In animals, gametes are called sperm (male) and eggs (female). Fertilisation may take place in water, for example, male and female fish or frogs eject sperm and eggs, respectively, into the water where they combine to form the zygote. In birds and mammals, including humans, sperm are deposited inside the female, and fertilisation takes place when the sperm swim towards the egg produced by the female.
Q.1. What is the difference between fertilisation in fish and birds?
Q.2. Why do fish produce many eggs compared to birds?
Q.3. How does internal fertilisation benefit mammals like humans?