External fertilization

External fertilization is a form of fertilzation (e.g. in plants or animals) in which a sperm cell is united with an egg cell outside of the body of the female of the species. Thus, the fertilization is said to occur "externally". This is distinct from internal fertilization where the union of the egg and sperm occur inside of the female.

In sexual reproduction, there must be some way of getting the sperm to the egg. Since sperm are designed to be motile in a watery environment, aquatic animals can make use of the water in which they live. In many aquatic animals such as coral, eggs and sperm are simultaneously shed into the water, and the sperm swim through the water to fertilze the egg. Many fish, such as salmon, the female will lay unfertilize eggs and the male will swim by and fertilize them.

References

• University of Cincinati Clermont College