Fairy shrimp (Anostraca) are branchiopods that include brine shrimp. They often appear in vernal pools, pot holes and other ephemeral pools. Although they live in fresh or saltwater, they do not live in oceans or seas. They are well-adapted to living in arid areas where water is present for only part of the year. Their eggs will survive drought for several years and hatch about 30 hours after rains fill the pools where they live. Some eggs may not hatch until going through several wet/dry cycles, ensuring the animals’ survival through times that the pools don’t last long enough for the shrimp to reproduce. About 200 species are known.