Question

Why do animals with external fertilisation generally produce more eggs than animals with internal fertilisation?

Answer 1

In external fertilisation, eggs and sperm are released into water where many eggs are destroyed by water currents, predators, or unfavourable conditions. Producing a large number of eggs increases the chance that at least some will be fertilised and survive. In internal fertilisation, the gametes and embryo are protected inside the female body, so fewer eggs are needed.