What is viviparous?

From the Latin vivipărus, viviparous is an adjective that allows mentioning the female that gives birth to her young in the phase of well-developed fetuses. That is, a viviparous animal is one whose embryo develops in the uterus, in a special structure that allows it to receive the food and oxygen necessary to grow until the moment of birth.

Viviparism can take different forms. There are viviparous animals without a placenta, such as marsupials. In these cases, the fetus is born premature, so it must continue its development in an external pouch. Placental viviparism, however, is most common within mammals.

Regarding the gestation period, it is important to determine that each species of viviparous animal meets certain deadlines. So, for example, in the case of the human being it is nine months, in the case of the bear seven months and in the case of the lioness it is only three months. Likewise, the number of offspring generated at each birth also varies remarkably. In women, it is common for it to be a single baby, although, of course, there are exceptions. But of course it has nothing to do with what happens to rabbits that can have twelve at a time or even dogs and cats that can give birth to seven puppies. Plants can also be viviparous, when their seeds germinate before separating from the parent plant. Viviparous animals can be contrasted with oviparous and ovoviviparous animals. Oviparous reproduce by laying eggs in the external environment. The fetus completes its development in this egg until the moment of hatching. Many animals can serve as a clear example of what oviparous animals are. Thus, among them we can highlight the chicken, the turtle, the crocodile, the ostrich… Among the oviparous, the presence of a unique species should be highlighted. They are monotremes that have the particularity of being the only mammals belonging to the oviparous category. In New Guinea, Australia or Tasmania, they managed to survive. Finally, the ovoviviparous are the animals that shelter their eggs until hatching, which can occur immediately after laying or at another time. Among the ovoviviparous animals we can highlight some such as certain reptiles, fish and also two known species that arouse great interest: sharks and snakes, as would be the case of the viper. However, within these last two groups there are also cases of oviparous and viviparous. It is important to note that certain characteristics are shared by all three forms of reproduction. For example, in oviparism and oviviparism, embryo nutrition will be determined by egg reserves. Viviparous and ovoviviparous, on the other hand, share the development of the embryo in the mother’s body.

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