Animals, like all living things, are capable of reproducing. This means that they can give rise to new individuals of their species, allowing them to continue to exist.
Animal reproduction can be:
ASEXUAL
In asexual reproduction, a cell (or more) breaks off from the animal's body and develops, forming a new living being.
Types of asexual reproduction:
- Fragmentation or regeneration: a new individual is formed by fragmentation from a piece that accidentally came off the body of an adult. It occurs in sponges; in some flatworms, such as planarians; and in some echinoderms, such as the starfish.
Planarian regeneration.
- Budding: form, in the body of adult individuals, shoots that then detach and give rise to new individuals. Occurs in sponges.
budding in sponges.
- Gemulation: occurs to formation of structures called gemmules, when the environment is greatly altered. Thus, when the environment returns to normal, they develop and form new living beings. Occurs in sponges and coelenterates.
SEXUAL:
In sexual reproduction there is the union of two cells, one male and one female, called gametes.
It occurs in all groups of animals., even among those who reproduce asexually, such as sponges, coelenterata and echinoderms.
Types of sexual reproduction
Sexual reproduction can happen between individuals of different sexes, that is: males and females, which is the case with most animals we know. It can also occur between individuals who have both sexes, called hermaphrodites. The earthworm is an example of a hermaphrodite animal.
THE fertilization, that is, the encounter between the gametes, it can occur in the environment (external fertilization), or from bodily contact between the two individuals, usually inside the female's body (internal fertilization).
Furthermore, in sexual reproduction, new animals can become develop and be born from eggs (oviparous animals), or inside the body of a parent, usually the female (viviparous animals).
Turtle hatching from the egg: oviparous animal.
Pregnant woman: an example of viviparity.
Once born, if the puppies are very similar to the adults of their species, only small in size, we say that they have direct development.
We say that an animal species has indirect development when puppies look nothing like the adults of their species, and undergo major bodily changes until they become adults. This is the case for some amphibians, and also for butterflies and moths that, from caterpillars, go through some stages until they become animals with wings.
Indirect development: tadpole – imago – adult amphibian.
Curiosity:
From what has been explained, we can conclude that the reproduction of human beings is sexual, with internal fertilization, the children develop and are born from within the mother's body (viviparity), and the development is direct.
By Mariana Araguaia
Biologist, specialist in Environmental Education
Kids School Team
