Reptile & Amphibian Forums

hey lets continue the Thread here. I cant believe so many people feel differently on the topic.....I didnt think it would be much of a debate about it. I thought maybe there was a simple one way answer. Maybe we can Find out if we keep looking.

Anyone have the book: The Garter Snakes: Evolution and Ecology (Animal Natural History Series, Vol 2)
by Douglas A. Rossman

and could take a look here to find out?? I hear that this book is one of the best out there on Garters. It should have a solid answer on this matter if not something we can all agree with.

But Damn this is a good topic and everyone should how they are really consieved. (sp??)

Lu

Ok... I don't know about other snakes but mine (florida blues) are NOT placental... I have bred gerbils and I know what a plcenta looks like. I mean unless the EGGS are attached to a placenta like thing ... in which case she would birth thouse as well (like the gerbils did) ...

How can I be so sure? First, parden me I'm a bit upset (still though its two days later) .

She started giveing birth at 4:00 on the 4th. I went into my bedroom to get some socks because I was leaving to go to my parents. She had two invertal eggs (slugs/look like orange jellybeans) allready out and I was thinking oh no.

WELL... After dining at my parents ... watching my brother race a stock car and watching fireworks... I got home at 11:30 knowing I'd still have to look for babies.
She had 17 infertaile eggs and 3 what I thought was still births.

Until one moved.
I thought I was imaginaing it. It was wet and soft as oppsed to the others which were dry. I watched it for a bit ... layed it on the counter of my bathroom. Defenatly alive... definatly moveing. I was like... "oh God what do I do?" (and yes btw that would be a real prayer) The only thing I really could do was cut it out... of the clear membrae/egg sac it was incased in!
Oh and btw it had a blob of yellow by its head... can you say... "egg yoke" it was oviously premature. SO I cut the area CAREFULLY with a little pocketknife and got the head free where it opened and closed its mouth several thimes.
The covering was thicker then it looked and I had to peal it compleately off for it to move. There were little vains here and there as well... and NOTHING that looked like a placenta or that was directly connected to the snakeling.

Unfortantly it didn't survive... eather dieing before I was done or right after. It looked a bit deforemed as well ... but I HAD TO TRY.
At any rate any more argueing on the subject at this point will seriously piss me off so I hope people drop it.
Because I don't care what the books say I know what I observed UP CLOSE AND PERSONAL.

BTW The book I read when I was a kid that said we only dream in black and white was wrong too.

- Sharon

I'll look into this more, because it's going to drive me crazy.
From what I understand, and I'm not POSITIVE, because I haven't researched it before this debate, is that viviparous reptiles give live birth, and there is SOME basic placental transferrence between the mother and offspring. The difference between retaining eggs and having them hatch inside the mothers body and having a placental structure is that the fetuses do not receive ANY additional support from the mother in egg retention. Garter snakes have a rudimantary placental structure in addition to being encased within a caul-type egg structure within the parents body. This is what I've gotten from looking it over in the past few days. To be honest, I have no clue, and haven't looked into it deeply enough to argue the point one way or another. Now, I will...Grrrr.....

Thamnophis Ordinoides or NW Garter Snake is viviparous.
Oviparous = Fetuses develop in eggs outside the body.
Ovoviviparous = Fetuses develop inside the body, in eggs, without any support from the mothers systems.
Viviparous = Fetuses develop inside the mothers body with support from her systems. (supplemental to a yolk sac in this and other cases [See sharks])

Stewart, J.R., D.G. Blackburn, D.C. Baxter, and L.H. Hoffman (1990). Nutritional provision to the embryos in Thamnophis ordinoides (Squamata: Colubridae), a predominantly lecithotrophic placental reptile. Physiological Zoology 63: 722-734.
Abstract: Quantitative analysis of the composition of eggs and their sibling neonates in the viviparous natricine snake Thamnophis ordinoides revealed that yolk provided the principal source of organic nutrition but that embryos received a substantial allotment of inorganic nutrients from the placentas. The placental provision of water and sodium equaled or exceeded yolk supplies, and placental transport accounted for 23% of neonatal calcium composition. There was no difference between egg and newborn quantities of total phosphorus or total potassium., whereas neonates contained less total magnesium than eggs. The mode of embryonic nutrition in this species is characterized as predominantly lecithotrophic, yet placental nutrient provision contributes significantly to embryonic nourishment. Placental transport of sodium and embryonic uptake of water was greater in recently ovulated eggs that contained relatively low levels of sodium and water respectively. thus, placental sources compensated for low yolk provision. Placental transport of calcium was independent of yolk calcium content and correlated positively with neonatal calcium content. This pattern of provision, in which placental sources determine neonatal content independent of egg content, has been described as facultative placentotrophy. A similar embryonic nutritional pattern was recognized previously in another predominantly lecithotrophic natricine snake.

I really dont know what to think now about it. Many ppl agree that they are vivaparous and many agree that they are ovioparous.

I will be doing some research on it to, but I think to many ppl disagree with each other to come to a final answer.

Lu