#12B - PART TWO: THE MOISTURE CYCLE - HUMIDITY & HYDRATION

In today's primary blog (#12 - SUNDAY, FUN DAY - A P.S.A.) I discover my preference for coconut coir as substrate. Mike Schneider post comments and questions on my Facebook page that I asked him to copy and paste as a comment on Blog #12 so everything was tidy and in one place. This seems like the best way to keep in context and make it accessible to Blog readers. I still haven't figured out how Blogger works, especially since it is under Google's world domination, so I just announce each post on FB. But the Blog is a non-Facebook project and I'd like to keep all comments and questions in one place.

I'm going to copy and paste Mike's comments here to make things easier:

"Eco earth dries out very quickly it seems and I don't even keep my spiders that warm. I used to use it exclusively, but now I just used plain old top soil from home depot or lowes. I like the fact that it holds the humidity better and I can compact it down more. I don't like giving my spiders a home full of loose substrate. When I used to use coco coir I'd notice as it dried out over time it became super crumbly and burrows would collapse. A lot of time a separation would form between the wall of the tub and the substrate. I'm not even sure why this happened but it did and that annoyed me too. 

How often do you mist everything down to keep the coco from getting like that? Have you ever noticed any of the difficulties with it that I did?"

This touches on what I refer to as "The Moisture Cycle". It is a process of natural humidity through evaporation. It is a cycle because conditions aren't unnaturally static; sometimes it's moist and humid, but with GOOD PROPER VENTILATION there is a drying between. This is natural even in the equatorial tropics. Trust me, I've been there. You may think it is humid constantly, but night brings change, clouds bring change and, of course, rains bring change. And in many tropical regions seasons are about wet and dry, not hot and cool. Spiders do not have the monotonous, mostly static environmental conditions that keepers tend to force upon them.

So Mike asked specifically about EcoEarth (coco coir) drying "very quickly". He later mentioned a separation between the enclosure side and the substrate. Yes, this will happen if you don't have a routine/schedule of remoistening the substrate.

My goal is to keep moisture in an enclosure without creating any wetness or stagnation. Ventilation is a big key to this. But to keep moisture you need to be regularly adding more water. As I wrote earlier, I use exactly 96 oz. of water to one brick of EcoEarth. This is perfect. It is now my goal to more or less have this be the ideal average with periods moister and regular periods drier.

You see, tarantulas are hydrated by the moisture in the food and the moisture in the air that passes through their book lungs. They shouldn't need to drink. I do use water bowls (2 oz. condiment cups, mostly) here and there, but I focus on feeding food that has been gut-loaded and well hydrated itself. Water bowls are an insurance policy. Generally, they'll be filled with dirt or covered with silk as they are just another terrain feature or obstacle for the tarantula. But when they have fresh water access if there is the one time when whatever reason makes that spider dehydrated it needs to drink NOW! So the dish may never be used for years and then all of a sudden it becomes the safety net between live and death. NEVER include cotton balls, sponge, paper toweling or anything else in a water dish to breed bacteria and scum - use small pebbles or a piece of plastic plant or a bit of popsicle stick to prevent crickets and drowning in the water bowl.)

So that covers hydration. But how should humidity enter the enclosure? It isn't the rain that brings the long lasting increase in water content in the air (humidity), it is the evaporation from the ground it has seeped into over time. I re-water my enclosures regularly and then let them get pretty darn dry before doing so again. I mentioned in the earlier blog the use of an oil funnel with a long tip, which is great for poking down to the bottom depths (strata) of substrate so you can soak the bottom third, or maybe half, but keep the upper strata mostly dry, perhaps just a bit moist from a gentle misting. The spider than is in contact with slightly moist to dry conditions and beneath the ground a reservoir of water is evaporating over time and keeping moisture content IN THE AIR. If you don't have a long oil funnel a turkey baster also works great for this purpose. But in enclosures with a moderate depth of substrate (my Monocentropus and Harpactira have maybe four to six inches) it's just as easy to just pour water down the side or in a corner. Often I just fill the water bowl and let it overflow for ten seconds or so. The water percolates to the lower strata and is my "humidity reservoir" and the top of the substrate, which as I mentioned often has bone dry coarse loose Coco Soft substrate, doesn't get the tarantula's feet wet. 

***I NEVER LET MY ENCLOSURES GET WET. I use substantial ventilation to ensure that my Moisture Cycle is a regular and repeating gradual change from moist and humid to dry. So far I have just been referring to routine husbandry. This Moisture Cycle becomes even more importis manipulated for breeding purposes when 

Maintaining moist coco takes regular maintenance like anything else. To answer Mike's question about the coco getting so dry that it shrinks enough that there is a gap between the substrate and the wall of the enclosure - I only see that if I have an empty enclosure in storage that still contains the substrate. Otherwise each of my enclosures is getting more moisture weekly, bi-weekly, monthly - whatever it takes and whatever is appropriate based on species and enclosure. I never let them get bone dry even for my South African Harpactira or, for example, a true arid climate species like Chromatopelma cyaneopubescens.

Scott Szafran commented on my FB page that he was surprised he never thought about using a pipette instead of the harder to use syringe. So I posted this pic to show him the disposable cheap 3 ml pipettes I use.

You see I don't pressure wash my spiderlings. Misting can be done properly if you are careful and have a light touch and avoid the spider. Some people like to form some droplets for their spiders to drink from (again, IMO, it should be getting plenty of water from its prey items instead). But I rarely mist spiders kept in vials. Vials are death chambers because they are usually only ventilated with pin holes. Check out the pic at the bottom to see how mine are ventilated. This is all about the Moisture Cycle. Re-moisten substrate (and/or a little misting spritz), but it should dry within, say, 24 hours, and then be repeated. If you keep misting and make stagnant conditions you will kill spiders. And this is what has given Avicularia spiderlings an undue reputation as being hard to raise - a subject I will cover in great detail in a blog in the net week. So instead of misting spiders housed in vials with each feeding I evaluate how much moisture content is in the substrate. You get used to the shades of brown that the coco is depending on how "wet" it is. If it looks good the spider just gets fed. If it looks like a touch of more moisture is in order I squeeze 3ml into the vial and move on to the next.

This is one of the hundreds of 50 dram vials I use to raise Pachistopelma, Avicularia, Poecilotheria, arboreal Ornithoctoninae, etc. No nail holes. A one-inch hole covered by screen. This is the only way you can create The Moisture Cycle in such a small container. You have to add maybe 2ml of water and then just feed the spider well until the substrate lightens in color indicating its dry and then run another few milliliters of water down the side of the vial. Note that I also use a bit of beaked moss or sphagnum moss on top of the substrate, which helps slow down the drying process.

But coco coir dry enough to shrink away from the sides of an enclosure has not been maintained with the periodic addition of water. And those bone dry conditions are not suitable for tarantulas. Water needs to be added as appropriate for the species and the type of enclosure and its ventilation. It's a balancing act, but just something to evaluate at each feeding.