Carbon dioxide influence on eggs hatching?

[DragnDrop]

Has anyone heard of or known about carbon dioxide build-up being highly influential in eggs hatching? I was talking to a long time herper at the show last week and was told about this. It's the first time I'd heard it, but it makes complete sense to me. It sure could explain a lot of mishaps I've had over the years. Next breeding season I'm going to keep better records and see if it can explain any premature or non-hatching eggs I might have.

In short, carbon dioxide build-up helps initiate hatching in a lot of egg laying species, not just reptiles, but birds as well. The low oxygen causes the embryo to struggle and break the shell. It helps explain the mass hatching of entire clutches like chams too.

I'm going to be more careful how often I open the delicups next year when eggs are close to term, and making it a point to open the lids more often early during incubation. Off hand, I do know of 3 premature and 2 non-hatching geckos from this year alone that could have been 'victims' of this theory.

[Steeve B]

Hers the last post I did on the subject in reply to someone covering his eggs with saranwrap!


In a sealed container there will be carbon dioxide built-up! Especially in small containers, small containers for big varanids eggs are very unstable, it is much safer to use large and deep, the deeper the medium the more stable your humidity will be. Take for example a Ziploc sandwich container with an egg that fills 10% of the containers inner space, the developing egg will release carbon dioxide, this will in turn create movement drawing the water out of the medium and on to the walls and top forming droplets that will slide down to the bottom, its easy to understand that while this is happening your egg is dehydrating at a very rapid rate (denting), furthermore the limited and confined air space will allow for carbon dioxide built up, this again limiting the eggs ability to breath oxygen via water vapours. Mortality rate will be high, especially in full term embryo’s (anoxia) others will hatch and show sings of anoxia excessively large sacs! Brain damage! Or simply very week. However when egg containers are set in safe incubators, and the incubator is itself located in a heated room, egg containers can be opened routinely without any damages to the eggs. If you need to completely seal your eggs to avoid dehydration, your incubator and egg containers $ucks big time! :)

[Stockwell]

Hilde, I've never heard of that before, but it sounds like nonsense to me.
Since when does lack of oxygen cause increased muscle activity.
In a mammal with higher brain function, one might sense a respiration problem and run for the nearest door, but even that is a stretch and in humans it's more likely to cause lethargy, reduced brain an muscle function and eventually unconsciousness.
My feeling on this is the more oxygen the better. I'd think too much Co2 and not enough O2 is more likely going to prevent eggs from hatching rather than promote it.

[crocdoc]

2 clutches, 12 hatchlings (second clutch only shown below). 100% hatch rate (aside from one dud egg that deteriorated 2 weeks after laying). Incubation time from 186-205 days (clutch 1), 225-261 days (clutch 2, slightly lower temperature). All sealed in with SaranWrap.

http://mediaservice.photoisland.com/auction/Sep/20049241725034318564207.jpg.

261 days, that's a LONG time to be sealed in! The big secret? SaranWrap breathes. Keeps in humidity but allows gases to exchange. In other words, even if the whole CO2 thing were true (personally, I have my doubts that it hastens hatching), it has little to do with SaranWrap.

[CarlC]

I would be cautious if using this approach. Yes sure it might help the baby to break from the shell but a healthy baby should not have this problem.
Oxygen in my opinion is more important. I would think that in the wild each time it rains or in loose substrates the exchange rate is good. Each time it rains the water would bring a fresh supply of oxygen.
I have always thought that the biggest problem with Chameleons atleast is the anxious keeper. Opening the hatching box each time a baby hatch's. Once the box is opened the warm humid air is lost. After this happens the fine balance needed for hatching is lost. It does not hurt to leave the newly hatched baby in the container for a couple of days. If the baby had a healthy mom the yolk absorbd will sustain the baby for a few days.
Concernign the mass hatching of Chams- I think this is more related to vibration. It would make more sense for the majority of babies to hatch when it would be easier to dig through the hardend ground with the help of the others.

Just some thoughts!
Carl

[DragnDrop]

I've done some research on the CO2 influence on hatching, so far only found it in reference to bird eggs. It seems to be well documented for them, but I can't seem to find anything about reptiles, except for one short paragraph in a book. Since reptiles are closely related, I thought it might be the same with them (for some species at least).


Two examples of CO2 and bird eggs that show the relationship:

Exotic Pet Vet (http://www.exoticpetvet.net/avian/incubation.html)

The initiation of hatch occurs partially from the increased carbon dioxide level in the egg.
This causes the embryo to begin twitching it's muscles, allowing the inner shell membrane to be
punctured by the egg tooth. The chick then begins breathing the air in the air cell. As the
carbon dioxide level begins to rise again, the muscularia complexus (the pipping muscle) at the
base of the neck begins twitching again, facilitating the hatch. Abdominal muscles also begin
twitching, which helps draw the yolk sac into the celoem. Leg muscle twitching helps strengthen
the legs.


Chickscope - Univ. of Illinois (http://chickscope.beckman.uiuc.edu/explore/embryology/day15/dev.html)

The amount of oxygen supplied through the eggshell is adequate until the chick starts the exhausting process of hatching. During incubation, the water lost by the egg through evaporation is replaced by air, which is stored in the air cell. By the time the chick begins hatching movements, the air cell has grown to fill 15% of the egg. The chick's first hatching movements are to break the shell membranes covering the air cell and take its first breaths with its lungs. The extra oxygen stored in the air cell is enough to allow the chick to break through the eggshell. Even with the air cell ruptured, there is still a high concentration of carbon dioxide in the egg compared to the outside environment. The high concentration of carbon dioxide actually causes the neck muscles of the chick to jerk and thus allows the chick to peck through the eggshell.



I'm still looking for reptile egg references, but might have to switch to the much slower search - printed books. ;)

[crocdoc]

Here's the problem with comparing birds to reptiles: birds have an air space in the egg, reptiles don't. Both of those articles refer to a buildup of CO2 in the egg rather than in the egg's outer environment. They also refer to the buildup occuring after the bird has started working on the shell. In reptiles there is no air space. The first breath occurs when the shell has been slit and the hatchling 'pips', sticking its nose out to breathe, rather than inside the egg.

[CarlC]

Another thing to consider with Chameleons are the species that give live birth. The times I have seen babies born with live bearers no egg tooth was visible. When the egg sac hit the ground or branch's on the way down the baby was stimulated by the impact or hitting branch's on the way down. Egg sacs that did not drop took much longer to show any movement by the baby. In my experiance this is usually where I find the highest mortality with live births. The egg sac dries before the baby starts moving or the baby is able to break through but the drying sac adheres to the face and the baby is not able to remove it.

Carl

[jadegrasse]

Gator eggs are baried in rotting bio mass with almost no O2 and they hatch fine. I seal all my rat snake eggs in Tupperware containers with a few small holes in the lid. I open the containers every other day and my success rate for the past 5 years is almost always 100%. This year we hatched over 140 corns.