The first blank can be filled with the pelagic zone and the second blank can be filled with the intertidal zone.
The pelagic zone comprises the water column of the open ocean and can be further differentiated into the regions by depth. Dolphins are witnessed in the pelagic zone of the ocean. The intertidal zone also called littoral zone, refers to the region of the seabed and foreshore, which comes into contact with the air at low tide and submerged at high tide, shorebirds and crabs are witnessed in this zone.