Maybe adult ghost shrimp ship better than cherries thats why they are raised as feeders... Its possible that ghost shrimps are easier to raise just because of the planktonic stage since they are in the water column and tiny they would be very easy to seperate from the adults and transfer to growout tanks. Really nothing difficult about culturing "green water" to feed the really small critters =P The ghost shrimp having smaller babies suggests they may have more of them at a time?