Oviparity is a mode of reproduction in which young, developed in fertilized eggs, laid outside the mother's body. This mode of reproduction is found in most reptiles and all birds. Viviparity means that their young develop inside the mother's body and are born alive. This is the mode of most mammals. Ovoviviparity is similar to viviparity in that there is internal fertilization and the young ones are born alive but differ in that there is no placental connection, the young are fed by egg yolk. This is found in seahorses, for example.
