Fertilisation in animals takes place in one of two ways: either by internal fertilisation, inside the body of female, or by external fertilisation, outside the body of the female animal.

Internal fertilisation

Internal fertilisation occurs in all land animals, like mammals, birds, reptiles and insects. It also occurs in aquatic mammals, aquatic reptiles and in sharks.

During sexual union, or copulation, the male deposits his sperm inside the female’s body.

External fertilisation

External fertilisation occurs in water. The female deposits ova in the water, and the male deposits sperm. The sperm then swim to the ova to fertilise them.

External fertilisation occurs in nearly all aquatic animals, from fish to sponges.

Types of Fertilisation