External fertilization is the process where male organism’s sperm fertilizes female organism’s egg outside the female’s body. External fertilization occurs in water or in a moist area because it gives the sperm external mobility to get to the egg. The release of eggs and sperm into the water is known as spawning. After the sperm reaches the egg fertilization takes place. The presence of the fertilized eggs and developing young in the water provides opportunities for predators which results in loss of offspring. Therefore, a large number of eggs must be produced by individuals and the offspring produced through this method must mature rapidly. The survival rate of eggs produced through spawning is low and the rate of fertilization of gametes is also very low. So, huge gametes can be produced by such animals. Many fish, amphibians and other sexual aquatic animals use external fertilization.