External
internal
internal
Internal fertilisation: there usually only a few offsprings.(e.g. Human) external fertilisation : yhere are usually hundreds or thousands of offsprings.(e.g frog)
Because - external fertilisation is 'left to chance'. There's no guarantee that every egg laid will be fertilised by sperm. Internal fertilisation is much more successful.
internal because they give eggs and so they have a internal fertilisation
Marine mammals have internalized genitalia for streamlining.
external
internal
The 2 fertilisation's are external fertilisation, or internal fertilisation. External fertilisation is the type frogs do.
internal is in and external is out fertilisation
VERY INTERNAL
internal
i think internal
internal
internal
Yes
arthropods usually have external fertilization
Yes.