vivípara

Vivípara, or viviparity, is a mode of reproduction in which embryos develop inside the parent and are born as live offspring. This contrasts with oviparity, where eggs are laid and hatched outside the body, and with ovoviviparity, where eggs hatch inside the mother but nourishment comes primarily from the yolk rather than the mother’s tissues.

In true viviparity, the developing embryo receives sustained nutrition from the mother through structures such as a placenta or through uterine secretions, enabling longer gestation periods. This can involve intricate physiological adaptations, including forms of placental transfer, histotrophy (nutrient transfer via uterine fluids), or other maternal–embryo connections. Some groups display placental or placental-like provision, while others rely on yolk and maternal tissues to varying degrees.

Viviparity has evolved independently in multiple animal lineages, including mammals (where it is the dominant mode), as well as certain fishes, reptiles, and some invertebrates. In these lineages, reproductive strategies range from highly extended gestation with prolonged parental care to shorter pregnancies with less postnatal investment. The evolution of viviparity is often associated with environmental pressures such as predation, climate, or resource availability, enabling embryos to develop in protec­tion within the mother’s body.

The term derives from Latin roots meaning “alive” and “to bear.” In everyday usage, vivípara emphasizes live birth as opposed to egg-laying, highlighting a major divergence in reproductive biology across the animal kingdom.