Reptile & Amphibian Forums

In watching crocodile shows and whatnot, they mark the top of the eggs to be certain that they don't incubate them on the wrong side. It seems to me that unless the eggs are designed in such a way that even though they are dropped in water, they still end up setting correctly...it seems that by them laying in water it somewhat puts his hatchling at risk.

Anybody have any further information regarding crocodilian birth?

Thanks,

Chris
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Chris Law
U.A.P.P.E.A.L. (Uniting a Proactive Primate and Exotic Animal League)
Herpetoculture Element Representative

Hey Chris,

Unless I'm reading this incorrectly, eggs laid in water if fertile cannot survive, but drown. I think if I provided the correct substrate she would have dug a cavity and set the eggs.

Why she laid in the water and not on the carpeting, who knows. But eggs in the water would never survive.

These eggs are super strong - It took about 3 or 4 2 foot drops on the concrete floor to crack an egg. Really cool, I had to freeze a couple.

Rob

I have heard of instances where first time Mothers have laid their eggs inappropriately. The thing that I am curious about, is how do the eggs get air? It seems that eggs of different animals are quite amazing as to how they get air inside the egg.

Regardless, I am curious about how the eggs will die if they are not kept in a certain position. Can anyone add any insight to this?

Thanks,

chris
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Chris Law
U.A.P.P.E.A.L. (Uniting a Proactive Primate and Exotic Animal League)
Herpetoculture Element Representative

There are a number of components that make up the biology of the egg. Besides the yoke, there is something that functions to exchange gasses and something that functions as a cushion to asbsorb shock. In the first 24 hours the embryo attaches to the top of the yoke. If the egg is turned once the embryo has attached itself, the yoke will be on top of it, drowning the embryo. From what I remember, it takes 15 or 20 days for the part (I can't remember the name of it) to develop enough to perform the gas exchange. Once that happens, the egg can be turned without killing it.
There is a pretty good section on it in one of my books, but I can't remember which one and I'm too lazy tonight to look.

Bill

Well not exactly. Egg orientation is a little bit of a myth. Most people will keep the eggs facing the same direction but eggs are pretty resilient. The eggs cannot be rolled but the orientation can be changed so long as it is done with care.

Think easy gentle manipulation.
The Ultimate Guide to Crocs

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CDieter
'Reason, observation, and experience; the holy trinity of science.'

Of course, where I am, I don't have access to actual egg harvesting so I rely on the studies of others. Here is what I found in a quick perusal of my literature.

From Handbook of Crocodiles and Alligators by Grenard, page 26:

According to Ferguson (1985), it is irrelevant which way crocodilian eggs are laid because the embryos within always wind up oriented atop the upper surface of the yolk which is where they should be to develop normally. If a crocodilian egg is turned after the embryo has attached itself to the yolk while still young (2nd to 10th day), the embryo remains attached to the yolk but now is beneath rather than atop it. It will drown in the yolk and die. Studies by Webb et al. (1987) indicate that rotation of crocodilian eggs occurring after the first 24 hours but before respiratory and excretory functions of the chorion and allantois are adeqately developed (about the 13th day) will result in embryonic death. Rotation of older eggs (15+days) appears to be safe. The critical period when eggs should not be handled or rotated appears to be between days 1 and 15.

The chorion was defined as a structure that acts as a lung enabling some gas exchange and the allantois receives metabolic wastes.

Bill

Point well taken, but I think we may end up talking around each other a little. I hope my coauthor doesn't get upset with me but I think this paragraph from my coauthors section can shed some light on this discussion. A brief preview:

The myth of egg orientation – It is standard practice to avoid rolling crocodilian eggs to prevent killing the embryo. However there is a fairly common misconception that eggs must always face the same direction once laid, with some keepers going to extreme lengths to transport eggs without so much as changing their angle! This is simply not necessary. It is true that eggs cannot be rolled, but there is nothing preventing their orientation from being changed as long as it is done gently.

I personally have always tried to keep them upwards and in the past have been paranoid above turning them. But on eggs that had been turned gently, either purposely or accidentally, I never witnessed any developmental problems. But I haven't worked with 1000's of eggs either.

Good discussion Bill.
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CDieter
'Reason, observation, and experience; the holy trinity of science.'

Gentlemen,

Perhaps I am misreading your posts, but it appears that their is actually agreement between you. There seems to be confusion over the definitions of the terms "roll" "rotate" and "turn."

I am differentiating rolling from turning, the former being a complete top-to-bottom reorientation (which, of course, may drown the embryo at certain stages), the latter being a simple lateral one.

What say you?
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Israel Dupont
Winter Haven, FL

Thats what I said, I think we are talking past each other.

Hey Israel, on a side note. I missed seeing your email until this morning. Expect mail in the next few days.
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CDieter
'Reason, observation, and experience; the holy trinity of science.'

I think anytime we can converse about croc biology it's great. This is probably the aspect of crocodilians that interests me most, and that we discuss the least here.

Bill

N/P