Major Characteristics of a Pelagic Ocean

The aquatic ecosystem is the largest on the planet, and as a result of its enormity, oceanographers have divided the ocean up into zones. Creation of the zones is by oceanic characteristics, one of which is water depth. The pelagic realm is the area between the sea floor and the ocean's surface. It is in the pelagic realm that most marine life lives and finds its food. The pelagic realm is not coastal; instead, it is the area of the ocean where nothing exists but water on all sides.

  1. Pelagic Ocean

    • The pelagic ocean refers to water that is open and not near land. The ocean is cold, yet the water is a constant mix of warm with colder waters, making the exact temperature difficult to calculate. The pelagic ocean is thermally stratified, and the constant flow of warm and cold water brings a flow of flora to the area including seaweed. Fauna -- fish and mammals that eat the flora in the pelagic ocean -- can sustain their lives doing so. Plankton is also a food source found in the pelagic zone.

    Neritic Zone

    • Tuna fishing takes place in the pelagic sea.

      The neritic zone, the first 656 feet of ocean water, is part of the pelagic ocean. Carbon dioxide turns into food through sunlight and water in this part of the pelagic ocean, and phytoplankton and sargassum thrive in the neritic zone. Small marine life thrives on phytoplankton and sargassum, making the neritic zone a feeding zone for larger marine life. Schools of tuna and mackerel feed in this area on squid and krill; by feeding in this pelagic zone, a northern bluefin tuna can exceed 10 feet in length and 1,500 pounds in weight.

    Oceanic Zone

    • Whales feed in both zones of the pelagic ocean.

      The oceanic zone is the area below the neritic zone all the way to the ocean floor that does not receive the same amount of sunlight as the neritic zone. The oceanic zone has three sub-zones: the euphotic, dysphotic and aphotic zones. The euphotic zone has photosynthetic life several feet down, allowing for variations of phytoplankton and flora for feeding. The dysphotic zone does not have enough light for photosynthesis, but light is still visible. The aphotic zone is completely black and devoid of any light. Marine animals have evolved into creatures who can sustain life on the food available in this zone of the pelagic ocean.

    Zooplankton

    • Sharks, like whales, filter zooplankton from the pelagic ocean.

      Zooplankton floats in the water, and its size ranges from microscopic to small fish. Whales consume zooplankton as the major portion of their diets. By forcing seawater through their baleen plates in the front of their mouths, the whales filter the zooplankton out of the water and then eat it. Sharks also live off these sea creatures, filtering them from ocean water in much the same way.