SEXUAL REPRODUCTION in animals - Types and examples

Animals, as individual organisms, appear and disappear, but the species a which we belong is maintained, all thanks to reproduction, one of the vital functions of living beings.Within the animal kingdom we can find two reproductive strategies, asexual reproduction and sexual reproduction, more widespread among animals.

sexual reproduction is the typical reproductive strategy of animals, although some of them can be reproduced exceptionally by means of an asexual strategy.Therefore, in this article of Animals and Pets Online we will explain that is the sexual reproduction of animals .

Characteristics of sexual reproduction of animals

Sexual reproduction is the reproductive strategy that many animals and plants carry out to give rise to new individuals that perpetuate the species.

The characteristics that define this type of reproduction are several In the first place, in the sexual reproduction there are two individuals involved, unlike the asexual reproduction that is only one, a female and a male.Both of them have organs known as gonads that produce gametes.These gametes are the sex cells , ovules in females, generated by the ovaries and sperm produced by the testicles in males.

When an egg and a sperm fuse, they give rise to a zygote.This union is called fertilization.Fertilization can occur within or outside the animal, according to the species, so there is external fertilization where females and males expel their gametes to the aquatic environment to be fertilized and internal fertilization, where sperm meet tran elovulo inside the female.

After fertilization, the zygote formed will have 50% maternal DNA and 50% paternal DNA, that is, the offspring that occurs through sexual reproduction you will have genetic material of both parents.

Stages of sexual reproduction of animals

Sexual reproduction in animals consists of several stages, beginning with gametogenesis.This phenomenon consists in the formation and development of female and male gametes within female and male gonads respectively.

From germ cells and through a type of cell division known as meiosis, both females and males create their gametes.The rate of creation and maturation of gametes will depend on several factors but, mainly, on the species and sex of the individual.

After gametogenesis, the mechanism by which fertilization occurs is mating.Mediated by hormones, fertile-aged individuals will seek the company of the opposite sex to mate and, after courtship, The copula will be produced in those animals that have internal fertilization.The species with external fertilization will release the gametes to the environment so that they can be fertilized.

After fertilization the last phase of reproduction occurs sexual ion, fertilization, which consists of a series of molecular changes that allow the fusion of the nucleus of the nucleus with the nucleus of the sperm.

Types of sexual reproduction of animals

The types of sexual reproduction existing in animals are related to the size of the gametes that are to be joined in fertilization, so we find isogamy, anisogamy and oogamy.

Isogamy is the fusion of two gametes of similar size, it is not possible to visually differentiate which is the male or female gamete.Both one and the other can be mobile or immobile.It is the first type of sexual reproduction that appeared in the evolutionary history and is typical of chlamydomonas (unicellular algae) and monocystis, a protist.It does not occur in animals.
Anisogamy is the fusion of gametes of different sizes.There are differences between male and female gametes, and both can be mobile or immobile.It appears later in evolution than isogamy.It occurs in fungi, superior invertebrates and other animals.
Oogamy is the fusion of a very large and immobile female gamete with small mobile male gametes.Is The last type of reproduction that appears in evolution is typical of higher algae, ferns, gymnosperms and animals such as vertebrates.

Examples of sexual reproduction in animals

There are as many examples of sexual reproduction as there are animal species.

Mammals such as dogs, chimpanzees, whales or humans have sexual reproduction with internal fertilization and oogamy, they are also viviparous animals, so that embryonic development will take place in the womb.
Birds, although they lay eggs as oviparous animals, also follow this sexual reproductive strategy with oogamy.
Reptiles, amphibians and fish also reproduce sexually, although certain species follow an asexual strategy at certain times in their lives.Some are oviparos and other ovoviviparos, many of them have external fertilization and many others internal.
Arthropods are a large and diverse group of animals, so in this group we will find both internal and external fertilization and cases of oogamy and anisogamy.Some may reproduce asexually.

Do not forget that they exist hermaphroditic animals, with female and male reproductive organs at the same time, but can only act as female or male before mating.Self-fertilization does not occur.

If you want to read more articles similar to Sexual reproduction in animals-Types and examples , we recommend that you enter our Curiosities section of the animal world.

Bibliography

Crow, JF (1994).Advantages of sexual reproduction.Developmental genetics, 15 (3), 205-213.
Panawala, L.(2017).Difference Between Anisogamy Isogamy and Oogamy.ResearchGate.Available at: https://www.researchgate.net/publication/316921070_Difference_Between_Anisogamy_Isogamy_and_Oogamy
Sawue, H.wow, H.N.,&Iwano, M.(2014).Sexual reproduction in animals and plants.Springer-Verlag GmbH.

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