[Ciphor]

I want to add that these aren't really social spiders. There was a recent thread with a post stating they were social, after somebody observed several in a jar in a home.

That was me, and I never "stated" they were social.
http://www.arachnoboards.com/ab/showthread.php?231649-Giant-T.-Gigantea&p=2040756#post2040756

Yup brown recluse are definitely fully communal. I've seen them in a pile on the bottom of a jar. If they are fed, they don't care.

in science, and more importantly Biology, we draw a definite distinction between "Social" behavior and "Communal" behavior. Loxosceles reclusa is communal, and are not social.

The two words communal and social do have similarities, but they are not the same.

In terms of biology these words to me mean
Social: living or disposed to live in companionship with others or in a community, rather than in isolation: People are social beings.
Communal: Shared by all members of a community; for common use. Not to be confused with a community. A street for example is communal, no one would say they are being social driving on the freeway.

So, they are communal in that they share a common space without killing each other. They are not social in that they do not seek this out, it is a tolerated understanding that they must share the same space to be successful as a species.

For further clarification, in biology we also use a term "Sub-communal" Which means, they will have some spaces that are shared, but never without tension, and they will always have their own space that is not shared.

 

[khaos]

I had no idea that different spiders may carry different pathogens. It totally makes sense, but information that the paranoid public probably won't listen to, unfortunately. This thread is very informative. Thanks to all who are sharing their extensive knowledge of this misunderstood species.