The SEM findings of the crab louse egg reveal a complicated aeropyle system within the operculum which is important for gaseous exchange and fluid retention. The SEM correlates with the first light microscope observations in the study of these aeropyle structures. These structures consist of a system of apertures that converge down from a larger opening to a smaller opening. the aeropyles and their adjacent reticulum network can be fractured in order to visualize each of the smaller openings that compose its substructure. The eggs, having been hatched, reveal structures comprising the vitelline membrane: (1) a latch; (2) an ellipsoid with two parallel rows of spikes and (3) an ellipsoid with two parallel rows of pores. The ellipsoid with spikes is the only one of these structures visible in an egg with opened operculum and intact vitelline membrane. The ellipsoid with pores and latch arise from the under surface of the vitelline membrane. The ellipsoid with pores is observed on the inner aspect of the opened egg by tilting the ellipsoid with spikes on the outer aspect of the opened egg. Both ellipsoid structures appear to be attached at the same place but on opposite surfaces of the vitelline membrane. These ellipsoid structures and latch, while covering the developing embryo beneath, appear to be involved in the hatching mechanism itself.