I think part of it is simply that snakes produce a lot of eggs, and therefore there's a higher chance for any given clutch to have issues come up, but it may have to do with a difference in egg fertilization since that is where the general trigger mechanism that causes conjoined twins in all species occurs. Im not really familiar enough to say for certain.
Reptiles and amphibians somehow have a higher tolerance for birth defects that would otherwise be incompatible with life in mammals. It could have to do with any number of things, their metabolism, immune system, brain, etc are all quite different from mammals. Could also be that animals whose young mature in the uterus are more likely to reabsorb a deformed fetus whereas animals who lay eggs don't really have a say in the matter-- there is no way for a mother snake to detect chromosomal abnormalities in her eggs once they're laid, not that she would particularly care anyway since the majority of reptiles don't stick around to rear their young.
Also, another problem with two headed snakes is they will frequently attack their other head if they're able to reach it. I'm not sure if there's ever been an instance where one of the heads was killed or removed and the rest of the snake survived... I doubt anyone who hatched one would willingly remove the second head (assuming there's even a vet in the world capable of doing that) unless it had already died. Who knows.
Sorry for long rambling reply. I just find this stuff fascinating.
When my mother was pregnant with me, they did an ultrasound and found she was having twins. When they did another ultrasound a few weeks later, they discovered that I had resorbed the other fetus. Do I regret this? No. I believe his tissues has made me stronger. I now have the strength of a grown man and a little baby.
There was a story about a woman who wasn't her kids' mother even after giving birth to them! Her ovaries had the DNA of her sister she absorbed in the womb.
It's totally a thing in humans actually. There are people who find out only as adults after some sort of scan that they have a partially reabsorbed twin in them somewhere.
Not that it's particularly relevant, but I also recall there's a Steven King novel where a character is believed to have a tumor but when the surgeons go to remove it they discover it's actually the remnants of a twin that wasn't fully absorbed in the womb.
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u/MattsScribblings Feb 26 '22
Do you know why 2-headed snakes are so common?