Crayfish tolerate a wide range of salinity and water temperatures, and the crustaceans live under submerged rocks and logs in freshwater ponds, lakes, streams and rivers. Two sub-species of crayfish live in the Northern Hemisphere, and one lives in the Southern Hemisphere.
Crayfish also live in swamps, rice paddies and ditches, and have their most abundant populations in streams with acidic water. They cannot tolerate water containing human-introduced pollutants. Their diets usually consist of aquatic plants, tadpoles, amphibian eggs and small fish, and they eat small birds and animals if given the opportunity. Young crayfish eat primarily animal food sources, while adult crayfish eat primarily plant food sources.