Field and laboratory evidence demonstrates that differences in tolerance to salinity and temperature of phyllopods notably affect their habitat types and seasonal occurrence. Oxygen concentration and pH are of lesser ecological consequence. The 11 phyllopods studied are categorized according to their seasonal occurrence and habitat salinities. For example, based on the tolerance of both eggs and adults, Branchinecta lindahli is eurythermal and euryhaline, whereas Triops longicaudatus is stenothermal and stenohaline. Though some adult phyllopods endure substantial ranges in salinity and temperature, their eggs are not necessarily so adapted. In some instances egg hatchability is impeded by environments not hostile to adult shrimp. Phyllopod eggs are, therefore, instrumental in defining when and where a particular species occurs. Ephemeral ponds with moderately high magnesium concentrations may be hostile to some phyllopods.

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Seasonal distributional patterns of five phyllopods from southwest Texas are similar to those of the same species from more northern latitudes. At both latitudes a primary environmental cue controlling the appearance of phyllopods seems to be temperature. For instance, in Texas Branchinecta packardi was the only cold water species. In addition to the effects of temperature on phyllopod zoogeography, diurnal studies show that high temperatures contribute both directly and indirectly to oxygen depletion in temporary ponds. The comparative tolerance of phyllopods to near anaerobic conditions was as follows: calm shrimp, Caenestheriella setosa > tadpole shrimp, Triops longicaudatus > fairy shrimp, Streptocephalus texanus.

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