CBSE Class 10 Answered

External fertilization is a form of fertilization in which a sperm cell is united with an egg cell outside the bodies of the reproducing individuals.

External fertilization occurs mostly in wet environments and requires both the male and the female to release their gametes into their surroundings (usually water). An advantage of external fertilization is that it results in the production of a large number of offsprings. One disadvantage is that environmental hazards such as predators greatly reduce the chance of surviving into adulthood.

In many aquatic animals such as coral or hydra, eggs and sperm are simultaneously shed into the water, and the sperm swim through the water to fertilize the egg. Amphibians and fish are examples of vertebrates that reproduce this way. Many plants make use of external fertilization, especially ones without bright flowers or other means of attracting animals.