Pyramiding of Shell (humid hides)

[anna m]

Thanks very much for this Kirkie.
There is always a contradiction in tortoise care isn't there?

[Kirkie]

Incidentally the point about the behaviour of wild tortoises differing from captive animals is a pertinant one. During the Summer, when outdoors, my Hermann's follow a different routine in comparison to when they are housed indoors. Outside they have an inital bask and forage in the mornings then hide away, burying under plants during the heat of the day, emerging in the evening for a further forage. Indoors they have a far greater tendency to bask and wait to be fed!

[anna m]

Originally Posted by Kirkie

Incidentally the point about the behaviour of wild tortoises differing from captive animals is a pertinant one. During the Summer, when outdoors, my Hermann's follow a much different routine in comparison to when they are housed indoors. Outside they have an inital bask and forage in the mornings then hide away, burying under plants during the heat of the day, emerging in the evening for a furhter forage. Indoors they have a far greater tendency to bask and wait to be fed!

Little articles

[alotoffluff]

Originally Posted by alicia

for my ibera i have a butter tub that i washed out and i stuck a washing up sponge to the top of it with string.
the i cut a little entry hole and they go in and out when they want.
i havent found one big enough for bobby yet though @

alice.
xxxx

Hi
Is the sponge wet or dry and do you put anything in the bottom of the butter tub?

[linda]

http://www.graeca-home.de/Krueger%202008%20e.pdf
sorry the pics wouldnt copy

Editha Krüger
Moist Root Shelters for Hatchlings
When raising juveniles of certain tortoise
species, one sometimes unfortunately observes
the development of deformations of the bony
shell, especially in the region of the back.
Discussions about potential causes of this
so-called “pyramiding” commonly revolve
around factors such as unnaturally accelerated
growth due to a diet that is excessive in
both quantity and protein (Highfield 2008),
insufficient intake of calcium (Frye 1991,
Gerlach 2006), or excessive intake of calcium
(Stancel et al. 1998). In recent years, a
latent dehydration has also been implicated
(Wiesner & Iben 2003). It is possible that the
formation of a humped shell results from a
combination of the above-mentioned factors,
since it appears to involve a dehydration of
the animals that, for currently unknown reasons,
is not compensated by the oral intake
of water (pers. obs.).
To remedy this problem, some breeders
recommend that juveniles be bathed on a
regular basis, as this enables them to absorb
additional moisture via the skin (Harless
& Morlock 1989). Most keepers have furthermore
changed to housing their Testudo
juveniles in a relatively moist environment,
especially at night. This measure may appear
to be counter-intuitive at first, since
one would expect the natural habitats of
these animals to be for the most part very
dry. However, the reasons why hatchlings
in the wild do not experience a comparable
dehydration presumably lies, next to their
naturally slower growth rate, in their much
more covert lifestyle. During their first few
years of life, juvenile Testudo spend almost
their entire time under the thick undergrowth
of the Mediterranean maquis and garrigue.
Fig. 1. Test of evaporation rates using
two fresh carrots.
Fig. 2. One carrot was stored on dry
quartz sand, while the other was buried
in it.
Fig. 3. After only one week at 21 °C
and ca. 50 % relative humidity, the
carrot lying in the open has shrivelled up
completely, even though it was thicker
originally, while the carrot buried in the
sand is still moist and crunchy...
RADIATA 17 (2), 2008 15
Moist Root Shelters for Hatchlings
In periods of inactivity, they frequently bury
themselves in the ground, typically in the fully
shaded root areas of bushes and shrubs. Here,
evaporation from the vegetation creates a higher
level of relative humidity than an overall
impression of the landscape suggests and the
climatological charts indicate, the latter data
usually being gathered at a point two meters
above the ground. Moreover, even when the
plants and soil are completely dehydrated,
they still reduce the air volume surrounding
the small animals and thus decrease the loss
of fluids through evaporation, much in the
same manner as dry cling wrap counteracts the
dehydration of groceries. The extent to which
being buried in dry sand reduces evaporation
is illustrated here by an example from the
plant kingdom (Figs. 1-3). In contrast, juvenile
Testudo in human care soon lose their initial
shyness towards their keepers and potential
predators and as a consequence retreat into
their shelters less frequently. Furthermore,
our lower air temperatures necessitate longer
and more dehydrating basking sessions,
since the ambient temperature almost always
ranges below the preferred body temperature
of these animals. In my experience, this increased
dehydration can be more effectively
compensated by providing soil- or root-based
dens at night (Fig. 4) than by raising the level
of humidity in solid shelter huts. The larger
air volume in these huts caused my juveniles
to dehydrate more even at increased humidity
levels than if their shell was in close contact
with a moist substrate. My initial concern that
spending the night in a damp environment
might lead to respiratory tract infections or
cause skin or shell diseases proved unfounded
in the Testudo graeca soussensis in my care,
even though this species is considered to be
sensitive towards moisture. Nevertheless, it
will be left to every tortoise keeper to take
into consideration the specific needs of the
species and individuals in his or her care.
I had the idea of creating underground dens
when my first baby Testudo graeca soussensis
ceased to bury themselves in the ground
shortly after they had hatched. They sat on
Fig. 4. Entrance to a shelter in the moist section of a terrarium.
16 RADIATA 17 (2), 2008
the moist moss lining their wooden shelter
hut rather than burying themselves under it as
I had intended. My older juveniles have not
turned out particularly
humped, but unfortunately
also not as
smooth as most specimens
living in the wild.
The hatchlings that
emerged from a clutch
that had been incubated
in a naturalistic manner
in a greenhouse (Krüger
2007) therefore
received neither a solid
wooden hut nor the
commonly used shelter
beneath a piece of cork bark in their hotbed. As
in the wild, the only cover available to them
consisted of soil and plants, mainly lavender,
moss and ground ivy. Within a short period
of time, the animals had established a system
of tunnels between the roots of the plants that
barely exceeded the height of their shells.
This was where the small tortoises spent their
time whenever they were inactive. In order to
provide such a natural shelter even after they
were transferred to their autumn quarters, I
built an artificial structure according to the
plan outlined below.
Using moist soil dens rather than a solid
shelter hut has by now been proving beneficial
in my nursery enclosures since 2006. All
animals have so far grown without developing
any recognizable humps in their shells. Because
hotbeds tend to heat up substantially in
full sun and thus have low levels of relative
humidity, the presence of the plants ensures
that they are watered on a regular basis, since
thirsty plants are far more obvious than low
humidity levels. At the same time, the young
tortoises thus find reliable protection from
both overheating and dehydration throughout
the year.
Owing to principal considerations, I water
the plants exclusively in the evening. This
ensures that there is sufficient moisture at
night, while excess water has dissipated into
deeper soil levels by
the next morning. This
permits the surface to
dry quickly during the
day, much in the same
manner as morning
dew.
Another advantage
of this low soil shelter
over a wooden hut is
that it does not subtract
from the available
ground space of
the terrarium or hotbed,
which is usually in short supply. On the
contrary, the low hillock above the root den
Editha Krüger
Fig. 5. Various layers of the plant brick.
Fig. 6. Growth after four weeks.
Fig. 7. The root system provides stability.
RADIATA 17 (2), 2008 17
forms a favourite basking spot with natural
plant protection. Heating the underground
tunnels at night is no problem either. A heating
cable of low wattage can be integrated
in the plant bricks from the beginning, or a
thermostat-controlled infrared spotlight can
be installed afterwards to gently heat the roof
of the shelter from above.
My by now one and a half year old juveniles
accepted their root shelter readily after being
transferred to their transition quarters, spending
the first night there without hesitation.
Over time, the newly set-up shelter integrated
progressively into its environment.
It even increased in stability, since the
plants will grow and intertwine with the
surrounding vegetation if the environmental
conditions are favourable. This renders
the root shelter portrayed here – besides its
function as a source of moisture – a valuable
bioindicator for harmful temperature peaks in
hotbeds and for adequate lighting conditions
in terraria.
A short manual for constructing a root
shelter
You will need:
A planting tray of adequate size, a firm but
pliable piece of fine wire mesh (e.g., snail
fence, 5 mm mesh), germination soil, grass
seed, 10-15 baby plants with small rootballs,
e.g., ground ivy, hawkbit, creeping Jenny,
wild strawberry.
This is how it is done:
• Cut the wire mesh to fit into the
planting tray; be sure to file down all sharp
edges. This mesh will later provide the necessary
stability to the arched shelter.
• Loosen the rootballs of the plants,
shake out the soil, and trim the roots to stimulate
new growth.
• Fill the tray 3 cm deep with germination
soil and cover it with the wire mesh.
• Add another layer of soil, insert
plants, and spread grass seeds.
Moist Root Shelters for Hatchlings
Fig. 8. The preformed shelter.
18 RADIATA 17 (2), 2008
Editha Krüger
• Leave for 4-6 weeks, then check for
rooting and if satisfactory, remove plant brick
from tray.
• Bend the plant brick carefully along
its longitudinal axis to form a semi-tube

[Alex]

Its a very interesting paper. You can read the whole paper here
http://www.amazonreptile.com/tortoisepyramiding.pdf

Check out this from richard Fife
http://www.reptileforums.co.uk/shell...yramiding.html

and this interesting view from Andy Highfield

"Even in habitats such as the Sonoran Desert in AZ, or in T. horsfielldi burrows in Central Asia, burrow humidity very rarely exceeds 45%. It is frequently very much lower, below 20%.

The highest burrow humidity I have personally recorded was 60%, in winter, in Morocco. External humidity was high that day at 20%. By contrast, external humidity in North American deserts can be as low as 4% and similar levels are found in the deserts of Central Asia."

Here are some interesting related to this topic journals:

Wiensner C.S, & Iben C, 2003. Influence of environmental humidity and dietary protein on pyramidal growth of carapaces in African spurred tortoises (Geochelone sulcata).

Stancel C.F, Dierenfeld E.S, Schoknecht P.A, 1997, Calcium and phosphorus supplementation decreases growth, but does not induce pyramiding, in young red-eared sliders, Trachemys scripta elegans

Hatt J.M, Clauss M, Gisler R, Liesegang A, Wanner A, 2005, Fiber Digestibility in Juvenile Galapagos tortoises (Geochelone nigra) and Implications for the Development of Captive Animals

Gerlash J, 2004, Effects of diet on the systematic utility of the tortoise Carapace, African Journal of Herpetology Springer US

Furrer S.C , Hatt J.M, Snell H , Marez C, Honegger R.E, Rübel A, 2004 Comparative Study on the Growth of Juvenile Galapagos Giant Tortoises (Geochelone nigra) at the Charles Darwin Research Station (Galapagos Islands, Ecuador) and Zoo Zurich (Zurich, Switzerland),

Bulova, S. J. (2002): How temperature, humidity, and burrow selection affect evaporative water loss in desert tortoises. J. Thermal Biology (27):175-189

[Kirkie]

Hi Alex,

It would be interesting to know the source of the Andy Highfield quote and the context it's being used in. A TT article on microclimates (admittedly not specifically humid hides but does say that suitable substrates and hides prevent dehydration and that animals with access to them showed smooth shell growth) http://www.tortoisetrust.org/articles/microclimates.htm

I think the thing with humid hides is they are not the magic answer to pyramiding and should be used as an option in conjunction with suitable feeding, hydration and heating.

I like them because as I've said earlier my Hermann's behave differently when indoors (with a tendancy to bask and generally doss around) in an already drier environment than they encounter outdoors. It may be that humid hides minimalise fluid loss by evaporation?

Anyway my torts like sitting or digging in in them so I'll stick with them, they have the option of not going in there after all

[Alex]

Hi Kirkie

From what I have read humid hides do seem to prevent pyramidal growth and I would encourage their use.

If you scroll down the first page, Andy gives his views
http://www.reptileforums.co.uk/shell...yramiding.html

Taken from

Bulova, S. J. (2002): How temperature, humidity, and burrow selection affect evaporative water loss in desert tortoises. J. Thermal Biology (27):175-189

Basically a lot of desert tortoises do not have areas of high humidity but still have smooth growth, leading to PGS.

From what I have read a possible reason why humid hides are successful in preventing Pyramidal growth syndrome is they help prevent dehydration and dehydration may reduce the intracellular and intercellular pressure on the soft cartilagineous tissue at the growing gap area.

[Kirkie]

Alex,

Sorry that link is just taking me to the home page, do you have the title of the thread so I can have a look at it?

There is a thread on that forum in which Andy Highfield states that in every post mortem investigation of a pyramided tortoise he has been involved with, symptoms of Metabolic Bone Disease have been present, thus indicating a dietry rather than environmental cause (sorry if thats a bit of a summing up). I was intrigued by your Highfield quote as it seems to say that the the burrows of wild tortoises do not have significantly high levels of humidity, as if this was an arguement against the humidity theory where I have seen him support it, as a ingredient for prevention, elsewhere.

Again without seeing the context this may be an assumption on my part.

The point I was trying to make is that I think humid hides are a good thing, they replicate the climate my tortoises experience out of doors and there is significant evidence that their use has prevented pyramiding but ... other considerations such as good diet, UV and hydration are equally essential. A lot of new keepers are suddenly keen on making a humid hide and I think they should be aware that this is only one aspect of prevention. For instance a dehydrated tortoise will not regain fluid in a humid hide, the hide will just prevent further loss so hydration remains essential.

[Kirkie]

After trawling through a long and rather heated debate on another forum I came across this from Andy Highfield:

"A key conclusion of Weisner & Iben is that "areas with a relative humidity of 100% for hiding should be provided at all times".

One issue is that there is an assumption by many people that wild tortoises use retreats with this level of ambient humidity.

Field data does not support this.

The measurements that I took over an 8 year-period of Testudo burrows and scrapes at various locations in Morocco, Tunisia, Turkey and Spain revealed an average RH of 60%. The highest humidity ever measured was 76% following an extended episode of rain in Southern Morocco. That was unusual. The lowest burrow humidity measured was 44% in a very sandy habitat in Tunisia. The average external RH was circa 20% when burrow humidities of circa 60% were recorded.

This is based on more than 600 field measurements taken using laboratoy grade equipment and under the direction of a qualified soil chemist and geographer. These results were published some years ago in Chelonian Conservation and Biology.

Just an observation. I have not personally measured G. sulcata burrows, however."

This is also relevant from the same discussion and is posted by (I believe) the originater of the "root hide" paper I linked earlier.

'ld like to offer a theory for discussion on how three of the factors that are discussed to cause pyramiding, too much protein, too low air humidity and not enough calcium/vitamin D might work together in producing the carapax deformation which is so common in captive tortoises. My theory is based on an article by Bidmon and Jennemann, published 2006 in a German chelonian journal*.

Due to their more open way of living in captivity, lower humidity levels around the shells of hatchlings and very young tortoises might cause higher evaporation from the carapax along the clefts of the growth rings than they normally would experience in the wild. This could lead to locally reduced turgor pressure in the bone forming cells and thus to dents in the collagen matrix of the physiologically not yet fully calcified shell of very young tortoises.These - themselves flexible - dents in the bone become manifest due to the hardening of the initially soft new keratin directly above, which is formed along the dents.

Bidmon et al., who explained it about that way in a German hobby journal, believe low humidity to be the only cause of pyramiding. I disagree though; I believe that pyramiding in captivity is actually caused mainly by faster growth and to some degree by providing not enough calcium and/or UV-B. Nevertheless, to my own surprise I found that providing hatchlings with moist conditions during the night is even more effective in preventing the symptoms than my careful feeding regime. My first south Moroccan hatchlings did not grow as smooth as wild specimen, despite providing them with an all wild herb diet (ca. 30 species), plenty of calcium and direct sunlight in a large outdoor enclosure. With some of the hatchlings I therefore tried the "humidity theory" and it really worked. These tortoises are smoother than their siblings, despite otherwise similar conditions. My own explanation for this effect is that the fast growth of our too well fed captive tortoises produces very large - "soft" - growth rings, which are more sensitive to the ill effects of evaporation and local dehydration than the very narrow rings of wild specimens. As an engineer I know that a wide band is usually less stable than a narrow band and therefore more prone to form a collapsed dent. Slow calcification of the bone shell in captivity would enhance this effect or would at least leave young tortoises vulnerable over a longer period of life, thus producing wider amplitudes of the pyramids.

Together with a more secret way of living, slow growth, natural diet and sun light produces smooth shells in wild tortoises even in their drier habitats. Actually, it might not be necessary for the substrate to be humid at all in order to reduce evaporation from the shell. Complete dry sand probably does the trick as well! I made an experiment with two carrots, one laying openly, the other one was buried in dry sand. After only one week, the "open" carrot was completely shrivelled, whereas the buried carrot looked as good as new. It is very likely that burring themselves in dry soil in the wild reduces loss of water in tortoises in the same way. My theory thus could help explaining differences in smoothness in the wild in semi-arid areas, as different individuals might have differently effective hiding places as hatchlings. But young captive tortoises often grow faster even with a careful feeding regime and they very often loose shyness quickly and do not burry themselves underground during the night, rather sit in large wooden huts that do not reduce evaporation as well as close contact with soil. Above that, they need to stay much longer in the open for thermoregulation in the sun during the day, whereas young tortoises in the wild might find adequate temperatures for their metabolism underground. Thus it makes sense to provide captive hatchlings with rehydrating moist shelters for the night. I have a little article on this subject and photos of the carrot experiment online: http://www.graeca-home.de/Krueger%202008%20e.pdf