10 Ridiculously Weird Animal Mating Rituals
2. Female Cats Can Get Pregnant While Already Pregnant
Unlike most mammals, when a female cat becomes pregnant its body sometimes continues to produce eggs. The result is that bizarrely, should a female cat engage in mating behaviour when it is already pregnant, it can become pregnant again with completely different litter of offspring, sometimes even with a different father to the original pregnancy.
The offspring from the second pregnancy often tend to be born at the same time as the first litter which (assuming they survive being born too early) can lead to the strange situation where the kittens are different ages despite being born at the same time.