Ans: There are two types of fertilization in animals-External Fertilization: When fertilization happens outside an animal's body, the process is called external fertilization. Aquatic animals like fish and frogs conduct external fertilization. Wherein, a large number of eggs are fertilized in this method before it gets washed away by the water.Internal Fertilization: When fertilization takes place inside the body, the process is called internal fertilization. Terrestrial animals perform this type of fertilization.