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Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (known as laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings known as hatchlings with little or no embryonic development within the mother.
Among mammals, the monotremes are oviparous. Ovo-viviparity: or oviparity with retention of zygotes in either the female's or in the male's body, but there are no trophic interactions between zygote and parents. [1] This mode is found in the slowworm, Anguis fragilis. In the sea horse, zygotes are retained in the male's ventral "marsupium".
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop inside eggs that remain in the mother's body until they are ready to hatch.
[16] [17] The presence of vitellogenin genes (a protein necessary for egg yolk formation) is shared with birds; the presence of this symplesiomorphy suggests that the common ancestor of monotremes, marsupials, and placentals was oviparous, and that this trait was retained in monotremes but lost in all other extant mammal groups.
Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possibly by brooding and hatching the egg.
Pythons are oviparous, laying eggs that females incubate until they hatch. They possess premaxillary teeth, with the exception of adults in the Australian genus Aspidites . [ 3 ] [ 4 ] While many species are available in the exotic pet trade, caution is needed with larger species due to potential danger.
Animals are commonly classified by their manner of reproduction, at the most general level distinguishing egg-laying (Latin. oviparous) from live-bearing (Latin. viviparous). These classifications are divided into more detail according to the development that occurs before the offspring are expelled from the adult's body. Traditionally: [24]
The divergence between oviparous (egg-laying) and viviparous (offspring develop internally) mammals is believed to date to the Triassic period. [31] Most findings from genetics studies (especially of nuclear genes) are in agreement with the paleontological dating, but some other evidence, like mitochondrial DNA, give slightly different dates. [32]