1) Environmental hazards: When fertilization occurs outside the body, the eggs and sperms are exposed to various environmental factors that can affect their viability. These factors include temperature fluctuations, predation, and exposure to harmful substances. Producing a large number of eggs increases the chances that some will survive and develop into offspring despite these challenges.
2) Lack of protection: Unlike internal fertilizers, where the eggs are protected within the female's body, eggs fertilized externally are more vulnerable to predation and damage. By releasing a greater number of eggs, the species increase the likelihood that some will escape predators and survive to adulthood.
3) Low fertilization success: External fertilization relies on the sperms to find and penetrate the eggs in the external environment. This process can be inefficient, and many sperms may fail to reach or fertilize the eggs. To compensate for this lower fertilization success rate, animals producing large number of eggs ensure that at least some will be successfully fertilized.
4) Competition: In species with external fertilization, competition among offspring for resources is intense. Many eggs may not survive due to limited food availability or suitable habitats. Producing more eggs increases the chances that some offspring will find sufficient resources and survive.
5) Evolution and survival strategies: The tendency to produce more eggs in external fertilization has evolved over time as a survival strategy for the species. Those that produced a larger number of eggs had a better chance of reproductive success and passing on their genes to the next generation.
While internal fertilizers may produce fewer eggs, they have the advantage of providing a more protected and controlled environment for the developing embryos. This strategy reduces the need for producing large numbers of eggs and allows for more efficient use of resources.