Answer:
Open ocean of any depth, where animals swim or float freely, is called: pelagic zone.
Step-by-step explanation:
Open ocean of any depth is called pelagic zone or open ocean zone. This zone can be assumed as water column or cylinder that goes from the bottom of the sea to almost surface.The mean depth of any pelagic zone is almost 3.68 to 11 kilometers.
In this region, the temperature and pressure may vary as we go from top to bottom of the zone of any depth however, the zone is called same pelagic zone.
This is because while going from top to bottom of ocean the light penetration becomes less, this causes a drop in the temperature of ocean. Therefore, the atmosphere of ocean can further be subdivided into different zones based on the factors like pressure and temperature.
Hope it helps!