What is external fertilisation?

External fertilisation refers to the process where fertilisation occurs outside of an organism's body. This typically happens in aquatic environments, where the female releases eggs and the male simultaneously releases sperm into the water. The sperm then swims to the eggs to fertilise them.

This method is primarily observed in many fish and amphibian species. The benefit of external fertilisation is that it allows for a large number of eggs and sperm to be released into the environment, increasing the chances of successful fertilisation and enhancing reproductive success in species that use this method.

Options indicating fertilisation inside the female body, fertilisation without sex cells, or restricting the process to water only are not accurate descriptions of external fertilisation as they do not reflect the key characteristic of this reproductive strategy.