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New hatchling from a friend's collection

Discussion in 'Bowsprit tortoises' started by Sterant, Feb 13, 2018.

  1. Sterant

    Sterant Well-Known Member

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    A friend sent these pictures today - this hatchling came after he purchased a gravid female. She laid the egg soon after he acquired her, and hatched fine. I have asked for incubation temp/RH/time and will share once I have that information.

    27999990_1553050844731509_1160893571_o.jpg 28033544_1553050798064847_1389265300_o.jpg 28081071_1553050791398181_1676628444_o.jpg
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  2. Sterant

    Sterant Well-Known Member

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    Incubation was typical. RH at 75% +- 15% . Temp 82 degrees F. No night drop. 120 days.
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  3. CarolM

    CarolM Well-Known Member

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    Really beautiful.
  4. Tom

    Tom The Dog Trainer 5 Year Member

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    I hope to see something like here at my house one day.

    So just regular old hatching techniques, and the baby hatched right out… Hmmmm…. The plot thickens….
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  5. Maro2Bear

    Maro2Bear Well-Known Member

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    Very very cute perfect lil hatchling. Enjoy!
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  6. HermanniChris

    HermanniChris Well-Known Member TFO Sponsor 10 Year Member!

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    I'm banging my head against the wall reading this Dan....
    But, maybe what you e-mailed me last night sheds even more light....
    There's still hope here. 2 eggs going and more nesting taking place right now.
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  7. Sterant

    Sterant Well-Known Member

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    Yes - just typical incubation stuff. Also getting the baffled look when I ask how he got them to hatch. "What do you mean?...I put them in an incubator" ;-)
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  8. Sterant

    Sterant Well-Known Member

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    Agreed buddy.

    For everyone else's sake, I only have this in print form, but I typed it in. To give proper credit, this bit of research was performed by a researcher in South Africa whose work I have been following for a while, and it is all fantastic. Professor Margareth Hofmeyr. She often works with Ernst Baard which is how I was introduced to her work. Also Gerald Kuchling was involved with this one. It was most recently published in the December 2017 issue of African Herp News.

    Amazing discovery that Bowsprit tortoises can retain eggs internally, while the embryo is developing, and nest just prior to the hatchling emerging from the egg. Comments about the reduced thickness of the shell allowing for better oxygen diffusion in-utero got me thinking about egg thickness, calcium intake, and a few others things I was discussing with Chris.

    Here it is.....enjoy!

    Chersina angulata has an unusual reproductive pattern for a species experiencing pronounced temperature and rainfall seasonality. Females produce single- egg clutches from March to December and can lay up to six clutches per year. Egg retention in the uterus varies from 23 to 212 days and correlates with temperature and rainfall.

    Prolonged egg retention is considered the first step in a transition from oviparity to viviparity in reptiles, but females still need to overcome the constraints of full embryonic development in the uterus. Conventional wisdom holds that chelonians are strictly oviparous with embryo development in the mother being arrested in the gastrula stage, due to insufficient oxygen diffusion across the calcified eggshell in the wet uterine environment. We measured eggshell calcification of 16 captive C. angulata females over 12 months and found that more than 70% of the eggs had relatively thin eggshells at oviposition, a characteristic that would improve oxygen diffusion to developing embryos. We found evidence from the wild and captivity that C. angulata females can retain eggs until embryonic development has progressed to the hatching stage, conforming to the accepted definition of viviparity in reptiles. Hatching in C. angulata occurs in March to April at the start of the rainy season. Consequently, early clutches of this species incubate for 12 months whereas late clutches incubate for 3-4 months, the duration required for artificial incubation.

    Our observations of viviparity were of eggs laid in early autumn, indicating that instead of laying the eggs late in the previous year, the females carried developing embryos until hatching normally occurs for the species. We propose that facultative viviparity in angulate tortoises is limited to late-season clutches that do not undergo developmental arrest, and represent yet another reproductive strategy that ensures this species’ success.
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  9. CarolM

    CarolM Well-Known Member

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    Whahaha
  10. CarolM

    CarolM Well-Known Member

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    This is very interesting. Thank you, I enjoyed reading it very much.
  11. Tom

    Tom The Dog Trainer 5 Year Member

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    I've never heard anything like this in regards to any chelonian. I've never heard mention of this by any keeper either.

    Interesting too that the eggs in the wild hatch in Autumn which is the start of the rainy season (hydration), but also the start of the colder time of year.
  12. Sterant

    Sterant Well-Known Member

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    Got me thinking about calcium requirements for a small tortoise, that only lays one egg at a time, and produces thin-wall shells to aid in oxygen diffusion. What happens if the diet is too high in Calcium? Do the shells thicken thereby reducing available oxygen to the embryo? Would excess calcium be harmlessly passed through the system with no impact on the egg? I don't know...

    I am following up with Prof. Hofmeyr to see if additional research has been done in this area. As Dwight said to me, this is big news to be buried in the middle of an AHN.
  13. Sterant

    Sterant Well-Known Member

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    Can you imagine a tortoise laying an egg and it hatches 2 days later fully developed?
  14. Tom

    Tom The Dog Trainer 5 Year Member

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    That is a fascinating concept, and if that is a common thing for this species, I wonder why no keeper has ever mentioned this?
  15. Tom

    Tom The Dog Trainer 5 Year Member

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    There was a presentation done for an aquatic turtle species at TTPG last year. I believe it was one of the Podocnemus… @Markw84 please correct me if I'm wrong. Anyhow, the concept was that when this breeder incubated the eggs in long fibered peat moss, the acidic properties of the moss helped to dissolve the eggs shells over the course of incubation and made that calcium bio-available to the developing embryo/hatchling. This presenter had recorded higher hatch weights along with greater vigor and health compared to hatchling incubated on plain vermiculite or there media.

    Don't know if this would translate to tortoises, but its an experiment I'd like to try with a sulcata clutch. Half on peat moss and half "normal".
  16. Markw84

    Markw84 Well-Known Member 5 Year Member

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    Perhaps it is the conditions the female is being kept in that triggers this strategy or not. So in captivity, eggs are not retained. I have read several studies where some chelonians will have eggs go through diapause or no diapause depending upon the conditions the female is in the month or so prior to egg depostition.

    Yes, Dave Drajeske was talking about the use and need for calcium by the hatchling and how if the nest environment is correct, the eggshells will be thinner and the hatchlings much bigger. I have been communicating back and forth with Dave ever since the conference. There is really good studies with some snakes on exact portions up calcium left in eggshell vs. hatchling by exact measurement. Matamata eggs are so thick that if not incubated in a more acidic environment, they cannot hatch. Also lots of stuff on the water uptake ability of the medium used in incubation. He is working with P erythrocephala. If he does not use media wet enough, the eggs can't transfer the ionic calcium as well. Also studies are now seeming to point to the avialability of ionic calcium when the egg is laid as a factor is "setting" the embryo and early development.

    All these things seem to possible play into things this retained egg strategy may indeed be overcoming??
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  17. Sterant

    Sterant Well-Known Member

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    It would seem that this "feature" might never show up in captivity. I think in order for the tortoise to retain the egg in-utero for a long period, they would have to be exposed to the seasonal conditions that would prompt that behavior - and I don't know of anyone (especially in the US) that "leaves them out in the cold". Fascinating ability for sure. My head went where your did in that some method of increasing oxygen diffusion might help all of the incubation problems we see. I like the "acid etching" idea.
  18. Sterant

    Sterant Well-Known Member

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    All of this (at least to me) is a possible indicator of the problems we see in chersina where embryos develop for a while and then development stops. Perhaps as the embryo grows, its need for oxygen surpasses the shells ability to transmit it - thereby suffocating the developing embryo. Would a diet lacking calcium help? Some chemical etching help? Very interesting stuff.
  19. Markw84

    Markw84 Well-Known Member 5 Year Member

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    Seems to be a balance between enough moisture to allow proper transfer of calcium, yet not too much to block oxygen.

    Can't imagine diet would be a big factor. Metabolic function controls blood calcium level to stable levels no matter what diet is. Taking what it needs from the diet, or from the bones if diet is insufficient. However, anything blocking calcium/oxygen to inside the egg environment is a different function once the egg is laid. Both from the eggshell and possibly environment (moisture coming through calcium rich substrate the nest is dug in?) Some things block that calcium as possibly we see rinsing eggs in tap water with fluoride??? Or using water with very low alkalinity?? Something else we're looking at!
  20. Tom

    Tom The Dog Trainer 5 Year Member

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    This is exactly how Vince keeps them here in coastal San Diego. His climate is very similar to the SA Cape climate, perhaps a little warmer and sunnier more often even.

    He said the only time he uses any heat at all is when its going to drop below freezing for hatchlings. In that case he puts a 100 watt light bulb over them for the night. No heat at all for the adults or juveniles.

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