Vivipary

Vivipary refers to a form of reproduction where the embryo develops inside the parent organism, eventually being born or released as a live offspring, rather than hatching from an egg or developing from a seed outside the parent. The term can be applied across various biological kingdoms, including both plants and animals, though the specifics of its manifestation differ.

In animals, vivipary generally signifies the development of the embryo within the mother's body, nourished directly by the mother through a placenta or similar structure. This is in contrast to oviparity, where the eggs are laid and develop externally, and ovoviviparity, where eggs develop internally but receive no direct maternal nourishment, instead relying on yolk reserves. Mammals, with the exception of monotremes, are primarily viviparous. Some reptiles, amphibians, fish, and invertebrates also exhibit viviparity. The adaptive advantages of viviparity in animals often include increased offspring survival rates due to protection from environmental hazards and predators, as well as enhanced resource provisioning during development.

In plants, vivipary describes several related phenomena. It can refer to the premature germination of seeds or embryos while still attached to the parent plant. This is most commonly seen in mangrove species adapted to saline environments, where seedlings develop on the parent tree until they are large enough to establish themselves in the intertidal mudflats. These propagules then detach and fall, hopefully taking root in a suitable location. Another form of vivipary in plants is the replacement of flowers with bulbils or plantlets along the inflorescence. These plantlets are essentially clones of the parent plant and can detach and root to form new individuals. Plant vivipary is often an adaptation to environments where seed germination is difficult or unreliable.