Difference between Internal Fertilization and External Fertilization
What is Fertilization?
Fertilization, in biology, is the process where sperm and a female egg meet to form a new organism. The two main types of fertilization are external fertilization and internal fertilization.
External Fertilization
External fertilization is a process where the fertilization of the egg occurs outside the body of the female. It is a common process in aquatic animals like fish, amphibians, and many aquatic invertebrates. During external fertilization, the male and female release their reproductive cells in the water, where the sperm swim towards the female’s egg. The sperm fertilizes the egg, and the zygote is formed, which further develops into an embryo.
Internal Fertilization
Internal fertilization is a process where the sperm fertilizes the egg inside the female’s body. It is a common process for terrestrial animals like reptiles, mammals, and birds. To achieve internal fertilization, the male needs to insert his sperm through the female’s reproductive organs, and the sperm fertilizes the egg. After fertilization, the embryo remains in the female’s body, where it grows and develops to full term.
Difference between Internal and External Fertilization
The primary difference between internal and external fertilization is the location of which the fertilization occurs. In external fertilization, the fertilization occurs outside the female’s body, whereas, in internal fertilization, the process of fertilization takes place inside the female’s body.
Another significant difference is the number of offspring produced. Typically, external fertilization produces more offspring since a large number of eggs and sperm are released. However, the chances of the fertilization of eggs are lower in external fertilization than in internal fertilization.
In conclusion, depending upon the animal kind, internal and external fertilization has been evolved as per the environmental adaptations. Though the process of fertilization may differ in their mechanism, the ultimate goal is the same, that is to produce offspring.
Table difference between internal fertilization and external fertilization
| Internal Fertilization | External Fertilization |
|---|---|
| Occurs inside the body of the female organism. | Occurs outside the body of the female organism. |
| Sperm fertilizes the egg inside the female’s reproductive system. | Eggs and sperm are released into the environment simultaneously. |
| The survival rate of offspring is usually higher due to the protection provided by the female’s body. | The survival rate of offspring is lower as they are exposed to predation and other environmental factors. |
| Internal fertilization usually results in fewer offspring due to the limited space and resources inside the female’s body. | External fertilization usually results in a larger number of offspring as the eggs are released in large quantities. |
| Examples of animals that undergo internal fertilization include birds, mammals, reptiles, and some fish. | Examples of animals that undergo external fertilization include most fish, amphibians, and some invertebrates such as sea urchins and corals. |