Religious rites and rituals regarding food also tend to classify the birds of the air and the fish of the sea separately from land-bound mammals. Sea-bound mammals are often treated as fish under religious laws – as in Jewish dietary law, which forbids the eating of cetacean meat, such as whale, dolphin or porpoise, because they are not "fish with fins and scales"; nor, as mammals, do they chew their cud and have cloven hooves, as required by . Jewish (kosher) practice treat fish differently from other animal foods. The distinction between fish and "meat" is codified by the Jewish dietary law of "kashrut", regarding the mixing of milk and meat, which does not forbid the mixing of milk and fish. Modern Jewish legal practice ("halakha") on "kashrut" classifies the flesh of both mammals and birds as "meat"; fish are considered to be "parve", neither meat nor a dairy food. (The preceding portion refers only to the halakha of Ashkenazi Jews, Sephardic Jews do not mix fish with dairy.)