Understanding External and Internal Fertilisation – Key Differences
Fertilisation is the fusion of male and female gametes (sperm and egg) to form a zygote, leading to the development of a new organism. Based on where fertilisation occurs, it is classified into External Fertilisation and Internal Fertilisation.
Understanding the difference between external and internal fertilisation helps in learning how different species reproduce and adapt to their environment. Let’s explore each type in detail.
What is External Fertilisation?
External fertilisation is a process in which fertilisation occurs outside the female’s body, typically in an aquatic environment. This method is common in fish, amphibians, and some invertebrates.
What is Internal Fertilisation?
Internal fertilisation is a process in which fertilisation occurs inside the female’s body. It is common in mammals, birds, reptiles, and some fish. This method protects the developing embryo.
Key Differences – External Vs Internal fertilisation
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FAQs on Difference Between External and Internal Fertilisation
1. What is the main difference between external and internal fertilisation?
In external fertilisation, sperm and eggs meet outside the female’s body, while in internal fertilisation, fertilisation occurs inside the female’s reproductive system.
2. Why do aquatic animals mostly use external fertilisation?
Water provides a medium for sperm to swim and reach the egg, increasing the chances of fertilisation.
3. Which organisms use internal fertilisation?
Mammals, birds, reptiles, and some fish rely on internal fertilisation for reproduction.
4. Is external fertilisation more efficient than internal fertilisation?
External fertilisation produces more gametes but has a lower survival rate, while internal fertilisation produces fewer gametes but offers better protection.
5. Why do mammals use internal fertilisation?
Mammals give birth to fewer offspring, and internal fertilisation ensures greater protection for developing embryos.
6. Do all fish use external fertilisation?
No, while most fish use external fertilisation, some species like sharks use internal fertilisation.
7. How does parental care differ in external and internal fertilisation?
External fertilisation: Little to no parental care (e.g., fish, amphibians).
Internal fertilisation: High parental care (e.g., mammals, birds).
8. Which fertilisation type has a higher success rate?
Internal fertilisation has a higher success rate since it protects against environmental hazards.
9. Can an organism use both external and internal fertilisation?
No, species are adapted to one method based on their environment and reproductive strategy.
10. Why do amphibians like frogs use external fertilisation?
Frogs lay eggs in water, where sperm fertilizes them externally, ensuring a higher number of offspring.
