- Joined
- Jul 7, 2005
- Messages
- 3,200
I've been looking for datasets to analyze in order to practice my R programming, and a friend of mine suggested I analyze bite reports to figure out what activities are most risky to the keeper because they're interested in keeping Poecilotheria metallica. They're a new keeper, so I strongly discouraged them from doing this...but they wanted to see the analysis and I figured it would generate some discussion here.
So I read through all of the bite reports here on Arachnoboards (N=171), mainly to figure out what activities people were performing at the time they got bitten. I wanted to stick to one website to minimize the chance of double-reporting, but also because AB gave me enough data to allow me to differentiate between OW (N=68) and NW (N=103) tarantulas. I analyzed this for both centipedes and tarantulas, but I'm only presenting tarantulas here for the time being. I do plan on performing the centipede analysis, and presenting it in the Myriapod forum, but want to see what T keepers think before I do that. Given the severity of centipede bites, I felt that I should get in some peer-review before I replicated the analysis for that group.
The number of bite reports varied wildly, but no species (or even genus) had gathered a number of bite reports which would allow me to do a meaningful comparison for genus or even species. So I split tarantulas into two categories: Old World and New World. I discarded any report which did not list the activity at the time of the bite, I discarded any reports from wild specimens, or specimens which had escaped for a prolonged period of time. I initially counted breeding as a category, but ended up discarding those posts because there weren't enough to analyze (e.g. they screwed up my chi-squared analysis due to small sample size).
My definitions are as follows:
OW: Tarantulas from Europe, Asia, Australia, Africa
NW: Tarantulas from North or South America, including the Caribbean
Maintenance: Removal of excess food, removal of waste, rearrangement of habitat, packing for temporary housing (e.g. substrate change, vacation, shipping/receiving, etc), adding water to water dish, adding water to substrate.
Feeding: Introduction of food. This includes tong feeding, hand-feeding, and dropping food directly onto the substrate.
Breeding: Removal of specimen for purposes of introducing to specimen of opposite sex, or removal of specimen post-mating
Handling: Removal of specimen from container for nonessential purposes. There are some maintenance posts which I considered handling, but they're relatively rare, and we can discuss this in the comments if people think this is a problem. There are also instances of induced bites which I considered handling (because induced bites are nonessential), but these are also relatively rare. I'm not sure that either of these would change my analysis.
So, with all of that in mind, here is the figure I came up with for this study:
This, by the way, is statistically significant:
People who own NW tarantulas tend to get bit during handling, and people who own OW tarantulas tend to get bitten during maintenance. Many of the bite reports for OW species mentioned (or strongly implied) that no tools (e.g. tongs) were used during maintenance. However, one or two posts did explicitly mention using tongs, appropriate (e.g. puncture-proof) gloves, or catch-cups. Although I didn't analyze this because the number was too low to achieve statistical significance, I suspect tongs and similar tools (e.g. gloves) do have a protective effect. The reason we don't see tools mentioned in bite reports is almost certainly survivorship bias. Or, in other words:
If you know, you know. If not, here's context for the picture.
All in all, I'm not convinced that bite reports actually tell us much. I think that they can tell us that a bite from, say, Poecilotheria is more problematic than a bite from, say Brachypelma. I didn't do that analysis, but if I were to rate it on a scale of 1-5, all the Brachypelma bite reports are a 1 and all the Poecilotheria bite reports are a 5. I'd be willing to do the analysis if there's enough interest, but from what I read, the OW/NW divide seems fine statistically. I'm not convinced there's enough data to group the severity of Psalmopoeus and Iridopelma bites into NW or OW categories.
Obviously, if you're handling, you're at greater risk for a bite because there's prolonged contact in an unfamiliar environment. There was not enough data for me to differentiate when the bite took place. I suspect that most bites took place during the introduction phase, however; the keeper was bitten when they put their hand in front of the spider for the first time that day. I would have liked to do that analysis, but there is not enough data for me to statistically analyze because the reports are not in-depth enough for me to make that call. We need greater standardization for bite reports.
We should not interpret this data to imply that handling of NW species is risker than handling of OW species for a few reasons. First, handling is probably more common in NW species because of their docile reputation. Bites are more rare, and therefore, more noteable. In other words, they're more likely to get reported because they're weird. I'd imagine that fewer people keep OW species, and those who keep OW species are more likely to take precautions...and are also more likely to report because a bite is more notable for them. Not only because of the novelty (experienced keepers don't get bit that much), but because of the severity.
Finally, I want to talk a little bit about risk analysis. There's some mathematics to getting bit. Pternochilus (e.g. OBT) is more likely to tag you than a Poecilotheria, but the consequences of getting tagged by a Poecilotheria is greater than a OBT. Both bites aren't fun to deal with, but I'd rather take the risk of sticking my hand into a P. metallica enclosure than a P. murinus enclosure. The venom from P. metallica is clearly worse, but it's more likely to hide than P. murinus. Having kept both, I'd rate P. metallica at a Score 3-4, and a P. murinus at Score 8-9 based on the scale presented below:
Overall, I'm interested to see what people think. I'm willing to send my R analysis and data to anyone who wishes to replicate my work.
So I read through all of the bite reports here on Arachnoboards (N=171), mainly to figure out what activities people were performing at the time they got bitten. I wanted to stick to one website to minimize the chance of double-reporting, but also because AB gave me enough data to allow me to differentiate between OW (N=68) and NW (N=103) tarantulas. I analyzed this for both centipedes and tarantulas, but I'm only presenting tarantulas here for the time being. I do plan on performing the centipede analysis, and presenting it in the Myriapod forum, but want to see what T keepers think before I do that. Given the severity of centipede bites, I felt that I should get in some peer-review before I replicated the analysis for that group.
The number of bite reports varied wildly, but no species (or even genus) had gathered a number of bite reports which would allow me to do a meaningful comparison for genus or even species. So I split tarantulas into two categories: Old World and New World. I discarded any report which did not list the activity at the time of the bite, I discarded any reports from wild specimens, or specimens which had escaped for a prolonged period of time. I initially counted breeding as a category, but ended up discarding those posts because there weren't enough to analyze (e.g. they screwed up my chi-squared analysis due to small sample size).
My definitions are as follows:
OW: Tarantulas from Europe, Asia, Australia, Africa
NW: Tarantulas from North or South America, including the Caribbean
Maintenance: Removal of excess food, removal of waste, rearrangement of habitat, packing for temporary housing (e.g. substrate change, vacation, shipping/receiving, etc), adding water to water dish, adding water to substrate.
Feeding: Introduction of food. This includes tong feeding, hand-feeding, and dropping food directly onto the substrate.
Breeding: Removal of specimen for purposes of introducing to specimen of opposite sex, or removal of specimen post-mating
Handling: Removal of specimen from container for nonessential purposes. There are some maintenance posts which I considered handling, but they're relatively rare, and we can discuss this in the comments if people think this is a problem. There are also instances of induced bites which I considered handling (because induced bites are nonessential), but these are also relatively rare. I'm not sure that either of these would change my analysis.
So, with all of that in mind, here is the figure I came up with for this study:
This, by the way, is statistically significant:
People who own NW tarantulas tend to get bit during handling, and people who own OW tarantulas tend to get bitten during maintenance. Many of the bite reports for OW species mentioned (or strongly implied) that no tools (e.g. tongs) were used during maintenance. However, one or two posts did explicitly mention using tongs, appropriate (e.g. puncture-proof) gloves, or catch-cups. Although I didn't analyze this because the number was too low to achieve statistical significance, I suspect tongs and similar tools (e.g. gloves) do have a protective effect. The reason we don't see tools mentioned in bite reports is almost certainly survivorship bias. Or, in other words:
If you know, you know. If not, here's context for the picture.
All in all, I'm not convinced that bite reports actually tell us much. I think that they can tell us that a bite from, say, Poecilotheria is more problematic than a bite from, say Brachypelma. I didn't do that analysis, but if I were to rate it on a scale of 1-5, all the Brachypelma bite reports are a 1 and all the Poecilotheria bite reports are a 5. I'd be willing to do the analysis if there's enough interest, but from what I read, the OW/NW divide seems fine statistically. I'm not convinced there's enough data to group the severity of Psalmopoeus and Iridopelma bites into NW or OW categories.
Obviously, if you're handling, you're at greater risk for a bite because there's prolonged contact in an unfamiliar environment. There was not enough data for me to differentiate when the bite took place. I suspect that most bites took place during the introduction phase, however; the keeper was bitten when they put their hand in front of the spider for the first time that day. I would have liked to do that analysis, but there is not enough data for me to statistically analyze because the reports are not in-depth enough for me to make that call. We need greater standardization for bite reports.
We should not interpret this data to imply that handling of NW species is risker than handling of OW species for a few reasons. First, handling is probably more common in NW species because of their docile reputation. Bites are more rare, and therefore, more noteable. In other words, they're more likely to get reported because they're weird. I'd imagine that fewer people keep OW species, and those who keep OW species are more likely to take precautions...and are also more likely to report because a bite is more notable for them. Not only because of the novelty (experienced keepers don't get bit that much), but because of the severity.
Finally, I want to talk a little bit about risk analysis. There's some mathematics to getting bit. Pternochilus (e.g. OBT) is more likely to tag you than a Poecilotheria, but the consequences of getting tagged by a Poecilotheria is greater than a OBT. Both bites aren't fun to deal with, but I'd rather take the risk of sticking my hand into a P. metallica enclosure than a P. murinus enclosure. The venom from P. metallica is clearly worse, but it's more likely to hide than P. murinus. Having kept both, I'd rate P. metallica at a Score 3-4, and a P. murinus at Score 8-9 based on the scale presented below:
Overall, I'm interested to see what people think. I'm willing to send my R analysis and data to anyone who wishes to replicate my work.
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made me remember when I had to code a bunch of horrible lotka Volterra and population trend equations in population dynamics for chipmunks, that was a surpressed memory 
