Vivipary
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A viviparous animal is an animal employing vivipary: the embryo develops inside the body of the mother, as opposed to outside in an egg (ovipary). The mother then gives live birth. The less developed form of vivipary is called ovoviviparity, which, for instance, occurs in most vipers. The more developed form of vivipary is called placental viviparity; mammals are the best example, but it has also evolved independently in other animals, such as in scorpions, some sharks, and in velvet worms. Viviparous offspring live independently and require an external food supply from birth. Certain lizards also employ this method such as the Genus Tiliqua and Corucia. The placenta is attached directly to the mother in these lizards which is called viviparous matrotrophy
Ovoviviparous animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch. This strategy of birth is known as ovoviviparity. It is similar to vivipary in that the embryo develops within the mother's body. Unlike the embryos of viviparous species, ovoviviparous embryos are nourished by the egg yolk rather than by the mother's body. However, the mother's body does provide gas exchange.
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