Understanding the Difference between Internal and External Fertilization
Fertilization is a vital process for the reproduction of organisms. However, there are two primary ways that fertilization can occur. These are internal and external fertilization. Both processes are vastly different and have their own unique advantages and disadvantages. Here we will explore the differences between internal and external fertilization.
Internal Fertilization
Internal fertilization is the process of sexual reproduction where the sperm is deposited inside the female’s body. This is common in most land-based animals and some aquatic animals. The male transfers the sperm into the female’s reproductive system, where it then fertilizes the egg. Internal fertilization has a few advantages:
– Increased chances of fertilization: With internal fertilization, the chances of sperm reaching the egg are higher compared to external fertilization. This is due to the fact that the sperm is directly deposited near the egg, leading to fertilization.
– Greater control over offspring: Internal fertilization provides greater control over the offspring. The female can choose the best sperm to fertilize her eggs, leading to stronger and fitter offspring.
– Protection of embryos: The embryos get protection inside the female’s reproductive system, where they can develop and mature shields from external influences.
External Fertilization
External fertilization occurs when fertilization happens outside the female’s body. This process is common in aquatic animals such as fish and amphibians. The female lays eggs in the water, and the male deposits the sperm over the eggs. External fertilization has a few advantages:
– Greater genetic diversity: With external fertilization, multiple males can fertilize multiple eggs, leading to greater genetic diversity in the offspring.
– Lesser energy expenditure: External fertilization requires no energy expenditure compared to internal fertilization, where the male needs to transfer sperm inside the female body.
– Large number of offspring: With external fertilization, thousands of eggs can be fertilized in a single mating act, leading to a larger number of offspring.
Conclusion
Internal and external fertilizations have their benefits and drawbacks. Internal fertilization offers greater control over offspring, greater chances of fertilization, and protection of embryos. On the other hand, external fertilization has greater genetic diversity, requires lesser energy expenditure, and produces larger numbers of offspring. However, each species selects a fertilization method that complements its life cycle and environmental requirements for increased chances of survival.
Table difference between internal and external fertilization
| Internal Fertilization | External Fertilization |
|---|---|
| Occurs inside the body of the female | Occurs outside the body of the female, in water or on land |
| Sperm are directly deposited into the female’s reproductive system | Eggs and sperm are released into the environment and come together outside the body of the female |
| Enables the development of complex reproductive structures and behaviors | Requires less complex reproductive structures and behaviors |
| Provides protection and nourishment for developing embryos | Embryos are not protected and must rely on external factors for survival |
| Allows for greater control over the selection of mates and genetic traits | Less control over mate selection and genetic traits |