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💡 Inside or outside?
A frog scatters its eggs into a pond; a bird keeps its egg safe inside first. Where the gametes meet changes everything about how many young survive.
What are external and internal fertilisation?
- In external fertilisation , the female releases eggs into water and the male releases sperm over them (frogs, most fish); many eggs are laid but many are lost.
- In internal fertilisation , fertilisation takes place inside the female’s body (reptiles, birds, mammals).
- Survival of young ones is generally higher in internal fertilisation because the fertilised egg or embryo is better protected.
