Difference between internal fertilization and external fertilization

Main difference

The key difference between internal fertilization and external fertilization is that in internal fertilization, a fusion of male and female gametes or fertilization occurs within the body, while in external fertilization the fusion of gametes or fertilization takes place outside the body of the organism.

Internal fertilization versus external fertilization

Fertilization is the most important step in sexual reproduction. Fertilization is the process in which the male gametes. that is, the sperm unite with the female gamete, that is, the ovum to form a new individual. There are two types of fertilization, that is, internal fertilization and external fertilization. Internal fertilization is the type of fertilization in which the fusion of gametes takes place within the body of the organism, while external fertilization is the type of fertilization in which the fusion of gametes takes place outside the body of the organism. For the most part, terrestrial organisms show internal fertilization while aquatic organisms show external fertilization. For example, reptiles and birds, etc. show internal fertilization,

Comparative chart

Internal fertilization External fertilization
The process in which the fusion of male and female gametes occurs within the body of the organism is called internal fertilization. The process in which the fusion of male and female gametes takes place outside the body of the organism is called external fertilization.
Number of gametes
Fewer gametes are released during internal fertilization and are deposited within the female’s body. Large amounts of gametes are released during external fertilization into the environment.
Gamete type
During internal fertilization, only sperm are released and deposited in the female reproductive system. During external fertilization, both the sperm and the egg are released and deposited in the external environment.
Development
In this process, the further development of the young takes place within the body of the organism. In this process, the further development of the young takes place outside the body of the organism in the external environment.
Types
There are three types of internal fertilization, that is, oviparity, viviparity, and ovoviviparity. There is no type of external fertilization.
Parental care
Due to internal fertilization, the young receive more parental care. There is less parental care during external fertilization.
Chances of survival
There is a better chance of survival due to parental care. There is less chance of survival due to less parental care.
Energy
Internal fertilization takes more energy to find a mate. External fertilization requires less energy.
Survival in harsh conditions
In internal fertilization, there are greater chances of survival of the offspring in adverse conditions. In external fertilization, the chances of survival of the offspring are reduced under difficult conditions.
Number of organisms
A small amount of offspring produced during internal fertilization. Large number of offspring produced during external fertilization.
Type of environment
Internal fertilization can occur in any type of environment. External fertilization requires a humid or aquatic environment.
Examples
Mammals, reptiles, birds, bryophytes, and tracheophytes show internal fertilization. Amphibians, Algae and Fish, etc. show external fertilization.
What is internal fertilization?

Internal fertilization takes place when the male organism directly deposits its sperm into the female body during copulation and syngamy (fusion of male and female gametes) takes place within the female body. As the individual is present within the mother’s body, the woman shows more parental care. Furthermore, it also protects the individual from harsh external conditions and increases the chances of survival of the youngster. Internal fertilization is divided into three types, that is, oviparity, viviparity, and ovoviviparity.

  • Oviparity: a type of internal fertilization in which the organism deposits the egg outside and the offspring feed on the presence of the yolk in the egg. These animals are called oviparous and their examples are birds, most amphibians, reptiles, bony fish and some cartilaginous. fish, etc.
  • Viviparity: Viviparity is a type of internal fertilization in which the offspring develop within the female’s body and are nourished by the mother with the help of the placenta. Later, a developed offspring leave the mother’s body. These animals are called viviparous. For example human, etc.
  • Ovoviviparity: type of fertilization in which the offspring develop into an egg within the mother’s body and feed on the yolk present within the egg The egg hatched when the young is fully developed. These animals are called ovoviviparous. For example sharks, lizards and snakes, etc.

What is external fertilization?

External fertilization is the type of fertilization that takes place when the male and female gametes combine outside the body. Most of the aquatic organisms present this type of fertilization. Both male and female organisms lay their eggs in the aquatic environment where syngamy occurs and new offspring are produced. Organisms with external fertilization show little parental care. In addition, the harsh external environment also reduced the chances of survival for young people. When male and female gametes deposit eggs and sperm in the open environment, it is called spawning. For example, amphibians, algae and fish, etc. show external fertilization.

Key differences

  1. The process or type of fertilization in which the fusion of male and female gametes takes place within the body of the organism is called internal fertilization, while external fertilization is the type of fertilization that takes place when the male and female gametes combine outside of the body.
  2. Fewer gametes are released during internal fertilization and are deposited within the female’s body, while a large number of gametes are released during external fertilization into the environment.
  3. In internal fertilization, the further development of the young takes place within the body of the organism, but in external fertilization, the further development of the young takes place outside the body of the organism in the external environment.
  4. There are three types of internal fertilization, p. Eg, oviparity, viviparity and ovoviviparity while there is no type of external fertilization.
  5. During internal fertilization, the young receive more parental care and protection from the hostile environment, while there is less parental care and harsher conditions during external fertilization.
  6. There is more chance of survival due to parental care in internal fertilization, while there is less chance of survival due to less parental care in external fertilization.
  7. A small number of offspring were produced during internal fertilization, while a large number of offspring were produced during external fertilization.
  8. Internal fertilization can occur in any type of environment, while external fertilization requires a humid or aquatic environment.
  9. Mammals, Reptiles, Birds, Bryophytes and Tracheophytes present internal fertilization while amphibians, algae and fish, etc. they are the example of external fertilization.

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