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Moist substrate - necessity or myth?

Discussion in 'Tarantula Questions & Discussions' started by smitje, Mar 18, 2017.

  1. smitje

    smitje Arachnosquire Active Member

    Im running a little experiment with my T's for about a month now.

    Most keepers notice that species kept dry can be found by their water dishes far more often then species living in a moist environement. I made a mistake with my avic setup, far to little substrate so it dried within an hour or so. Bad for the avic as you normally read. It did have a waterbowl and I noticed her drinking from it a few times. She just molted and looks fine.

    Why? She is supposed to be kept at high humidity. But is this also the case when they have access to fresh water all the time? Do they evaporate less in a humid environement so they drink less often? Can they compensate this by simply taking a zip of water?

    All of our T's are kept dry now, No mites, No molt, with fresh water replaced 2 or 3 times a week. So far all of them are fine, even my sazimai can be found at her waterdish sometimes as before I never saw her leaving the burrow.

    Has anyone ever tried this before? Is moist substrate really a necessity? Is humidity important at all when they have access to fresh water? Maybe its my own preference leading me here because I dont like moist enclosures that can produce molt and mites pretty fast.

    We have 20 different species at the moment, i will keep this post updated for half a year or so. If my T's start to show signs of ill being or even die we will have to stop ofcourse. For now, after a month No signs yet.
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  2. Andrea82

    Andrea82 Arachnoprince Active Member

    Caribena/Ypyrapora/Avicularia species don't need moist substrate. Moist substrate and high humidity are not the same. You can have high humidity without moist substrate by adding a large waterdish in the enclosure, but keep the sub dry.
    Are you running this test on above mentioned species? Make sure to have adequate ventilation, or you will kill them with all the moisture and stuffy enclosures.
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  3. smitje

    smitje Arachnosquire Active Member

    Im running this test on 20 different species. I expected people to dampen their soil especially to increase humidity. The latter is the thing I am trying to avoid, enclosures that are easily affected by molt and maybe worse mites. Both dont do well on dry surfaces even when humidity is high.

    So why overflow the water dish, spray the enclosure or water the soil if it is not for elevating humidity?
  4. The Grym Reaper

    The Grym Reaper Arachnoknight Active Member

    Avics do perfectly fine with dry sub, plenty of cross ventilation and a large open water dish, in their case the larger sized water dish provides adequate humidity for the enclosure, there is no need to moisten the substrate as well.

    As for the others, I'm sure there are plenty of humidity-loving species that will survive on dry substrate but they won't exactly thrive (I could keep my Nhandu and Acanthoscurria sp. bone dry but they appreciate me wetting parts of the substrate/overflowing the water dish now and again), them hanging out by the water dish all the time or constantly drinking the water dish dry is them trying to compensate for the enclosure/substrate being too dry, some species have a very narrow range of humidity requirements meaning that they will refuse food and eventually start to go into a death curl if their enclosures dry out too much (e.g. some fossorial species, T. blondi).

    I don't have a problem with mites or mould in my more humid enclosures because, since the onset of winter, they now have populations of springtails in them, free clean up crew and they're a good indicator that I'm keeping the substrate moist enough :smuggrin:.
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  5. Rittdk01

    Rittdk01 Arachnosquire

    I leave a portion of the substrate a bit moist for most of my tarantulas. If they want the extra moisture they will lay where it has been sprayed, if not they stay in t he dry substrate. I move the moist area around and have no molding issues this way.
  6. smitje

    smitje Arachnosquire Active Member

    I understand. As soon as I see them hanging out at the waterdish a lot its to dry and I will add water. But for now I see them occasionally, maybe once a week or once every 2 weeks. They eat well and look good so I would say they are perfectly fine (for now) and not just surviving. How do I know if its thriving? I'm pretty sure very few keepers have all the natural settings in place, things like temperature, humidity, day/night rythm and so on. People keeping over a hundred species from all corners of the world in one room..... Thats just not possible.... big question I guess: do the T's care? I want to avoid any trouble with PETA and really love our spiders :)

    Maybe a good question for the breeders, do T's pair when humidity, either soil or air, conditions are off? Any animal into producing offspring is a pretty happy animal I guess......
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  7. smitje

    smitje Arachnosquire Active Member

    Im not sure why but as soon as I keep my soil moist it molts fast, a cricket will have some molt on it after just a day. When i take it out a chunck of soil comes with it, also molt. I have them in critterkeepers so there is plenty of ventilation.
  8. BobBarley

    BobBarley Arachnoprince Active Member

    Depends on the species. Some need it dry, some don't. I made the grave mistake of keeping one of my N. incei slings too dry, and it passed. :( However I now make sure my other 4 are sufficiently moist.
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  9. EulersK

    EulersK Arachnoengineer Active Member

    Some species require humidity to be comfortable, and often need it to live. My T. stirmi has a 5" water dish, and she still needs that substrate moist. You've already got a story of someone losing a spider due to low humidity. You don't need to test anything, we're pretty darn sure which species need it and which don't.

    In this hobby, we've got tarantulas from every continent on the planet. Spiders from the muggy rainforests of the Amazon share a room with spiders from the driest deserts in the world. It's our job to make them as comfortable as possible, and letting humid species dry out isn't very humane in the same way that keeping an arid species moist is cruel.

    Mold is easily resolved by spot cleaning and (if need be) springtails. Mites are more often than not harmless and in fact beneficial. These are minor issues.
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  10. Venom1080

    Venom1080 Arachnoking Active Member


    Well, let us know when your tropical species start dying off.. seriously, this is a useless experiment that will probably lose you a few spiders.
    On what earth can spiders that come from jungles in deep burrows live comfortably beibg kept like a porteri. There is a thing called spot cleaning, it's normal for a bolus to mold when left in a humid environment. It's no big deal. High vent or not.
    Try raising Lampropelma with this theory of yours.
    I'm all for experimenting with new things as this hobby is still young, but for the sake of your spiders , don't try to repeat mistakes the first keepers figured out when this hobby began. If it ain't broke, don't fix it.
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  11. smitje

    smitje Arachnosquire Active Member

    Alright, bad idea, point taken.

    Go easy guys, Im keeping them for a year now and am trying to find my way. I am not trying to take a piss or anything. It's just pretty hard to find solid information when it comes to T's. To many contradictions on the internet, thats why I post here and on the dutch forum. I know the people there and on arachnoboards are passionate about the hobby. Still I find it hard to filter facts from opinions at times. Hope you understand.

    I appreciate your advice and comments!
  12. cold blood

    cold blood ArachnoGod Active Member

    "Moist substrate - necessity or myth?"

    "She is supposed to be kept at high humidity. But is this also the case when they have access to fresh water all the time? Do they evaporate less in a humid environment so they drink less often?"

    The "myth" is in humidity and some people's belief that its numbers are critical. The real deal is damp substrate. When you see "needs high humidity", what it should read is "moisture dependent"...as in they require moisture in the substrate.

    Tarantulas can drink water from damp substrate...not sure how good they are at extracting it from the air.

    The ambient humidity in your specific area will dictate how much water that means adding. When its humid outside, the substrate will hold moisture longer, so you will need to add less water to the sub (often just a sprinkle), much less often. In areas of very low humidity like a desert or the cold north during winter, you will be pouring water on the sub on a regular basis as it dries very quickly.
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  13. cold blood

    cold blood ArachnoGod Active Member

    They seem to pair at any time just fine...but many species do like more moisture when laying those eggs. Spring rains are not only a trigger for ts to molt...but also to drop sacs very often.
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  14. smitje

    smitje Arachnosquire Active Member

    Thanks, this is the part that got me confused. I didnt realise they where actualy sucking up the moisture from the soil. I was under the impression that wettening the soil was done to raise relative humidity in the enclosure to prevent T's from evaporating to fast. Live and learn. Still leaves me with another question, if it uses the soil to drink from, why couldnt it just use the waterbowl instead? They live in small enclosures so it's not much of a walk for them to reach the water?

    "Our greatest glory is not in never falling, but in rising every time we fall" ;)
    Last edited: Mar 19, 2017
  15. smitje

    smitje Arachnosquire Active Member

    Again Im not trying to be an ass but another question comes to mind. Does the skin structure of a T change over time? As in mentioned above "try to raise a lampropelma" or the N incei. Are slings more supceptable for low humidity conditions then their older counterparts? Or is this simply because they are much smaller and things happen faster?
    Last edited: Mar 19, 2017
  16. boina

    boina Arachnoknight Active Member

    I just wrote about that in another thread, so here's the short form: In nature, Ts live in hiding places or burrows, most often with no water source available - Ts won't cross 100 m of open space just to reach water. Accordingly, they often don't seem to feel "thirst". They just wait around for the next juicy prey to rehydrate. In nature prey is scarce and they are nearly always ready to eat. In our care however, they are very well fed, so they often won't take the prey they'd need to rehydrate. It just doesn't "occur" to the T that it can walk over to the water bowl and drink in this situation, because for the last 100.000 or so years it was not feasible for it's ancestors, so this "idea" is just not in it's behavioral repertoir.
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  17. creepa

    creepa Arachnoknight

    But in nature you have dew every morning it can drink and in tropical forests you have moisture in the air so they dont have to drink, but in he hobby it is difficult to maintain an 80 to 95% humidity so the spider will walk to the waterdish/wet corner if needed...
  18. boina

    boina Arachnoknight Active Member

    The question was about why moisture dependent species don't just rehydrate using a water dish. Since they don't what you are saying can't always be true.
  19. smitje

    smitje Arachnosquire Active Member

    But why? How does this mechanism actually work? Why can a Chromatopelma coop and a lampropelma not? Skin density? A different way to proces moisture? Sensitive or different booklungs? Or really just evolutionairy, some know when to drink and others just dont?
  20. Andrea82

    Andrea82 Arachnoprince Active Member

    Now this is a good question i would like to have answers to myself :)