M. balfouri Capstone summary

Sarkhan42

Arachnoangel
Joined
Dec 29, 2015
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901
Its finally time that I'm able to post a summary for my undergraduate capstone project! I've officially graduated, completed a paper, and presented this experiment before the professors in my department. I'm going to try to keep this summary brief and digestible, so if I miss anything please ask about it and I can let you know if I have an answer!(I'm also unsure if I'm actually allowed to post my paper yet so avoiding that for now)

A disclaimer: this project is FAR from perfect, and in many cases for the conclusions I'd like to have much larger sample sizes. This is also not an officially published study, there are plenty of errors that could be corrected, but it is my honest first attempt at a true scientific experiment on this wonderful species and I hope you enjoy some of my observations and takeaways nonetheless.

If you'd like a TLDR on the conclusions, I'll leave one at the bottom ;)

For those of you who may not know- for my undergraduate "capstone" project, I performed a study comparing growth and behavior in communal and solitary M. balfouri. The idea was to procure some stronger data to support or refute common claims about communal tendencies in the hobby.

I began this experiment with 49 healthy spiderlings from the same sack. I set up 7 communals of 5, and 14 individuals. Substrate, enclosure volume, and hides were all standardized by spider(aka the communal had 5x the quantity.). Food, temperature, and humidity were also all kept standard, with the food scaling up as they grew. In ALL variable cases I attempted to remove any limiting factors wherever possible, ex copious food and territory space.

I recorded DLS every 60 days (they grew FAR slower than I had experienced with my past communal, unfortunately) including when they were received, up to 180 days. I recorded activity every ~3 days. For clarity, activity was deemed as any surface activity performed within the window of time that they were all observed. I also separately recorded communal specific behaviors. I also recorded sex among the solitary individuals in order to determine if it played a role in behavior and growth

Growth showed no significant differences between communal and solitary living spiders. The only interesting thing procured here was that in the 3 communal groups that lost a member(singular member, notably) in every case it was the runt among them that was lost, and in 2/3 cases the body was actually recovered with no signs of cannibalism. I suspect some degree of competition is still responsible for many of the deaths we observe, despite copious food or other resources.

Behavior however, was significantly skewed towards solitary living individuals, and I've included the graph as a visual. You can also see a massive amount of variation within the solitary individuals. Purely speculating, I suspect this might be due to restless seeking in solitary slings given the communal behaviors I observed.


Sex was also found to have no impact on growth or behavior in the solitary individuals.

Finally as far as communal behaviors observed- generally I observed your standard balfouri behaviors. Prey sharing, burrow sharing, shared burrow building, following behavior, and general tolerance despite defensiveness towards yours truly, etc.

However, what I did observed that was extremely interesting was that on introduction to a new space, communal individuals would spread out and found very basic burrows for themselves independently. As time went on during the first week, they would slowly but surely abandon these burrows in favor of living with the group in a specific corner of the enclosure. To be clear, they used up only a tiny space of the much larger enclosure as a group, rather than choosing territory independently, which I found extremely interesting.

Finally as I posted in another thread- moisture is almost certainly a very potent molting trigger for these spiders, having almost a dozen individuals molting only 45 minutes after moisture levels were raised significantly.

TLDR:
Solitary vs communal has no impact on growth, but solitary individuals showed higher activity levels. Individuals were found to preferentially group together over dispersing in a greater area. Sex had no influence on either variable.
 

chanda

Arachnoking
Old Timer
Joined
Jun 27, 2010
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2,229
However, what I did observed that was extremely interesting was that on introduction to a new space, communal individuals would spread out and found very basic burrows for themselves independently. As time went on during the first week, they would slowly but surely abandon these burrows in favor of living with the group in a specific corner of the enclosure. To be clear, they used up only a tiny space of the much larger enclosure as a group, rather than choosing territory independently, which I found extremely interesting.
I'm just curious - when you introduced the communal spiders to a new space, did you provide any sort of starter burrows for them, or set them out on "virgin" substrate with no pre-made holes or depressions? Was there any cover present in the new enclosure - such as cork slabs or hides - and if so, did they burrow in proximity to the cover? I just ask because I have not noticed my own balfouri communal attempting to disperse initially following a rehouse before shifting back to communal living - but I did always provide a starter burrow, usually under a hide or slab of cork. Perhaps the attempts to establish independent burrows might be caused by the lack of already available burrows, but once one of them establishes a suitable space, they all move to occupy it?

An interesting study! Thank you for sharing!
 

Sarkhan42

Arachnoangel
Joined
Dec 29, 2015
Messages
901
I'm just curious - when you introduced the communal spiders to a new space, did you provide any sort of starter burrows for them, or set them out on "virgin" substrate with no pre-made holes or depressions? Was there any cover present in the new enclosure - such as cork slabs or hides - and if so, did they burrow in proximity to the cover? I just ask because I have not noticed my own balfouri communal attempting to disperse initially following a rehouse before shifting back to communal living - but I did always provide a starter burrow, usually under a hide or slab of cork. Perhaps the attempts to establish independent burrows might be caused by the lack of already available burrows, but once one of them establishes a suitable space, they all move to occupy it?

An interesting study! Thank you for sharing!
I provided them with a hide per spider, which were halved small plastic cups that I had previously used as sling hides, but did not attempt to set up any starter burrows. They went about creating their own burrows, silk and all, prior to reconvening, so it wasn't simply them not finding anywhere to set up shop so to speak as far as I'm aware. They also did not necessarily use the hides I provided. While some gladly used the space webbing them up heavily, in many cases they just took the anchor points that they saw fit to develop their network of an almost dirt carpet of tunnels sunk into the soil.
 
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