Meaning of viviparous animals
What are Viviparous Animals:
Viviparous animals are those that are born inside the pregnant parent, unlike oviparous animals that are born from eggs incubated outside.
Viviparous animals gestate in the female's placenta, through which they receive all the oxygen and nutrients they require to develop and be born.
In most cases, viviparous females give birth to fully developed young, or at least, in an advanced stage of growth, ready to grow autonomously.
Types of viviparous reproduction
According to the type of development of the future offspring, viviparous animals are classified into three types.
They are those that develop in specialized structures within the female's womb, such as the human placenta, which adapts to the fetus and widens so that it can achieve optimal development.
Other placental viviparous animals would be dogs, cats, cows, horses, chimpanzees and elephants, among others.
Placental viviparity is considered a more evolved gestation system than oviparous (gestation through eggs), since the offspring remain protected from external threats within the mother's womb, giving them greater opportunities to survive.
In this case, the offspring do not complete their development inside the female's womb, but in external structures that fulfill a function similar to the placenta so that they finish forming. The classic example is kangaroos.
In addition to kangaroos, koalas, opossums, and the Tasmanian devil are also viviparous marsupials.
Here, gestation takes place inside an egg, but this remains inside the female's body until the end of its growth phase. The egg can hatch inside or outside the mother's body. The constrictor constrictor it reproduces through eggs that remain inside the mother until hatching.
Anacondas, Surinam toad, stingrays, platypus, and seahorse are some species of ovoviviparous animals. In the case of seahorses, it is the males that carry the eggs inside.
Characteristics of viviparous animals
- In viviparous animals, fertilization takes place internally after the male's sperm fuses with the female's ovum, forming the zygote.
- The young develop in specialized structures located in the female's womb until the moment of birth, when they go outside through childbirth.
- Gestation time and number of offspring varies by species. In humans, for example, gestation lasts 9 months, and the most common is that a single embryo develops. Cases of multiple gestations do not occur frequently. In dogs, gestation lasts between 58 and 68 days and an average litter can have between four and six pups.