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With more scientific rigor, five modes of reproduction can be differentiated [1] based on relations between zygote and parents:

  • Ovuliparity : fecundation is external (in arthropods and fishes, most of frogs)
  • Hemotrophic viviparity : nutriments are provided by the female, often through placenta. In the frog Gastrotheca ovifera, embryos are fed by the mother through specialized gills. The lizard Pseudomoia pagenstecheri and most of mammals exhibit a hemotrophic viviparity.

Land-dwelling animals that lay eggs, often protected by a shell, such as reptiles and insects, do so after having completed the process of internal fertilization. Water-dwelling animals, such as fish and amphibians, lay their eggs before fertilization, and the male lays its sperm on top of the newly laid eggs in a process called external fertilization.

Almost all non-oviparous fish, amphibians and reptiles are ovoviviparous, i.e. the eggs are hatched inside the mother's body (or, in case of the sea horse inside the father's). The true opposite of oviparity is placental viviparity, employed by almost all mammals (the exceptions being marsupials and monotremes).

There are only five known species of oviparous mammals: four species of Echidna and the Platypus.

See alsoEdit



External linksEdit

bg:Яйценосни животни

cs:Vejcorodost de:Oviparie es:Oviparidad eo:Ovodemeto fr:Oviparité gl:Ovíparo hi:अण्डजता hr:Oviparnostka:კვერცხმბადობა mk:Овипарни животниnn:Oviparpt:Oviparidade ru:Кладка яиц simple:Oviparous sr:Овипарија fi:Ovipaarinen sv:Ovipari te:అండోత్పాదకాలు uk:Яйцекладні тварини zh:卵生动物 --

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