Water Relations - Desert Burrowers

Mark Newton

Arachnobaron
Old Timer
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Mar 9, 2007
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401
This post was intended for my Australian Scorpion Forum and of course the information relates directly to species from Australia. However, you might find some of the science interesting as clearly it may well relate to desert species from other geographic locations.

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For those who might be interested in the science associated with studying and keeping scorpions. At the moment I am trying to ascertain whether or not U armatus is capable of removing water from soil via osmosis as does U yaschenkoi . Below is a graph showing data from 4 days of evaporative water loss from one individual. The scorpion is housed in an open jar with nothing in it, no substrate. You can see that after 4 days the scorpion has lost 13% of its original body weight, which is quite a bit of water, nearly 0.1g. This is occuring at an average RH of 35%. You can see that it wouldnt take long for your scorpion to kick the bucket if left in a drying atmosphere. This is the average atmosphere in my house at present, in summer it gets a lot lower than this.

Also prelim data indicate U armatus does NOT use osmosis to derive water.

Day 1 is the first day in the experiment, hence only 4 days of water loss, not 5. This equates to nearly 1mg or 0.13% body weight lost every hour when exposed to this atmosphere. When the jar was sealed the water loss became exactly zero inside the next 24 hours. Soil at 1.8% water content was also included in the jar, which then produced a saturated atmosphere. This is not shown in this graph.

For desert burrowers : SEAL YOUR TANK!




A shot taken in the habitat of U.armatus after recent rains. Low rainfall area <200mm per year.

 

Rigelus

Arachnoknight
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Jul 12, 2006
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I'm guessing that theres some very fine measuring equipment involved when measuring the water loss from the scorpion while in a holding container without substrate but I'm curious Mark.....
How do you measure the water content within soil so accurately, is it again something so simple as a sensitive water meter.?

/Bryan
 

xVOWx

Arachnoknight
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Dec 21, 2005
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235
I think experiments such as this might be valuable to those attempting to breed H. arizonensis from North America. From what I've read no one has been able to raise this species past 4I or so. I would be curious to know if anyone has tried your 'sealed tank' method.
 

Mark Newton

Arachnobaron
Old Timer
Joined
Mar 9, 2007
Messages
401
I'm guessing that theres some very fine measuring equipment involved when measuring the water loss from the scorpion while in a holding container without substrate but I'm curious Mark.....
How do you measure the water content within soil so accurately, is it again something so simple as a sensitive water meter.?

/Bryan
I use jewellers scales that are accurate to 0.001g for weighing diamonds and the like. I have to cover my nose/mouth when weighing or wind currents change the reading and have doors closed etc. I remove the scorpion for weighing. I weigh the sand wet and dry to determine water content etc. Pretty straight forward.
 

Mark Newton

Arachnobaron
Old Timer
Joined
Mar 9, 2007
Messages
401
I think experiments such as this might be valuable to those attempting to breed H. arizonensis from North America. From what I've read no one has been able to raise this species past 4I or so. I would be curious to know if anyone has tried your 'sealed tank' method.
I wasnt aware of that. Thats very surprising for a scorpion that is commonly kept in captivity, that means they are all wild caught! I was under the impression that H. arizonensis was quite dry air tolerant as it is so surface active. Of course it depends on how much time it spends out and what the RH and temp is. I'm pretty sure I read a paper by Hadley that shows this species cannot remove water from substrate.

It would be wise to use the sealed method with this species as they are a desert burrower, or use mouse holes I think I read somewhere. Low water content in the soil and seal to create high humidity in a dry substrate.
 
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