The Oceans on Earth: The oceans make a world by itself within the world where we live. There are five major oceans on our planet which includes the Atlantic, the Pacific, the Indian, the Arctic, and the Southern Oceans. We will be discussing each of these oceans in different lessons, later. Anyways, by now you must be aware that over 70% of our planet’s surface is covered by oceans. Scientists believe that majority of animal and plant life in the marine biome lives in the unexplored areas of ocean (by humans).
The oceans, combined together, make a huge world. We can divide these oceans into three layers (zones). These layers are popular as light zones as the zones are classified on the basis of how much sunlight these layers receive.
Sunlight zone: Sunlight zone which is also known as the euphotic zone is the top most layer of the ocean. Naturally, being the top most, this layer receives the maximum sunlight. This layer has varied depths, but at an average it is expected to be 600 feet deep. As sunlight provides energy to organisms, it is expected that almost 90% of the ocean lives are existing in the euphotic zone.
Twilight zone: It is the middle layer of the ocean where sunlight is poor. The amount of sunlight is too less for plants to exist in this zone. Twilight zone is also known as disphotic zone which is between 600 feet to almost 3000 feet deep. The animals that live here have adapted to live in darker environment or with very little sunlight. There are also animals which produce their own light through chemical reactions.
Midnight zone: This layer is completely dark and is also known as aphotic zone. This layer starts from around 3000 feet and goes deep. The water pressure at this layer is too high and only a few animals gain adaptation to live here. It is not only the water pressure but also the coldness that makes life in this zone harsh. What makes it more interesting is that almost 90% of the ocean falls in this zone.
Now, to learn about the individual oceans click on their appropriate links – the Atlantic, the Pacific, the Indian, the Arctic, and the Southern Oceans.