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Sexual Reproduction in Animals – Detailed Explanation

Sep 9, 2022
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Key Concepts

  • Sexual Reproduction
  • Gametes
  • Fertilization
  • Oviparous
  • Viviparous
  • Internal and External Fertilization

Introduction

Sexual reproduction is a natural mode of reproduction for humans, animals, and the majority of plants. In comparison to asexual reproduction, sexual reproduction is more complex and time-consuming.  

Furthermore, sexual reproduction provides variation, and children are distinct. A series of events occur during sexual reproduction. Pre-fertilization, fertilization, and post-fertilization are the three stages of the process. 

Sexual reproduction is a type of reproduction that involves two parents giving birth to their young ones. 

Males and females have reproductive organs that are distinct. 

Male and female gametes are produced in the reproductive organs, and they combine to make the progeny. 

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Both parents’ genetic information is inherited. 

Genetic differences in the progeny result from the fusing of these gametes. By generating genetic variation, sexual reproduction fosters character diversity in offspring. Sexual reproduction is, therefore, extremely efficient. 

Sexual reproduction

Explanation

Sexual reproduction explained in three stages:  

Pre-fertilization

Pre-fertilization is the first step in the fertilization process. 

The events preceding fertilization are included in this stage. 

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 The two processes that take place during this stage are gamete formation (gametogenesis) and gamete transfer. Males and females have different gametes, which are haploid cells with 23 chromosomes.  

Sperm refers to male gametes, while ovum or egg refers to female gametes. These gametes develop in specific structures in every creature.  

Male gametes must be transported in order to fertilize female gametes, which are immobile. Pollination is how plants pre-fertilize.  

Sexual intercourse is how unisexual animals transfer their gametes. 

Gamete formation and gamete segregation

Fertilization

Fertilization is the second step in the process of reproduction. 

Fertilization, is the meeting and fusion of haploid male and female gametes to generate a zygote. External fertilization takes place outside of the body, while internal fertilization takes place inside the body. 

Fusion of gametes

Post-fertilization

Fertilization results in the creation of a diploid zygote.  

The zygote eventually divides and develops into an embryo by mitotic division. Embryogenesis is the name for this process. 

Cells differentiate and alter themselves during development. The organism and its life cycle influence zygote formation. 

 Formation of zygote

Depending on whether the zygote grows outside or inside the body, animals are classified as oviparous or viviparous. 

Oviparous animals

Oviparous animals are terrestrial organisms that lay eggs. Fertilization can take place either internally or externally, but embryonic development takes place outside of the female’s body in the egg. 

Examples of oviparous animals

Viviparous animals

The word viviparous comes from the Latin words ‘vivius’, which means alive, and ‘parere,’ which means to bring forth. 

It describes animals that give birth directly to live offspring rather than eggs.  

Both oviparous and viviparous animals undergo internal fertilization.  

Embryo development in viviparous animals occurs within the female member of that species. 

Examples of viviparous animals

The differences between oviparous and viviparous animals. 

 Comparison between oviparous and viviparous animals

External fertilization and internal fertilization are the two kinds of fertilization in animals. 

External fertilization

External fertilization occurs when fertilization occurs outside of the animal’s body. Most aquatic creatures, such as fish and frogs use external fertilization. 

Because most fertilized eggs are washed away by water or eaten by predators, this approach requires a high number of eggs to be fertilized. A large number of eggs ensures that some of the progeny will survive. 

External fertilization

Internal fertilization

Internal fertilization occurs when fertilization occurs within the animal’s body.  

The majority of terrestrial animals undergo internal fertilization. Internal fertilization, unlike external fertilization, does not necessitate the production of a significant number of eggs. 

 Internal fertilization

Sexually reproducing animals begin with a zygote, which develops into an embryo and then matures into an adult. Sex cells are produced by adults (egg and sperm). 

 The zygote is formed when sperm and egg combine. Life-cycle refers to the entire cyclic order. 

The general sexual reproductive cycle

Summary

  • Reproduction: The process of reproduction allows an organism to generate its young one.
  • Sexual reproduction: A process in which two parents take part in producing the young
    one.
  • Asexual reproduction: When a single parent divides and reproduces its offspring by itself.
  • Sexual reproduction is a natural mode of reproduction for humans, animals, and the
    majority of plants. In comparison to asexual reproduction, sexual reproduction is more
    complex and time-consuming.
  • Pre fertilization: The two processes that take place during this stage are gamete
    formation (gametogenesis) and gamete transfer.
  • Fertilization, or syngamy, is the meeting and fusion of haploid male and female gametes
    to generate a zygote.
  • Post fertilization: Fertilization results in the creation ofa diploid zygote.
  • Oviparous animals are terrestrial organisms that lay eggs. Fertilization can take place
    either internally or externally, but embryonic development takes place outside of the
    female’s body in the egg.
  • Viviparous animals describe animals that give birth directly to live offspring rather than
    eggs.
  • External fertilization: External fertilization occurs when fertilization occurs outside of the
    animal’s body. Most aquatic creatures, such as fish and frogs use external fertilization.
  • Internal fertilization: Internal fertilization occurs when fertilization occurs within the
    animal’s body.

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