Question

Fertilisation cannot be external in land animals. Why?

Answer 1

External fertilization is the type of fertilization in which the male and female gametes fuse outside the body of the female. Both male and female lay or release their gametes into the water where they fuse together to form a zygote. External fertilization requires a medium in which the gametes can float and come in contact so as to fuse together. For this purpose, water turns out to be the best medium. Also, water prevents the gametes from dying of desiccation. The lack of adequate amount of moisture on land and hence, the lack of survival chances makes it impossible for external fertilization to take place there.