Fairy Shrimp are found in temporary waters such as vernal pools, marshes, wetlands, and ditches. They survive during dry periods by remaining as thick-walled eggs that can withstand drought for many years. There are up to 17 pairs of appendages (gill legs) located on the abdomen of the fairy shrimp and these are used both for filtering food and for respiration. Fairy shrimp use their appendages for swimming slowly on their backs while collecting food.

We find fairy shrimp mostly in winter, particularly in the water in wooded areas. Many of these animals have egg cases attached to the abdomen. The ones photographed were found in January and are one-and-a-quarter inches long. The species is probably E. vernalis. Some years we find no fairy shrimp, but their populations are known to vary.

Females can produce two types of eggs. Thin-shelled "summer eggs" are be produced if there is a shortage of males in the population. These eggs hatch rapidly and the young develop during the same season they are laid. They can complete their life cycle in less than two-and a half weeks.

Thick-shelled "winter eggs" stay in the mud at the bottom of the water and, if the area dries out, they will not hatch until the area becomes wet again (usually the following spring). The usual dormant phase for the eggs is 6 to 10 months, and they usually hatch 30 hours after being exposed to water. In the laboratory, eggs have been hatched after 15 years dormancy and also after being subjected to temperatures ranging from -190 C to 99C. Winter eggs, because they are so hardy, can be spread to other areas by animals or even by the wind.