The life cycle of brine shrimp begins with a female laying eggs in a brood sac. If she was fertilized by a male, her offspring are of both sexes; otherwise, only females result. The eggs hatch almost immediately, and the resulting nauplii mature to adulthood in one week.
Brine shrimp eggs hatch only when plenty of water is present and salinity is not too high. If the conditions are not right, the female deposits her eggs as cysts. These cysts are metabolically inactive and can remain viable for up to two years; some may be capable of hatching after 50 years. Once placed in water meeting their requirements, cysts usually hatch in a few hours, though some may need continuous hydration for at least 36 hours.