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The animals oviparous are those that reproduce through eggs. In this way, the embryo develops inside the egg, but outside the maternal body, until, once, its development has finished, the egg hatches and the new individual is born. In animals viviparousOn the contrary, the embryo develops completely within its mother's womb and there is a third group, the ovoviviparous, which keep the eggs inside during the development stage and once the embryo has matured and is ready to hatch, the eggs hatch and the mother releases the young.
However, although all oviparous animals lay and hatch from an egg, the procedure of fertilization, care and protection of the egg and the rearing varies enormously depending on the species in question. In Green Ecologist we explain what are oviparous animals and their different behaviors and techniques.
Fertilization in oviparous animals
Fertilization is the stage in which the genetic material of the female and the male, the ovary and the sperm, respectively, come into contact to give rise to the new individual. In oviparous animals, fertilization can be of two types:
- Internal fertilization: It is typical of all those animals that lay "dry" eggs, such as birds and reptiles. In this way, the eggs are fertilized by mating prior to laying.
- External fertilization: It is typical of animals that lay “soft” eggs, laid in a watery or humid environment, as in the case of fish or amphibians. The female does the laying of the egg without fertilizing and it is, after laying or during it, when the male pours his sperm on the eggs to fertilize them.
All birds are oviparous, as are most insects, fish, amphibians, reptiles, and even some mammals.
Oviparous animals that are birds
While some birds make their nests exclusively for laying and caring for their eggs, others simply lay them between rocks, bushes or on the ground, as is the case with chickens.
After you have put the egg, the female incubates it and provides heat for about two weeks, depending on the incubation time of the species in question, until they hatch and the chicks hatch. The female, and in some bird species The male, too, will continue to protect, care for and provide food to his chicks until they reach a suitable maturity stage, as in the case of ducks or the ability to fly, depending on their species, being an example of species that abandon the nest, from storks, eagles, sparrows, etc.
Reptiles, oviparous animals
Reptile eggsGenerally, they are designed to be able to protect the young against arid or hostile conditions, so that their shell is more resistant and in turn, it has tango reserves of water as well as nutrients. As reptiles are cold-blooded, they cannot incubate or provide heat to their eggs through their bodies, so they use sunlight or other natural heat sources to hatch them, although there are some species, such as the python, that they do have an adequate body temperature.
As for the care of the egg or the young, there are species that after laying do not even incubate the egg and leave it to its fate, such as turtles that lay their eggs on the beaches and bury them, while others, such as snakes and crocodiles, take care of the care of their young until they reach an adult stage.
Fish and amphibians, animals that lay eggs
Fish and amphibians can perform the laying their eggs in very varied places: between stones and plants, in holes carved in the bottoms of oceans and rivers, in nests made from foam, in water or even on other individuals. In addition, the appearance of the egg varies a lot depending on the species, being able to present red, yellow, transparent colors and very varied sizes and its fertilization is mainly external, although there are exceptions. In fact, not all fish are oviparous, but some are viviparous or ovoviviparous, presenting internal fertilization.
Unlike birds, reptiles and mammals, both fish and amphibians that hatch from the egg are not fully formed, but must go through a larval period in which they develop until they reach the characteristics of the species. A well-known example of this type of development is that of some amphibians such as frogs.
Regarding the care of the young once it has been born, it should be noted that, there are species that abandon their eggs to their fate, such as carpines and barbels and others that take care of both the egg and the fry after their birth, such as this is the case of some catfish or harlequins. There are also species that, after laying the egg, die, as for example in the case of piranhas.
Oviparous or egg-laying mammals
There are only two species of oviparous mammals:
- Platypus: fertilization occurs internally, so that, after mating, the females build a nest / burrow in the form of a tunnel in which they deposit their eggs, usually between one and three eggs. It should be noted that before the egg is laid, it remains in the womb for about 28 days and after laying they are incubated for at least 10 days. During that period of time, the female is responsible for incubating and protecting them until they hatch. After birth, the female will continue to feed and care for her young in the burrow until she reaches the developmental stage necessary to get her own food.
- Echidnas: In this species of mammalian animals, fertilization takes place internally. After mating, the female gestates a single egg for about 22 days in her womb and then she lays and continues to incubate it in a kind of bag for 45-50 days.
Find out more about this in this other Green Ecologist article on the List of names of animals that lay eggs.
If you want to read more articles similar to What are oviparous animals, we recommend that you enter our category of Animal Curiosities.
