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How does internal fertilisation differ from external fertilisation?

Internal fertilisation occurs inside the body, while external fertilisation happens outside the body in the environment.

Internal fertilisation is a reproductive strategy where the sperm fertilises the egg inside the body of the female. This is common in many terrestrial animals, including mammals, birds, reptiles, and some insects. The male deposits sperm directly into the female's reproductive tract, often through copulation. This method of fertilisation has several advantages. Firstly, it protects the gametes from desiccation and other environmental hazards. Secondly, it allows for greater parental care and protection of the offspring during their early development. However, the number of offspring produced is usually lower compared to external fertilisation.

External fertilisation, on the other hand, occurs outside the body, typically in a moist or aquatic environment. This is common in many aquatic animals, such as fish and amphibians. The female releases her eggs into the environment, and the male then releases his sperm over the eggs. This method of fertilisation can result in a large number of offspring, increasing the chances of survival for some. However, the eggs and sperm are exposed to the environment, making them vulnerable to predation, disease, and changes in environmental conditions. Additionally, the chances of fertilisation can be lower due to the dispersion of gametes in the environment.

In summary, the main difference between internal and external fertilisation is where the process takes place - inside or outside the body. Each method has its own advantages and disadvantages, and the choice between the two often depends on the specific environmental conditions and life history traits of the species.

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