Carapace Like A Sponge

[Tom]

We all talk about how the carapace is a hard, impermeable, keratinous, shell, "like fingernails". On the other hand we caution against putting things like shell "conditioners" and olive oil on the shell because it is a living, breathing thing with feelings. This has often puzzled me. Is it a "dead" layer, like our hair? Or is it a living breathing membrane with nerve endings, more like our skin, with an outer "dead" layer and living tissue just underneath.

Well I've had a new observation due to my unique situation. I first noticed that my baby sulcatas shells looked more "ridgy" after being out in the sun and the hot dry air for a couple of hours. After a few minutes of soaking or spraying they look better and get back to "normal" very quickly. I initially attributed this to light refraction or some sort of visual "effect". Now I've got a whole bunch of these pardalis pardalis leopards. I got them within days of them hatching and they've been getting daily soaks, multiple shell sprays a day, high humidity round the clock and humid hide boxes. Their shells are perfectly smooth and looking great as they grow. Here's where it gets interesting. I started noticing that after sunning sessions their shells would look a little sunken in. The "shields" would actually appear to be sunken in. Almost like reverse pyramiding. It was much more pronounced than in the sulcata babies, but in hindsight it is the same kind of thing. Within minutes of being back in the water and humidity the shells round back out and look totally smooth again. Its as if the shell is a "sponge". As it dries out in the hot sun and dry air, it shrivels and sinks in. When you rehydrate it, it fills back in and expands, returning to its original wet shape and volume. This is another reason why their shells just look better wet in pics. The shell absorbs water, all the ridges fill in, and the shell has a smoother appearance. I don't notice this phenomenon on my older bigger torts, but I wonder.

I bring this all up because it HAS to have something to do with pyramiding. We've talked about not being able to explain EXACTLY what is going on with pyramiding at a cellular level. It is now overwhelmingly clear that moisture and humidity will prevent pyramiding, but I still can't tell you why on a biological, cellular level. Well I'm convinced that this has something to do with it. Its almost like "turgor" pressure in plant cells. Based on the study that Danny cited, I've been ready to agree that pyramiding is at least in part due to chronic dehydration and the resulting problems in hatchlings. Now, with these observations, I'm not so sure. I never thought of any of my previous leopard or sulcata hatchlings as sickly, dehydrated or unhealthy in any way. Quite the contrary, they all seemed very healthy to me and everyone who saw them. They were, however, constantly dry. Dry hot air outside, here in the CA high desert. Hot dry air under their CHE and basking lamps, on a dry substrate in their indoor enclosures. The only time their shells got wet was during an occasional soak. After which, I'd dry them off before putting them back on their rabbit pellets. ( For any newbies reading this, how I used to keep them is ALL WRONG!)

For all these years, all these desert species of torts have been growing up with their shells in this dried-up, shriveled state all the time. It is only due to my new way of raising hatchlings that I'm even observing these things. It seems that keeping the "sponge" wet and in its expanded, filled-up state during the first few inches of growth is the key to preventing pyramiding.

A note on humidity and its role in all this: When I recently was working in New Orleans in the Spring, I noticed that due to the high humidity (90's most days) if something got wet it stayed wet. I'd pour cold water on my shirt or my dog and despite being in the direct sun and 90-100 degree temps, everything would just stay wet. All day long. The only way to dry anything was to bring it inside the air conditioned hotel. So for our tortoises, humidity is a means of keeping things wet, once you get them wet. The more humid it is the slower the tortoise loses external moisture due to evaporation and internal moisture (hydration) due to evaporation through respiration. In other words, the more humid it is, the harder (and slower) it is for them to dry out, bringing their shells to that desiccated state that I've been noticing outside.

I'm looking forward to hearing other peoples thoughts and observations on this.

 

[Len B]

You may have something with this thought, Last Thursday Sept 30 we had several inches of rain,and during a break in the rain I went out to check on everything,Two of the MT Tortoises were getting frisky under one of the maple trees and they were DRY everything else was soaked and rain was still dropping from the trees, I thought this was strange, so strange that I took a few pics. This is something that I had never noticed before but I wondered how they dried off so quick.The pics show that everything is wet but the tortoises.

 

[Shelli]

It is very humid where I live here in the Caribbean (75-100%) all the full grown old aged red-foots i have seen have no pyramiding and I can assure you their diet is nothing like what most people feed on this board... the ones I see regularly eat grass all day and don't seem to have any other suppliment other than dog poo... :/

Edited to add I just checked humidity it is not even 10am yet and humidity is 90%.

 

[jackrat]

Great post.Tom.I have an antique male redfoot with a perfectly slick shell.When I wet the group down,you can literally see his shell drying.It isn't running off the shell.His skin even dries before the others'.All in this picture were sprinkled at the same time.He is on the far right.Compare his carapace to the rest of the group.This was taken within two minutes of being sprinkled.

 

[Tom]

Funny, I noticed that the first time you posted this pic. I hadn't even considered what you and Len have pointed out here about different torts drying out at different rates.

 

[Madkins007]

There is a difference between absorbent and permeable. The outer layers are keratin and such, and obviously swell and contract with exposure to wet and dry.

The question is- does this surface activity have a real affect on underlying tissues? The wetness should not be being 'sucked in' deeply if what we think we know about shell anatomy is accurate, but that does not mean that the underlying tissue is not responding somehow.

I have been wondering if there might not be a response in there somewhere that causes the various tissues to respond differently...

For example, and this is just a sudden thought, but... what if dryness 'locks' the last growth ring somehow so it does not 'flex' for the next one, and the new ring 'lifts' the old one?

Simple pyramiding does not seem to affect the bone, so maybe it is something as simple as keeping the new, sensitive, and very absorbent* new rings 'flexible' as the newest ring is forming? Whatever pyramiding is, it is happening right at the line between the newest rings on the scutes.

(*- we know that new rings can absorb water and swell- we see it all the time, especially on the plastron.)

Its an awkward analogy, but think about painting or staining something. You are always supposed to keep a 'wet edge' as you cover more area. If you let the edge of the paint dry and then try to paint past that point, you get a visible difference.

Here is another thing, Tom- if this is anywhere near the right explanation, then your misting experiment would be right, as would things like 'damp root hides' the article from Radiata mentions, and high humidity, and heavily planted/misted plants (that would moisten the shell as they pass), and other processes that people have tried with differing degrees of success.

It would also explain why HYDRATION alone is not doing the trick- it is not water from within that is doing it- it is simply dampness on the shell.

Dang- if this IS true, we might be able to develop some sort of ointment that is mostly water (like Aloe Vera, Spenco Second Skin, etc.) we can apply every so often to provide long-term moisture right on the shell, or maybe a sort of 'wet curtain' that would rewet the shell every time they pass by it.

Or, better yet- rig up a system where there is an automatic shower that mists/sprays your tort with water whenever it passes. Forget timer-based misters or hand misting all the time- let the tortoise and a sensor do it. You could even rig it so the substrate there is drained better or even recycles the water.

Exciting possibilities!

 

[DeanS]

After witnessing this at Tom's on Friday, I made some adjustments to my torts' regimen...I feed them, spray them and let them run around in the yard for a half an hour or so (supervised, of course). Then when they're ready to nap, it's off to the kiddie pool, hwere they run around again for 5 or 10 minutes, then find a spot where they just crash...usually it's in the water which I pre-fill and allow the sun to warm it up a bit...*NOTE: The pool is at about a 5 degree slant, so they can access the dry basking area which gets to about 125 degrees, thanks to the high desert heat and sitting on concrete.* So for the 4 hours or so that they spend in the pool they are in the water at least 2 hours (plus I manually splash them every half hour or so...to keep the carapacr wet) Then I repeat the first part of their day and when they settle down (usually around 4 or 5 PM), I put 'em in for the night! Once they settle into their Tortoise house...I give 'em one final spray...until morning.

 

[Tom]

Here is another thing, Tom- if this is anywhere near the right explanation, then your misting experiment would be right, as would things like 'damp root hides' the article from Radiata mentions, and high humidity, and heavily planted/misted plants (that would moisten the shell as they pass), and other processes that people have tried with differing degrees of success.

It would also explain why HYDRATION alone is not doing the trick- it is not water from within that is doing it- it is simply dampness on the shell.

Dang- if this IS true, we might be able to develop some sort of ointment that is mostly water (like Aloe Vera, Spenco Second Skin, etc.) we can apply every so often to provide long-term moisture right on the shell, or maybe a sort of 'wet curtain' that would rewet the shell every time they pass by it.

Exciting possibilities!

Sort of lends credence to the olive oil or mineral oil on the carapace theory, doesn't it.

I'm taking a leap here, but I would surmise that my hatchling sulcatas are so "healthy" from all the hydration and so "smooth" from all the humidity and shell spraying. My new leopard hatchlings are showing every indication of going the same way as my sulcata hatchlings. Just nothing but glowing health, smooth carapaces and good growth.

 

[Kristina]

I noticed the same "sunkenness" with my baby Cherryhead. I was keeping him in a sweater box, on coconut coir with a hide stuffed with damp sphagnum moss. I was not happy with the humidity level, and his scutes looked sunken in. The affected area was the scutes that he would have been born with. The new growth, the growth he had attained since hatching, was raised in higher ridges than the baby scales.

I switched his enclosure to a planted vivarium. Since then, he has remained smooth with no indication of the previous sunken look.

I do believe this was in direct correlation with the humidity level. Tyler Stewart mentioned something similar to this about his Yellowfoot babies. In both the sweater box and the viv, the baby Cherryhead was getting misted several times a day. But in the sweater box he was dehydrating faster. In the viv, he is doing fantastic.

 

[DeanS]

Sort of lends credence to the olive oil or mineral oil on the carapace theory, doesn't it.

I'm taking a leap here, but I would surmise that my hatchling sulcatas are so "healthy" from all the hydration and so "smooth" from all the humidity and shell spraying. My new leopard hatchlings are showing every indication of going the same way as my sulcata hatchlings. Just nothing but glowing health, smooth carapaces and good growth.

As I've witnessed, these torts are the healthiest babies I've EVER seen for their respective ages! I'm still blown away at the size of Tom's 3-4 month old sulcatas...they are all at least 1/3 larger than my yearlings and the Gpp babies show no vulnerability whatsoever...OUTSTANDING work...I see a new how-to book in the not-too-distant future...kneel before the GURU

 

[egyptiandan]

Here's something that might lend a bit of credence to Tom's theory. Scute material is thinest when a tortoise is a hatchling. Scute material isn't laid down at the edges of a scute like one would think. Each new addition/wrinkle to the scute happens underneath the original/hatchling scute part of the scute (the textured bit of scute). So as each bit of new scute is formed it's like growing a whole new scute. This means that as a tortoise grows older the hatchling area of the scute becomes the thickest in term of scute material and the last bits, furtherest away, the thinest. This is how some water turtles are able to shed their scutes once a year as they are growing new scutes every time they add size to their scutes.

Danny

 

[DeanS]

Exactly! Soaking and spraying as early as possible is going to be the key here...if you start as soon as the egg sac is gone and healed, you are not going to have to worry about pyramiding! It's a bold statement, I know! But there is just too much proof in the pudding right now. Remember! HEAT! HUMIDITY! HYDRATION! Those are the keys.

 

[dmmj]

could it be because of their still soft shells?

 

[PeanutbuttER]

So, how does this explain why the first few inches of smooth growth seems to dictate how the rest of the shell will come in? Ie, after they're a couple inches long then there's less risk of pyramiding?

 

[DeanS]

We all know how permeable a tort is to begin with...add the fact that the carapce takes some time to harden and voila! It's as permeable as the rest of the body and once it hardens and the tort has grown a few inches then it becomes a matter of maintenance rather than repair. It's all falling into place!

 

[Tom]

So, how does this explain why the first few inches of smooth growth seems to dictate how the rest of the shell will come in? Ie, after they're a couple inches long then there's less risk of pyramiding?

For sulcatas, the size where humidity doesn't seem to matter as much anymore is around 6-8", from what I can tell.

The pattern of growth, either smooth or pyramided, is established in the first few weeks of life. Once they reach a certain size it doesn't seem to matter what you do as far as humidity. This also corresponds to the time in the wild when they would start staying above ground more of the time.

As I said before, I don't see any of this "sinking" or sponginess in my adults. It must be that baby's scutes are thinner and more "spongy". With age and size the scutes seem to get thicker, tougher and lose their "spongy" qualities.

 

[jackrat]

Just my two cents worth.Could it be that the very thinness of the scutes in younger torts that is contributing to their deformation? As the scutes push outward in growth,wouldn't they exert an upward force on the center of the scute? If this scute is already conformed to a convex surface,(the plastron),the natural tendency would be to rise in the middle.Like pushing on opposite ends of an unstrung bow. As scutes grow,they exert an equalized force upon each other.In most scutes this force is transferred from multiple edges of the scute,pushing the center up.A softer,more pliable(hydrated) scute would be more able to resist transforming this lateral force into a vertical force.While we're making analogies,think of it this way.Push on the ends of a cooked lasagna noodle.It won't rise in the middle like the unstrung bow did. A thicker scute should be able to take the lateral force with less chance of deforming vertically,just as the bow is a lot harder to deform than the noodle.Just throwing this out there,for what it's worth.

 

[Madkins007]

Sadly, I KNOW that smooth Red-foots can start to pyramid even after a couple years old. The individual bumps are more rounded or flat-topped, but they happen.

If the key really is keeping the active growth areas damp, then using oils/lotions to 'trap' oils sure might possibly help.

I'm looking at my copy of Obst's 'Turtles, Tortoises and Terrapins' and on p.170 is a simplified drawing of what Dan describes.

As the new growth comes in, it is a thin piece under the old one, but the growing edge is sort of tucked into the groove between each scute, like the edges of a fitted sheet. As the tort grows, the curved 'tuck-in' edge is sort of pulled out and flattened to allow the next one to develop in the groove.

What if the whole issue is just making sure the new lamina is soft enough to flatten as it comes out of the groove for the next one? This might also explain why when we see a cut-away of the pyramids they look spongy.

Let's build an imaginary bed- it is an air bed that gets longer and wider as you inflate it. Next, put a bunch of fitted sheets on it, the biggest on the bottom, and each one on top being a bit smaller.

As we inflate the bed, the sheets SHOULD smoothly ride up and slip off, collapsing into a thin heap on top. If we starch the sheets, to simulate dryness, they would still pop off, but form a fluffy pyramid as they did so.

The evidence for the theory might be as simple as finding, cutting, and carefully examining the scutes of a pyramided shell. Is the perimeter of the lamina curved or somehow thickened compared to a non-pyramided shell?

I think we have a solid working theory and/or care suggestion here! "Keep the new growth on the shell from drying out, especially on younger tortoises." Or, maybe "The younger the tortoise, the more important it is to make sure the shell does not get too dry."

 

[jackrat]

Just my two cents worth.Could it be that the very thinness of the scutes in younger torts that is contributing to their deformation? As the scutes push outward in growth,wouldn't they exert an upward force on the center of the scute? If this scute is already conformed to a convex surface,(the plastron),the natural tendency would be to rise in the middle.Like pushing on opposite ends of an unstrung bow. As scutes grow,they exert an equalized force upon each other.In most scutes this force is transferred from multiple edges of the scute,pushing the center up.A softer,more pliable(hydrated) scute would be more able to resist transforming this lateral force into a vertical force.While we're making analogies,think of it this way.Push on the ends of a cooked lasagna noodle.It won't rise in the middle like the unstrung bow did. A thicker scute should be able to take the lateral force with less chance of deforming vertically,just as the bow is a lot harder to deform than the noodle.Just throwing this out there,for what it's worth.

Sorry.I meant to say the convex surface of the carapace,not the plastron.

 

[chairman]

The effect that Tom has noticed on his young sulcatas is very apparent in my adult Home's hingebacks. I have one male in particular, who is much lighter than any of my others, whose shell really starts to look like it is flaking up at the edges when he lets himself dry out too much. The ridges are pretty extreme- they elevate about 2 mm above normal. After a good soak, his shell returns to its normal smoothness. My darker shelled hingebacks have a similar response, but it is not as pronounced. I'm not sure how much it relates to pyramiding since smaller torts are usually harder to pyramid than bigger ones, and hingebacks have very weird shells compared to most other tortoises.

As I type this I begin to wonder if the darkness/lightness of a tortoises shell affects pyramiding somehow. Young sulcata with light shells pyramid, older sulcata with darker shells don't pyramid very easily... and isn't there a blonde sulcata on here that is pyramiding even though its cage-mates aren't? But then again, aldabs and stars grow pretty bumpy, and they're pretty dark, so there has to be a little more to it than just color alone.

However, I do agree with Tom, my hingebacks do appear to have pretty "spongy" shells.