Egg breeding is a way of reproducing offspring in animals , combining signs of live birth and egg production . When it is, the female animal does not lay eggs or caviar , but carries them within itself. The cubs leave the egg membrane in the mother’s body and are then born.
The main difference between ovovivipating animals and placental viviparous is that in the first case the embryo feeds mainly on the basis of substances contained in the yolk of the egg , and is separated from the metabolism in the maternal organism (nevertheless communication with the maternal organism is possible). In viviparous animals, the embryo feeds directly from the maternal organism.
Egg breeding has arisen in some species of lizards as an adaptation to life in temperate climates . Higher mammals ( placental ) are the only large taxonomic group that has developed the practice of direct live birth. All other species that give birth to their babies alive are egg-breeding. Exceptions are only the majority of kharharonidnyh sharks (including hammerhead sharks ) and onychofors .
See also
- Egg laying
- Live birth