Oviparity

As oviparous (Latin oviparus, eigeboren ') refers to animals that lay eggs.

In the real oviparity is a reproductive form, are stored in the fertilized eggs. In order for this to come about, internal fertilization through copulation or by the inclusion of a spermatophore is necessary. The embryo is nourished during its entire embryogenesis ( embryonic ) from data stored in the egg yolk. Has the young animal after oviposition reached a certain size and thus a certain stage of development, it slips out.

Oviparous are the birds, most reptiles, including the dinosaur and other dinosaur, and the vast majority of salamanders, arthropods and worms. The only oviparous mammals are the monotremes to which the platypus and the echidna are.

Ovuliparie (of ovulation - as unfertilized ova formation ) occurs when unfertilized eggs are laid, which are fertilized only outside the mother's body, so by external fertilization. Ovulipar most bony fish and most of the Anura.

To be distinguished is the oviparity of the viviparous. Animals in which the embryo grows in the womb and not " slip " generally outside the mother's body, are viviparous or ovoviviparous. True viviparity exists only if the supply of the embryo via the metabolism of the mother, often through a placenta. Here is then spoken of placental viviparity.

A special form of oviparity or a transitional form between oviparity and viviparity is the Ovoviviparie. In this case, the egg remains in the womb. Where the embryo is supplied by the yolk contained in the egg. The pups can then either slip in the womb or shortly after oviposition. Ovoviviparous animals incubate their eggs so from inside the body. These are often referred to somewhat inaccurately as viviparous. Among them, for example, include most sea snakes, many sharks and other cartilaginous fishes, a few bony fish, some spiders and aphids.

Swell

  • Erwin Hentschel, Günther Wagner Zoological Dictionary, Gustav Fischer Verlag, Jena, 1990, ISBN 3-334-00348-5 4th edition.
  • Adolf Remane, Volker Storch, Ulrich Welsch: Short Textbook of Zoology, Stuttgart and New York: Fischer, 1989.6. Edition. ISBN 3-334-00333-7
  • Hans -Günter Petzold: tasks and problems in the study of the expression of life in the Low amniotes. MILU 5 (4/ 5): 485-786 ( Berlin Tierpark Book 38)
  • Zoology
  • Reproduction
628135
de