The larval period in P. setiferus lasts 10 days or more. Perez-Farfante (1969) reported 5 naupliar stages, 3 protozoeal stages, 3 mysis stages, and 2 postlarval stages before the juvenile stage is reached. The non-feeding nauplius stage undergoes 5 molts over 24 - 36 hours to the protozoeal stage which measures approximately 1 mm in length. Feeding behavior is initiated with the first protozoeal stage. Protozoea grow to a length of approximately 2.5 mm before achieving the mysis stage. Following a third mysis stage, the postlarval stage is attained.Postlarvae of P. setiferus are planktonic, gradually moving inshore to estuarine nursery grounds on tidal currents (Whitaker 1983a). Most enter estuaries as second stage postlarvae measuring approximately 7 mm in length. Upon reaching estuaries postlarvae become benthic (Williams 1965). In North and South Carolina, postlarval P. setiferus enter estuaries from June through September; in Georgia, postlarvae may enter estuaries as early as April and May. In northeastern Florida, postlarvae first begin to appear in early June.Perez-Farfante (1969) considered postlarvae to be juveniles once they had acquired 4 - 10 upper rostral teeth, and 1 to 3 lower rostral teeth.