The reproduction of animals is a complex process that occurs in various ways, in this sense, this group of living beings has developed, thanks to evolution, different reproductive patterns to guarantee the maintenance of each species, in such a way that we find several interesting ways in which animals manage to perpetuate themselves, since they have strategically adapted to optimize this vital process.
Before all the existing distinctions, it has been possible to establish a classification of animals according to their reproduction,and in this article on our site, you will be able to document yourself on this important topic.
Reproduction in animals
In the animal world, the reproduction of animals can take two forms:
- Asexual reproduction: In asexual reproduction, identical offspring originate from a single parent, which can occur in different ways. Hermaphrodite species fall into this group.
- Sexual reproduction: The other form of reproduction is sexual, which occurs through the union of the genetic material of two individuals. In sexual reproduction, fertilization can occur externally or internally. In the first case we have as an example fish, amphibians and many invertebrates. The second case is typical of most reptiles, birds and mammals. For its part, the development of the zygote can also occur inside or outside the female, although the nutrition of the embryo can be dependent or independent of the mother.
A special case is that of hermaphrodite animals, which can have different reproductive strategies. For further information, we advise you to read this other article on our site on Reproduction in animals.
How are animals classified according to their type of reproduction?
The classification of animals according to the type of reproduction is established depending on where the development of the embryooccurs, that is, if gives inside or outside the body of the female. In this way, we have this type of animals:
- Oviparous animals.
- Ovoviviparous animals.
- Viviparous animals.
Now, even though the previous categorization exists, we also find several exceptions, because in the same group of animals we can find different patterns reproductive. Such is the case of mammals, the vast majority of which are viviparous. However, the order Monotremata includes species that are classified as oviparous due to their reproductive characteristics.
Oviparous animals
In oviparous animals, fertilization can occur inside or outside the body, but the development of the embryo will always take place outside the body of the femaleThus, the characteristics of the egg are essential for it to develop outside the mother, which is why some oviparous produce dry eggs that are capable of withstanding the contact with the air, since they have a protective cover (shell), as is the case with birds and reptiles. The largest egg in this type of reproduction that we find today is that of the ostrich (Struthio camelus). Other groups of oviparous, such as most fish, some reptiles, amphibians and insects produce smaller eggs, they are not calcified and, in many cases, the process occurs in the aquatic environment.
Within the oviparous, we also find the presence of two primitive mammals that reproduce in this way: the platypus (Ornithorhynchus anatinus) and the echidna, such as the species Tachyglossus aculeatus, which are animals covered with spines.
Some oviparous animals leave their eggs once they are expelled, leaving them exposed at random, while others take care of them and provide the necessary protective conditions, even storing food to nourish the young once they hatch.
Examples of oviparous animals
Some examples of oviparous animals are:
- Birds: ostriches, chickens, ducks, geese, penguins, parrots, hummingbirds, storks.
- Fish: anchovies, piranhas, eels, salmon, tuna.
- Reptiles: snakes, lizards like the Komodo dragon, turtles, crocodiles.
- Insects: ants, bees, beetles, flies.
- Molluscs and crustaceans: snails, octopus, crabs.
- Mammals: platypus and echidna.
Ovoviviparous animals
When animals born from eggs, but fertilization is internal and embryonic growth also occurs inside the mother, not intervening directly in nutrition and development, then the classification of the animal is ovoviviparous. The hatching of the egg can occur within the mother's body, so that during delivery it can The hatchling will come out directly or the egg will be expelled to the outside, opening immediately or shortly after. As in the case of oviparous animals, the nutrition of the offspring depends on the egg, so this is essential in this regard. This group is made up of various types of invertebrates, some fish, such as the great white shark (Carcharodon carcharias) and certain reptiles, such as the Trioceros jacksonii species, which is a type of chameleon.
Examples of ovoviviparous animals
Some examples of ovoviviparous animals are:
- Reptiles: Rattlesnake, some lizards.
- Amphibians: some species of salamanders.
- Fishes: great white shark, manta ray.
- Insects: certain species of flies.
Viviparous Animals
Viviparous animals are those whose fertilization is internal and the embryo develops inside the mother's body. However, in this case, it is the mother who provides nutrition and protection throughout the process because there is total dependence between the two until the moment of birth. Here we find almost all mammals, including bats. Marsupials are also viviparous, however, their reproductive system differs from the rest, since the embryo is born without being fully developed and the process ends in the marsupial bag, as for example in the species Phascolarctos cinereus, commonly known as koala.
As in the previous classifications of animals according to their reproduction, there are certain exceptions, for which it is also possible to findspecies of arthropods , such as scorpions, that reproduce in this way. An example is found in Androctonus crassicauda, known as the fat-tailed scorpion. Another example of these singularities is found in the subspecies Salamandra salamandra bernandezi , a case of a viviparous amphibian.
Examples of viviparous animals
Some examples of viviparous animals are:
- Mammals: All except the platypus and echidna.
- Fish: Some sharks, such as hammerheads.
- Reptiles: Some snakes, such as boas and certain lizards.
- Amphibians: some species of salamanders.
The classification of animals according to their reproduction corresponds to a complex process, since as we have seen in this article, there are always exceptions within the animal kingdom, therefore, absolute categorizations cannot be established to define each group as oviparous, ovoviviparous, or viviparous. In this way, the peculiarities of the species must always be taken into account in order to establish an adequate classification according to their reproductive mode.
Now that you know the classification of animals according to their reproduction, you may be interested in reading this other article on the Classification of animals according to their diet.
