#35 - CASA DE TARANTULA #1

With this entry I start a series on tarantula enclosures. Blog #16 - "S.A.D.S." showed some of my preferred methods of raising young tarantulas, but this series will focus more on adult housing for various types. It will be an ongoing series that will run concurrent with the Tales from the Field series I recently began.

Dave Marschang asked in a blog comment about moisture for burrowers. He wrote: "What do you do about the burrowers who burrow to the bottom? flood their burrows?" He didn't specify exactly which burrowers he was referring to. My answer would be different if it was a scrub desert or grassland obligate burrower like America's own Aphonopelma or South American Grammostola (which can be kept without a deep burrow), an African burrower like Monocentropus balfouri (requiring some ability to burrow, but commonly kept with perhaps 6-8" of substrate) or a Old World tropical burrower like Haplopelma (requiring a great depth of moist soil). Since moisture is most important for the latter I am going to assume he did, in fact, mean popular Asian burrowers of the family Ornithoctoninae (e.g., Haplopelma, Ornithoctonus) and Selenocosmiinae (e.g., Chilobrachys, Orphnaecus).

I don't work with these type of spiders any longer, but I used to breed quite a few of them. They are often referred to as "pet holes" because proper housing includes providing a great depth of moist dirt, which they will burrow to the bottom of. The "cobalt blue" (Haplopelma lividum) is one of the best known of these spiders, and I have often told customers to take a photo of their pretty black and blue spider and tape it to the enclosure because if properly housed the spider will never be visible. They are rarely seen except during the dark of night when they may be near the top of the burrow waiting to ambush prey. In America, Chris Allen is someone known for his love of these types of spiders. The keepers that I always associate with them are Volker von Wirth and Martin Huber, both of Germany. Volker is well known for his taxonomy work with these spiders in addition to captive husbandry and propagation. Martin was well-known also as a breeder with a preference for Asian burrowers, but today he has largely disappeared from arachnoculture and is instead working with frogs, especially Phyllomedusinae (i.e., neotropical leaf or monkey tree frogs such as Agalychnis and Phyllomedusa). The housing that was popularized by both Volker and Martin is what most of us used to great effect, and it utilized a unique method for adding water to these deep burrowing tarantulas that lived deep in the dirt. Many of the images contained herein are from Volker and Martin who shared them with me for my keynote lecture at the 2007 British Tarantula Society Lectures.

© von Wirth or Huber

This first image shows a very simple "cereal container" style housing for Haplopelma lividum. These containers are tall and narrow and you can pack dirt around a large tube or broomstick near one front corner to create the burrow for the spider so it will be easier for you to view. I have used very similar containers, but usually chose somewhat wider and taller Rubbermaid containers that had space for larger species like big Chilobrachys or Haplopelma schmidti.

However, what is important to notice in this image is the row of holes at the bottom of the front. The upper ring of holes is for ventilation, but the bottom holes are both for soaking and draining (I'll explain this below). European keepers have a penchant for making their own terrariums out of glass and the next images from Volker or Martin shows how theirs looked and how they were filled around a pole to create the burrow.

© von Wirth or Huber

Here you see the top view on the left and the front view on the right. Note the perforated aluminum used at the rear of the top for ventilation, the sliding glass top and the same perforated aluminum at the bottom of the front to provide for the soaking and draining that I will describe.

The next photos show this type of enclosure in preparation and use. In the second image the cardboard box is being used as a funnel to pour dirt into the narrow enclosure. This type of housing is outstanding for keeping any of the Asian burrowers and could also be used for some New World species with similar habits.

© Martin Huber

© Martin Huber

© Martin Huber

© von Wirth or Huber

What is interesting about this type of housing though is the method of watering the enclosures. This brings us to Dave's question. And a photo is worth a thousand words ...

Periodically the enclosures would be set into a large tub of water. You can see in the enclosure nearest the front that the spider is at the surface. What happens is the water enters the enclosure at the bottom of the front and rises to the water depth in the tub. The spiders will escape the sudden flood by rising up their burrows and will be safe. The soil is "re-soaked" and then when the enclosures are removed the water will drain back out the "grating" of perforated metal or the simple soldering iron melted holes in the case of our first image of a plastic "cereal container" version of the same enclosure concept. The water is allowed to fully drain before the enclosures are returned to the shelves and eventually the spider will descend back to the chamber at the bottom where it lives.

© von Wirth or Huber

This is a very innovative method that I used for years. But let's talk about adding moisture to the substrate of burrowers that don't require the same elevated humidity and deep burrows. I have talked before about "moisture strata" with regards to substrate. What I mean by that is that the depth of substrate is stratified into varying degrees of moisture, with the bottom wettest and the top driest. For example, if I have six inches of soil in an enclosure for something like M. balfouri I may want the bottom two inches to be moist, the middle two inches to be damp and the upper two inches to be mostly dry. This is easily accomplished if you pour water down one corner or along one side of the enclosure. I also like to use long oil funnels that you can press down to the enclosure's bottom so the water is fed directly to the lower levels. In smaller containers a turkey baster can accomplish the same thing, and in vials you can make do with a pipette. Or just take a pencil or wooden chopstick and push down into the substrate as deep as possible along one side. This will break the "surface tension" and allow the water to percolate to the bottom. The idea behind "moisture strata" is to make the surface that is in contact with a terrestrial spider or a burrower that is in a shallow scrape relatively dry, but have a fair amount of water content below that evaporates and creates natural humidity.

The following two images show how I house my Harpactira. This plastic storage container has two large vents at each end (2" diameter hole saw cut holes covered on the outside with aluminum insect screening affixed by hot glue). This particular enclosure holds a subadult female H. marksi. I don't provide a great depth of substrate and the enclosure is both well-ventilated and kept fairly dry. What I do is provide a 2 oz. condiment cup of water, which really isn't for drinking except in an emergency*, but rather it is a small pool that I can overflow soaking the substrate in only one area of the enclosure. If the coco substrate becomes overly dry I will also pour water down along the length of the side as well. Note in the first photo how the coco is clearly darker right around the water cup (sprig of plastic plant is to prevent drowned crickets - never use cotton or paper towel or anything else that will foul and "breed" bacteria). The color of the coconut coir is a guide to how moist it is. You will also see that it has been moistened along the left side - the same side that the water cup is on. However, about 75% of the area is mostly dry including the area where you can see the silken entrance to the spider's shallow burrow.

© Michael Jacobi

© Michael Jacobi

I use a larger version of this "tub" with the same vent layout for my M. balfouri, and for that species I provide perhaps six to eight inches of substrate instead of the three to four you see here. However, my method of watering is the same: overflow the water dish for at least several seconds so that one corner of the enclosure is moist and, if necessary, also pour a bit down the length of one side. But I am always careful to not add too much water for "scrubland" species like Harpactira and Monocentropus.

* I have a saying that a tarantula never needs a water dish until it needs a water dish. Think about that ... none of my arboreals have them. They get moisture from their food and their enclosures are misted once or twice a week to elevate the humidity. If they really need to drink they will come out and use the droplets on the plants or the side of the glass or plastic at that time. Many are in natural terrariums with live plants and I water the plants and humidity is maintained by plant respiration and water evaporation. However, I do like to put a small dish (usually two 2 oz. condiments nested together; the bottom is the placeholder and the top is the disposable water container) in the enclosures of my African terrestrials (and recommend for other dry climate spiders). As discussed, I primarily use it as a point to pour water to re-moisten the substrate. They may never drink from them. But that one time that they have become too dry, or too underfed or too warm or too whatever they may seek a drink, and then it being there is the difference between life and death. Hence, I refer to them as " for emergency use". They don't need them ... until they do.

I hope you've learned something from Casa de Tarantula #1. In the second installment of this new series I will show you how to make a simple and perfect breeding enclosure for Poecilotheria using a large cereal container.

All the best, MJ

#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.