Reptile & Amphibian Forums

I've seen split and/or extra scutes on turtles/tortoises hatched in captivity as well as in the wild. There are probably multiple variables that cause split or extra scutes, but I'd like to hear your ideas.

To date, I've heard possible causes may include:
- Disturbing eggs during incubation, (specific phase of development)
- Genetics
- Incubation moisture or humidity levels

Other factors I can think of thinking about include:
- Health/diet/hydration of the egg laying female
- Natural occurrence just seen more often in captivity
- Incubation substrate / contamination
- Oxygen or CO2 levels during incubation
- Eggs buried vs not
- Lack of day/night temp cycles during captive incubation
- Increased probability for specific species

The Reptilian Incubation book recently posted on this forum might have some insight but I haven't bought it yet. If anyone knows or related research or has an opinion, please share.
Thanks,
John

I am going to go with:
Incubation moisture or humidity levels

I had two hatchlings of mine that came out with irregular scutes and the vermiculite was dryer than the others. The humidity level was also lower overall.
Since I have increased the moisture and humidity slightly, I have not had the problem.

At first I thought it could be too much heat under the coils of the hovabator, but when feeling the vermiculite, I believe that is what caused it. I was incubating at 86 degrees with probe in the area of the egg also.

Just my experience so far.

Lori

There is no doubt that temperature is a primary factor for malformed scutes. Excessively high temperatures increase the incidences of split, multiple or malformed scutes.

Genetics also plays a part in some instances but temperature is the main cause.
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Ed
Tortoise_Keepers-subscribe@yahoogroups.com
Trying to keep the fun in Chelonian care

"Excessively high temperatures increase the incidences of split, multiple or malformed scutes."

I'm glad to hear it is a controllable variable. I hope your right.

Ed,
I do different temps for different species and/or desired sex.
What do you consider "excessively high"? >92F 33C, >95F 35C?
Provide general norms if your example is species specific.
Thank you,
John

There is one good study on tortoises and that is for Hermans. It was determined that the crossover temperature for males to females is 86 F. Now that's the temperature where you (theoreticaly) get 50% males and females. One day people will realize that biology is not that exact.

Now, that is with Hermans. My common sense tells me that not all species in all the different regions follow the same 'rules'. There is a good book on egg incubation and it appears that there is another to follow. It covers the 'crossover' temperature pretty well. with reptiles in general that temperature seems to be variable AND the crossover is sometimes female to male AND it sometimes crosses over back.

Simple, huh? I don't think so.

I'm sorry but I can't provide 'general norms' outside of the 86 F that I and many others use. Temperatures over 30 to 31 C usually result in abnormalities. My incubator is designed to vary between 29 to 31 C because I really don't know. If you read through whatever litterature that is available most others don't know either.

I hope this helps.
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Ed
Tortoise_Keepers-subscribe@yahoogroups.com
Trying to keep the fun in Chelonian care

hey tort fans,

the study illustrating that excessively high temps cause abnormalities was an outlier and probably shouldn't be extrapolated to all temperature ranges. there were other more severe deformities in the hatchlings from that study besides extra and split scutes.

if we were to incubate eggs at reasonable temperatures (28-31.5 C. for russian tortoises), barring any oops factors ("i forgot to close the shades and the sun hit the incubator and sent the temp through the roof"), and the temperature influence was real, wouldn't we expect to see a correlation between higher incubator temps and frequency of shell anomalies? further, shouldn't we also see a higher frequency of shell anomalies in females? i think, yes, we should expect to see these correlations.

after seven years and over 60 hatchlings incubated in carefully controlled incubators at several different temperatures, neither of these predictions pan out. in fact, the frequency of shell anomalies is significantly higher in males. i also see more shell anomalies in adult WC males than in females (anecdotal, but it holds for my adults as well).

so i agree, abnormally high temps will cause all kinds of morphological problems, including extra and split scutes. however, i think that the temperature effect falls apart when we're talking about normal range incubation temperatures, and that within normal range there are most likely other factors involved.

i suppose once these types of things are etched in stone, it's hard to make them leave the lore.

cool discussion.

matt

I agree, I don't believe only high temps are the cause. Since when I did incubate the two I had at 86 degrees and those two only out of 6 total(the two were in separate containers) came out with extra scutes...it leads me to believe that heat alone isn't the issue. There are other factors that can cause this as well.
On those two only, they were in a container by themselves and the vermiculite was dryer than the rest....actally very dry.

Lori

mrand you nailed it.BUT there is another factor no one mentioned.The carapace scutes are being formed in the early stages.Are we moving and picking up eggs along the way,I think so.Also how about when someone bumpted your incubator.OR how about that loud music you play with those heavy base woffers,theres none of that in the wild.I have pondered this for years and hatched a lot of Manouria eggs and some pairs pass on perfect and others have a faily consistant amount of carapace irragular scute formation.Wild borns that have it will pass it on even if the mate is perfect.Its genetics if were talkin abbarent.Deformation is temp related.Humidity is write or dead.It is so common in nature that taxon spliting or discription is never based on carapace scutes.The main problem with split or extra scute tortoises is their harder to sell,tortoise people want perfect scutes,unlike snake people who will pay much more for imperfect formation.I have a zig-zag mt. tort for an fortune if your instrested. Vic

Throw alligator eggs in your incubator set for "females".. (higher temps).. and guess what?? You get male alleys.. that's what I've been told.

You gotta love 'em!

Terry

...one incubator...two incubators...why not 3...so you can have it both (or multiple) ways...that is if you have enough eggs to play with