Reproduction is the property of living organisms to reproduce similar individuals. Animals reproduce asexually and sexually. Asexual reproduction is characteristic mainly of lower animals. During asexual reproduction, a part of her body is separated from the mother or the whole individual is divided into two or more parts, each of which develops into an independent animal. There are several ways of asexual reproduction of animals: division, budding, schizogony (Fig. 23).

Budding is such asexual reproduction, when an outgrowth (bud) is formed on the body of the mother individual, gradually acquiring the shape and structure of an adult animal. After separation (budding) from the mother's organism, a new individual begins to lead an independent life.

In some multicellular animals (usually living in water), external fertilization is observed: both eggs and spermatozoa are released into the water, where they merge. Other animals tend to be internally fertilized: the sperm is introduced into the genital tract of the female, and there the act of fertilization of the egg by the sperm takes place.