I was driving my daughter to work this morning and she was in the back seat reading a book called “Too Many Puppies.” It triggered a question that I’d appreciate the answer to:
Humans females usually release only one egg at a time, as do (I’m assuming) other animals that typically give birth to only one newborn at a time. Do female animals that normally give birth to multiple offspring (dogs, cats, etc.) release the same number of eggs each cycle?
There’s a lot of difference for various animals, but in the case of dogs and cats, I believe that the number of ova released on an estrus cycle can vary for a given individual. As evidenced by the fact that a bitch can have different litter sizes from one to another. Of course, that COULD just indicate that some of a constant number of ova fail to get fertilized, but I seriously doubt it. In fact, it’s generally claimed that a bitch’s litter sizes generally tend to decrease as she ages, consistent with her releasing fewer ova.
As I said, it’s going to differ a lot from animal to animal. Bears usually have two cubs, though it can vary from one to four. Anything other than two is probably to be considered an unusual occurrence, like twins in humans. I’m going to WAG that one would probably indicate that a released ova failed in most cases.
You also have to ask about released ova splitting after fertilization. Armadillos, for instance, nearly always give birth to identical quadruplets.
Y’know, that’s a really good question. I don’t know why I didn’t think of it before.
I mean, I raise rats, and my females have had from 6-15 babies at once, depending on diet. Do they release more eggs depending on nutrition, maybe? Like, depending on how much protein there is?
I also raise Ball Pythons, who have anywhere from 3-9 eggs. Same diet, same weight. Well, since we’re talking live births, you could talk about boas, but I guess you’re talking mammals.
Trivia: A female snake can hold sperm in her body for years, until conditons are right. One Anaconda (I forget if she was yellow or green) gave birth something like 20 years after being brought into a zoo and being kept alone. Neat.
I’ve always wondered this- how does the animal keep the sperm in her body alive? Does she have some way to ‘incubate’ it? I’ve heard Queen bees do this as well- they mate once and they have all the sperm they need in a lifetime.
How does the snake fertilize their eggs? do the eggs pass through a chamber where the sperm is held, or what?