Ocean Zones

Ocean zones are layers within the seas that contain distinctive plant and animal life. They are sometimes referred to as ocean layers or environmental zones. A system of zonation frequently used by oceanographers grew out of suggestions made by Joel Hedgpeth in 1957. According to that system, the ocean environment is first divided into two broad categories, known as realms, the benthic realm, consisting of the seafloor; and the pelagic realm, which consists of the ocean waters. Each of these realms is then subdivided into separate zones according to the depth of the water, which strongly influences the types of plant and animal life they contain.

Scientists often separate the pelagic realm into two regions, or divisions. The portion of the ocean that overlies the continental shelf, to a maximum depth of about 650 ft (200 m), is known as the neritic, or coastal, division. The portion outward from the continental shelf is classified as the oceanic division.