Internal Fertilization vs. External Fertilization

The major difference between two types of fertilization is that in the internal fertilization, male and female gametes unite within the female body using a copulative organ while in the external fertilization, male gametes unite with the female gametes occurs outside the female body usually in the water.

Internal Fertilization vs
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We all know about the process of fertilization that it is the union of male and female gametes to produce the next progeny. Broadly, fertilization can be divide into two types, internal fertilization, and the external fertilization. External fertilization occurs outside the body of the female usually in water or any other external environment while internal fertilization takes place within the body of the female using the copulative organ of the male.

Internal fertilization is carried out by the birds and mammals while external fertilization takes place by a few amphibians and mostly aquatic animals.

In the internal fertilization, less number of sperms or male gametes are secreted via ejaculation which is entered in the female body while in the abundant number of gametes are secreted in the external environment mostly water.

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In the internal fertilization, only male gametes are released while in the external fertilization, both male and female gametes are released in the external environment.

The process of fusion of the gametes and further development (syngamy) occurs inside the female genital tract in case of the internal environment while fusion and further process of development takes place in the external environment in case of external fertilization.

Internal fertilization is further divided into three types according to the process of fertilization, i.e., oviparity, viviparity, and ovoviviparity. While external fertilization is not further divided into any further types.

The advantages of internal fertilization are, offspring survival chances are enhanced within the safe environment inside the body of the mother. Chances of successful fertilization are also enhanced. Offspring can survive even in a harsh environment. The advantages of external fertilization are, offspring are developed in much abundant number. Less amount of energy is consumed in mating. Competition between offspring and parents is less.

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The disadvantages of internal fertilization are, high energy is required for mating. It is also a time-consuming process to find a mate. Offspring are produced less in number. Larger contribution from the female parent is required. The disadvantages of the external fertilization are, the chances of survival of the offspring are greatly reduced because of the harsh external environment. Less care and protection of the offspring leads them to death. The offspring can survive only in the wet or moistened environment.

Contents: Difference between Internal Fertilization and External Fertilization

Comparison chart

Basis Internal fertilization External fertilization
Definition It is a type of fertilization in which the union between male and female gametes occurs inside the body of the female. It is a type of fertilization in which both the male and female gametes occurs outside the body of the female.
Takes place in Internal fertilization is carried out by birds and mammals. It is carried out by amphibians and aquatic animals.
Gametes are released in Only male gametes or sperms are secreted from the body of the male partner. Both male and female gametes are secreted from the bodies of both male and female partners.
Offspring production Offspring are produced in less number. Offspring are produced in abundant number.
The environment provided to the offspring Offspring are provided with a safe environment within the body of the mother. Offspring have to face harsh environment outside the body of the mother.
Subtypes It is further divided into three types, i.e., oviparity, viviparity, and ovoviviparity. External fertilization is not further divided into types.
Advantages The advantages are, chances of offspring survival are enhanced, offspring do not have to face a harsh environment, it is a very safe method. The advantages of this type are, offspring are produced abundant in number, less amount of energy is required for fusion of both gametes and less competition between parents and offspring.
Disadvantages The disadvantages of this type are, more amount of energy is required for mating, offspring are produced less in number, more competition between parents and offspring. It is a time-consuming process to search for a mate, and a large contribution from the female side is required. The disadvantages of this type are fewer chances of survival of the offspring because of the harsh external environment. Less care and protection of the offspring leads them to death. Offspring produced can survive only in a wet and moist environment.

What is internal fertilization?

Internal fertilization is a type of fertilization in which the male gametes or sperms unite with the female gametes inside the body of the female. Male gametes are entered in the body of a female via the male copulative organ. This type of fertilization takes place in the terrestrial animals, i.e., the animals who live on land. Although it may occur in some of the aquatic animals. This method is carried out in three ways, i.e., oviparity, viviparity, ovoviviparity. Oviparity is carried out in the animals who lay eggs outside. These animals are termed as oviparous. The nutrition of the offspring is provided by the yolk. Viviparity is carried out in mammals and in few reptiles. In this type, offspring are reproduced and developed within the body of the mother, receive nutrition via placenta and later born out. In ovoviviparity, eggs are produced and retained within the body of the mother and nutrition to the offspring is provided via yolk.

What is external fertilization?

External fertilization is the type of fertilization in which the male gametes unite with the female gamete outside the body of the female in the external environment mainly in water. This type of fertilization takes place in a few vertebrates, fishes, sea urchins, most of the amphibians and all aquatic animals. When male and female gametes are deposited in the external environment, this process is known as spawning. Offspring are produced in large number in this type, but they have to face the harsh external environment so not all the offspring survive. The benefit is that less amount of time and energy is required to find a mate in this type.

Key Differences between Internal Fertilization and External Fertilization

  1. In Internal fertilization, male gametes unite with the female gametes within the body of the female while in the external fertilization, male gametes unite with the female gametes outside the body of the female, mainly in water.
  2. In the internal fertilization, a large contribution from the female side is required while in the external type, the contribution from both male and female side is equal.
  3. In the internal fertilization, less number of offspring are produced while in the external fertilization, an abundant number of offspring are produced.
  4. In the internal fertilization, more chances of survival of the offspring while in the external type, fewer chances because of the harsh external environment.
  5. In the internal type, a large amount of time and energy is required for a mate while in external type, less time and energy is consumed.

Conclusion

Fertilization is the method to produce progeny in living organisms. It is broadly classified into two types, i.e., internal fertilization and external fertilization. One must know the differences between internal and external fertilization. In the above article, we learned the clear differences between the two types of fertilization.

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