The Ocean Zones

The ocean covers more than 70 per cent of the Earth’s total surface and contains roughly 97 per cent of all its water. Measuring about 361.9 million square kilometers, it is a massive continuous body of salt water, so large in fact that oceanographers estimate that less than 20 per cent has been explored.

Ocean sunlight zone

Aptly named for its position at the surface level, this sunlight zone, also called the surface zone or epipelagic zone, extends downward 200 meters or roughly 5 per cent of the ocean’s average depth. At midday, it is practically fully lit by the sun, hence called the sunlight zone. It is also regarded as the warmest layer. An abundance of natural light also generates heat, which penetrates deeper waters due to the movement of the wind. Depending on location, the temperature of the epipelagic zone can go as high as 97 degrees Fahrenheit or drop as far 28 degrees .Enough sunlight penetrates this layer for algae to utilize photosynthesis, which in turn creates roughly 50 per cent of the oxygen in our atmosphere.

Ocean twilight zone

The twilight zone or the mesopelagic zone begins at 200 meters and extends downward to 1,000 meters, making up approximately 20 per cent percent of the ocean’s total depth. It is generally a very dim region, but it does receive a sliver of sunlight at the midday point which is enough for photosynthesis to occur. The twilight zone actually plays a large role in regulating our planet; the ocean absorbs roughly 25 per cent of the carbon dioxide humans emit and pushes it down to the deep ocean, preventing it from rereleasing into the atmosphere. Unlike the surface zone, this second layer has remained relatively untouched from commercial fishing despite the fact that it is bursting with aquatic life.

The deep ocean

The deep ocean—the third and final layer—extends from the 1,000 meter point to the ocean floor, regardless of how deep that is. At minimum, it makes up 75 per cent of the ocean’s depth. It is a frigid region that receives absolutely no natural light. The organisms that live in this zone are bioluminescent; that is to say they produce and emit their own light. Examples of these creatures include certain types of plankton, jellyfish, squid, and the nightmarish barbeled dragonfish. Living in complete darkness, they have light-sensitive eyes that allow them to sense each other’s presence.

Ocean midnight zone

The midnight zone is also known as the bathypelagic zone makes up the first third of the deep ocean in the three layers model. It extends downward from 1,000 meters to 4,000—roughly the average depth of the global ocean. The temperature rarely changes, remaining at a fairly consistent 39 degrees Fahrenheit. As mentioned earlier, the only light in this regions does not come from the sun, but from bioluminescent animals who use their ability to hunt or find a mate.

The abyss

The abyss (abyssopelagic zone) is the middle layer of the deep ocean. Its name comes from the Greek word abyss which means “no bottom.” True to its name, there was a time when the ancients believed that the ocean was a bottomless void. It extends from 4,000 meters down to 6,000, which for some global regions marks the seafloor.

The trenches

The trenches (hadalpelagic zone) is the deepest part of the ocean. It extends past the abyssopelagic zone in parts of the world where that is physically possible; this is usually in the form of deep sea trenches and canyons.

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