Identify four factors that divide the oceans in different zones of life.

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trophyhunter1 eNotes educator| Certified Educator

The upper zone in the ocean is known as the euphotic zone and as its name indicates, is bathed in light. Depending on how clear the water is, it can extend to about 660 feet in depth. Here you will find an enormous amount of different algae, as well as flowering plant producers such as sea grass. These producers capture sunlight and convert it to food energy, which is the backbone of the euphotic zone food chains. Living here are fish, sea-turtles, Cnidaria, coral, seals, Echinoderms. The dysphotic zone is next, extending to about 3300 feet and although it receives a little light, no photosynthesis occurs here. The next zone is the midnight zone or aphotic zone, a zone of no light. It can extend to 20,000 feet. It is in this zone that food chains are not dependent on photosynthetic activity. Rather, chemosynthetic bacteria use chemicals as a means of obtaining energy and food chains usually involve debris that sinks down to this zone from above. Many creatures living here are bioluminescent, giving off a glow from chemicals within their cells. Creatures here must be able to deal with extremely cold temperatures and high pressure. The factors dividing the ocean into these various zones are sunlight, photosynthesis, pressure, temperature, availability of food.