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; placental mammals are the best example, but other animals have also adapted by incorporating this behavior, such as in scorpions, some sharks, some… (More on Vivipary)