# The Air Space in the Egg



## Yvonne G (Apr 4, 2019)

A couple days ago I was reading a very old thread and Anyfoot made a comment wondering if the air sac inside the egg had anything to do with if the baby tortoise is prone to pyramiding or not. I can't find that post now, but it was an interesting idea. It was something about a whole clutch of his eggs, some had larger air sacs than others. And of the hatched clutch, being kept the same way, all in the same enclosure, some pyramided and some didn't. He was wondering if the air sac had anything to do with that.

Any discussion or ideas?


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## CarolM (Apr 30, 2019)

Yvonne G said:


> A couple days ago I was reading a very old thread and Anyfoot made a comment wondering if the air sac inside the egg had anything to do with if the baby tortoise is prone to pyramiding or not. I can't find that post now, but it was an interesting idea. It was something about a whole clutch of his eggs, some had larger air sacs than others. And of the hatched clutch, being kept the same way, all in the same enclosure, some pyramided and some didn't. He was wondering if the air sac had anything to do with that.
> 
> Any discussion or ideas?


Interesting idea. I have no clue, but would be interested in the response from the experienced members.


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## Ben02 (Apr 30, 2019)

Yvonne G said:


> A couple days ago I was reading a very old thread and Anyfoot made a comment wondering if the air sac inside the egg had anything to do with if the baby tortoise is prone to pyramiding or not. I can't find that post now, but it was an interesting idea. It was something about a whole clutch of his eggs, some had larger air sacs than others. And of the hatched clutch, being kept the same way, all in the same enclosure, some pyramided and some didn't. He was wondering if the air sac had anything to do with that.
> 
> Any discussion or ideas?


Sounds like a good idea, but what is the science of that.....how does that affect the tortoise?


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## wellington (Apr 30, 2019)

Ben02 said:


> Sounds like a good idea, but what is the science of that.....how does that affect the tortoise?


Where is the air sac usually placed? If it's too big and where the shell is, could it be exposing the shell to a dryer environment while still in the egg and out of our control?


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## CarolM (Apr 30, 2019)

wellington said:


> Where is the air sac usually placed? If it's too big and where the shell is, could it be exposing the shell to a dryer environment while still in the egg and out of our control?


And thereby predisposing the baby tortoise to pyramiding effects? Mmm interesting. But why would the shell be smooth for a while before it started pyramiding? As normally babies remain quite smooth until a couple of months into their growth. Could it be that the little bit of moisture that they gain while in the egg runs out and then the environmental factors start to play a role, and the size of the air sac in the egg would then be quiet important? in other words the amount of moisture that they can get inside the egg will be ingrained into their shell and will eventually need to be replaced by outside factors being the humidity of their enclosure and soaking etc.


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## Ben02 (Apr 30, 2019)

wellington said:


> Where is the air sac usually placed? If it's too big and where the shell is, could it be exposing the shell to a dryer environment while still in the egg and out of our control?


Surely it’s humid inside the egg?


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## Cheryl Hills (Apr 30, 2019)

It may also depend on how humid the incubator is. Humid incubation should transfer to inside the egg. The egg shell, I believe, is porous therefore you get a bit of exchange of air and humidity. Just my thought.


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## CarolM (Apr 30, 2019)

Cheryl Hills said:


> It may also depend on how humid the incubator is. Humid incubation should transfer to inside the egg. The egg shell, I believe, is porous therefore you get a bit of exchange of air and humidity. Just my thought.


Good thought. I liked Yvonne's original post but it had no responses and I am interested in the theory, so wanted to bring it up again.


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## wellington (Apr 30, 2019)

Ben02 said:


> Surely it’s humid inside the egg?


Yes I would assume so. However if the shell is within the air sac area, it may not be as humid? Just taking guesses on all this. I actually feel it has nothing to do with air sac but the heat/lighting we use and species.


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## Redfool (Apr 30, 2019)

I have read that an egg shell is porous for the exchange of oxygen, carbon dioxide also water. I can’t believe that when an embryo is ready to hatch that there would be any room for air space. I keep Redfoots who’s eggs chalk after being layed so a visible air bubble can’t be candled. It needs to push out at all sides of the egg and not swimming room. At hatch time the embryo is too large to accommodate the O2 Co2 exchange and stresses the embryo to break out. The albumin in the hatching egg can quickly turn to “glue” without humidity, complicating the hatch. I always mist pipping eggs. I believe pyramiding conditions come after hatching by a dry environment. A large air bubble may indicate less water content inside the egg


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## Markw84 (Apr 30, 2019)

Inside an egg there is the shell, then an outer membrane. These are what you see when a hatchling breaks out of the egg. The inner membrane is sliced by the egg tooth and the movement of the legs. The pressure from within breaks the shell easily. The embryo and yolk sac is inside an inner membrane. The air sac is between that inner membrane and the outer membrane. So the embryo is separated from the air sac by that inner membrane and not in contact with the air in the air sac. The air in the air sac would be at 100% humidity as it is completely enclosed and the air transfer and water transfer in/out of the egg is at a molecular level.

I see no way the size of the air in the egg could effect pyramiding. Pyramiding is caused by the way the seams of the scutes grow over the underlying bone. There is no seam growth while in the egg, and the "bone" is cartilage and not ossified yet. They often come out in weird shapes as they are cartilage, not bone - so they straighten out in a day or two.

Here's a baby that hatched from a more unusually oval egg just last week. The baby was inside the egg diagonally and had that shape when hatched. You can see virtually no seam separation at hatching, yet just a few days later the beginning of the seams spreading with new keratin growth. The tortoise's shell is almost entirely cartilage at this point. It takes a few years to fully ossify. It will ossify along the spine and at the bridge first.







Here is the same baby 3 days later...


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## CarolM (Apr 30, 2019)

Markw84 said:


> Inside an egg there is the shell, then an outer membrane. These are what you see when a hatchling breaks out of the egg. The inner membrane is sliced by the egg tooth and the movement of the legs. The pressure from within breaks the shell easily. The embryo and yolk sac is inside an inner membrane. The air sac is between that inner membrane and the outer membrane. So the embryo is separated from the air sac by that inner membrane and not in contact with the air in the air sac. The air in the air sac would be at 100% humidity as it is completely enclosed and the air transfer and water transfer in/out of the egg is at a molecular level.
> 
> I see no way the size of the air in the egg could effect pyramiding. Pyramiding is caused by the way the seams of the scutes grow over the underlying bone. There is no seam growth while in the egg, and the "bone" is cartilage and not ossified yet. They often come out in weird shapes as they are cartilage, not bone - so they straighten out in a day or two.
> 
> ...


Thank you Mark. And wow what a difference.


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