the four orders that make up this class include brine shrimp, tadpole shrimp, water fleas, and clam shrimp; most live in fresh water or in small, salty lakes or ponds and are small (under 2 cm); the number of segments and appendages possessed by an individual varies considerably among groups, but in most forms the number of segments is large and tagmosis is minimal; most feed by filtering small organisms and organic particles from the water.