How the Ocean Sustains Complex Life

Hundreds of illustrations depicting the same vertical profile of the sea can be found online. The sunlight or epipelagic zone is the thin, top layer and receives enough light to produce food. The twilight zone is where the light fades but is still strong enough for some animals to see. Next is the midnight zone with no light. The hadal zone is named after the Greek god of the Underworld.

The amount of light and the water pressure determine which animals live where. The factors that are important are water temperature, salinity, amount of oxygen and nitrogen, and the changing currents. Ocean life and ocean dynamics are far more complex than we thought, and have been for a long time.