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Difference Between Internal and External Fertilization

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Distinguish Between Internal and External Fertilisation - Understanding The Process

Fertilization is the process where male and female gametes (sperm and egg) fuse to form a zygote, marking the beginning of a new organism. This biological process is essential for the reproduction of species. Fertilization can occur in two distinct ways: internal fertilization and external fertilization. Internal fertilisation refers to the union of gametes inside the female’s body.  External fertilization takes place outside the female’s body, typically in aquatic environments. In this article, we’ll explore these two types, their characteristics, and the key differences between Internal and External Fertilization.


Key Differences Between Internal and External Fertilization

Feature

Internal Fertilization

External Fertilization

Location of Fertilization

Occurs inside the female's body

Occurs outside the female’s body, typically in water

Gametes Released

Fewer gametes released and retained in the female body

Large quantities of gametes released into the environment

Development of Zygote

Inside the female body

Outside the body, in water or the external environment

Examples of Organisms

Reptiles, birds, mammals, tracheophytes, pteridophytes

Fish, amphibians, algae, aquatic invertebrates

Types

Viviparity, Oviparity, Ovoviviparity

No specific types

Advantages

Higher survival rate, parental care

Many offspring produced, less energy spent in finding a mate

Disadvantages

Requires more energy for mate finding, fewer offspring

High risk of predation, many eggs go unfertilized


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FAQs on Difference Between Internal and External Fertilization

1. What are the 3 differences between internal and external fertilization? 

Internal fertilisation occurs inside the female body, while external fertilization takes place outside, typically in water. This distinction leads to differences in gamete quantity, protection, and environmental requirements.

2. What are 5 examples of external fertilization? 

External fertilisation is observed in species like fish, frogs, sea urchins, starfish, and corals, where gametes are released into the water for fertilization.

3. What are the 3 differences between internal and external development? 

Internal development refers to the growth of the embryo within the female's body, providing protection and direct nourishment. External development occurs outside, often in eggs laid in the environment, leading to differences in survival rates and developmental stages.

4. How do internal and external fertilisation differ in terms of gamete quantity? 

External fertilization typically involves the release of a large number of gametes to increase the chances of successful fertilization, compensating for the lack of a controlled environment. In contrast, internal fertilization usually involves fewer gametes, as the process occurs within the protective confines of the female's body.

5. What are some examples of internal fertilization? 

Internal fertilization is common in reptiles, birds, mammals, and certain plants like bryophytes and tracheophytes, where sperm fertilizes the egg within the female's body.

6. How does the environment influence the choice between internal and external fertilization? 

Aquatic environments often favor external fertilization due to the medium's ability to disperse gametes, while terrestrial environments typically require internal fertilization to protect gametes from desiccation and predators.

7. What are the advantages of internal fertilization over external fertilization? 

Internal fertilization offers advantages such as increased protection for the developing embryo, higher chances of successful fertilization, and reduced risk from environmental hazards and predators.

8. How does the number of offspring produced differ between internal and external fertilization? 

External fertilization often results in a larger number of offspring due to the release of numerous gametes, whereas internal fertilization typically produces fewer offspring but with higher survival rates due to better protection and nourishment.

9. What role do environmental factors play in external fertilization?

Environmental factors such as water temperature, salinity, and timing (e.g., spawning seasons) significantly influence the success of external fertilization by affecting gamete viability and the likelihood of successful fertilization.

10. Can external fertilization occur in terrestrial environments? 

While external fertilization is primarily associated with aquatic environments due to the need for a medium to disperse gametes, some terrestrial species have evolved mechanisms to facilitate external fertilization, though these are less common.

11. How do you differentiate the environments in which internal and external fertilization occur? 

Internal fertilization takes place within the body, often in terrestrial environments, whereas external fertilization typically occurs in aquatic environments where gametes can float and meet in the water.