Difference Between Internal And External Fertilization

The process of reproduction is a complicated one. Fertilization is a primary way through which organisms reproduce. There are two types of fertilization that include internal and external fertilization. In this article, we will discuss the difference between internal and external fertilization.

What Is Internal Fertilization?

Internal fertilization is a process where the male inserts his penis into the female’s vagina and ejaculates. The sperm swims through the vaginal canal to reach an egg in one of the two fallopian tubes located on either side of a woman’s uterus.

 It is the union of male and female gametes in a sexual act. There are three types of internal fertilization that include:

  • Oviparity: In this, the fertilized egg is laid outside the mother’s body. The egg obtains nourishment from the yolk. Some of the organisms that reproduce through this process include reptiles, amphibians, and fishes.
  • Viviparity: In this form of fertilization, the young ones develop within the mother and obtain nourishment through the placenta. Humans, cats, dogs fertilize through this process.
  • Ovoviviparity: In this, the fertilized egg remains within the female, and the yolk provides nourishment to the embryo. This form of fertilization occurs in sharks, bony fish, snakes, lizards, etc.

What Are The Merits of Internal Fertilization?

Internal fertilization has many benefits, including the fact that it can lead to stronger offspring. This is because there are fewer genetic mutations as a result of being in an environment with only one copy of each chromosome rather than two. This will also make for more diverse progeny, which is much better when working on breeding animals or plants long-term.

Internal fertilization is also more efficient in terms of energy and resources. The success rate for the egg to be fully developed at birth will be higher, and a lower chance that there are any problems with it. The female animal’s body can focus on other physical needs while her eggs mature inside her instead of expending all of its resources on the process.

There is much less risk for an infection to occur when internally fertilizing because the genetic material of two individuals will be combined only after it has been screened and processed by their own bodies.

What Is External Fertilization?

External fertilization occurs outside the organism’s body. This form of fertilization generally occurs in a water body. In this, both the sperms and eggs are released into the water, mostly during spawning. Temperature and sunlight are two prominent, influential factors of this type of reproduction.

Humans also reproduce through external fertilization. In certain situations, male sperm is unable to unite with the female’s egg in a natural process. This is when humans seek for external fertilization process known as In Vitro Fertilization or IVF. The process collects freshly released sperms and eggs and combines them to start fertilization. After that, the zygote is transferred to the female’s uterus.

What Are The Merits Of External Fertilization?

External fertilization requires males to release a large number of sperms and females to release a large amount of eggs. This allows the reproduction of a large number of offspring. Moreover, considering that gametes are released into the water, they can easily move or drift, making it easier to find suitable mates. Additionally, in terms of external fertilization, there are higher chances of genetic variations.

What Are The Basis of Differences in External And Internal Fertilization?

There are two main differences between external and internal fertilization. The first is that the gametes for each process come from different sources, and secondarily, they take place in different environments resulting in a few important distinctions.

The environment of an organism can have an effect on how long it takes to produce eggs or sperm, as well as the lifespan of the gametes. In some cases where external fertilization occurs, it can help slow down an organism’s aging process by transferring a lot of nutrients and energy into reproduction-related pathways.

Moreover, in external fertilization any sperm and egg can mate. On the other hand, internal fertilization provides the opportunity of selective mating.

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 Frequently Asked Questions (FAQs)

When does internal fertilization take place?

Internal fertilization occurs at the time of sexual intercourse. It happens when a female’s egg joins with male’s sperm.

What is a good example of external fertilization?

A male frog releases sperm into the water while a female frog will release eggs, and they are taken in by the frogs that released sperm only after being dropped off there by their mother for six more weeks.