Viviparity and ovoviviparity are two reproductive strategies observed in various animals. Viviparity refers to live birth, where embryos develop inside the mother and receive nutrients directly from her, as seen in most mammals. In contrast, ovoviviparity involves eggs hatching inside the female's body, leading to the live birth of fully developed young, without direct maternal nourishment during development, commonly found in some reptiles and sharks. Both strategies enhance the survival of offspring in different environmental contexts.