The leg movements serve the purpose of collecting algae, bacteria, protozoa, rotifers and floating detritus from the water. Food is then filtered from the water and scraped by sets of appendages to be eaten using a mandible mouth. Fairy shrimp have been observed gnawing on larger matter such as dead tadpoles, mollusks and amphibian eggs. The leg movements of the fairy shrimp also serve the purpose of taking the oxygen the animal needs from the water. The ephemeral nature of the fairy shrimp reduces the limiting factors on their population.
Fairy shrimp have few natural predators.
They are unlikely to be heavily preyed upon by other vernal pool inhabitants because they utilize the pool before the majority of carnivorous insects have colonized the pool. Also, the wood frogs and mole salamanders breeding in the pools have not regained their regular appetite after winter hibernation and, thus, are not major predators. However, these amphibians, caddis fly larvae, dytiscid larvae, other insects, and, especially, waterfowl who utilize the pool, often do prey upon fairy shrimp. Because fairy shrimp live in temporary wetlands there are no predatory fish. The abundance of food is less of a factor in the population of fairy shrimp than in other organisms.