Shrimp use external fertilization. This is usually performed in an aquatic environment, by spawning, where eggs and sperms are released into the water in the same area. Once the sperm reaches the egg, fertilization can occur. The release of the reproductive material may also be triggered by water temperature of the length of daylight. External fertilization in an aquatic environment protects the eggs from drying out. By broadcast spawning, there becomes a greater mixture of genes in the group, resulting in genetic diversity and better species survival in hostile areas. Female fairy shrimp can produce two (2) types of eggs, thin shelled "summer" eggs and thick shelled "winter" eggs. This is determined by the number of males in the community. A shortage of males results in the production of summer eggs.