In my previous post I mentioned the term euphotic zone and perhaps not everyone might know what this is and/or means. Which made me think that perhaps I should ‘’try’’ to explain and dive into the terminology of our oceans. As the oceans are a bit more than just a salt water body that covers over 70% of our planet. Because our planet exists for 70% of water, I decided to dive more into how the ocean works through this series I called planet Oceanus. I know that this is a complex subject and it has been some time since I have looked into the subject of oceanography. But this blog is of course a learning exploration of our seas and oceans.
You might be wondering why I would write about the terminology of the oceans, well I felt this might be a good place to start to feel more comfortable about the ocean before we dive into, the various marine habitats, ocean circulation and the effect the ocean has on our climate.
Oceanography is the science of the ocean where oceanographers look at the physical, chemical, geological and biological characteristics of the ocean. Before I dissect the terminology of the ocean with the help of the graph of the oceanic divisions, firstly talk about the term the ocean. The ocean: a large body of salt water that covers 70% of the earth. Technically there is just one ocean, as all the oceans and seas are interconnected. There are five separate ocean basins: the Arctic Ocean, the Atlantic Ocean, the Indian Ocean, the Pacific Ocean and the Southern Ocean. Know you might be wondering what is the difference between the sea and the ocean. Seas are smaller than the ocean and are located where land meets the ocean. Most of the time a sea is partially surrounded by land and is relatively shallow with a maximum depth of 200 meters. The rest of this salt water body, that is not surrounded by land and deeper than 200m is the ocean.
Now let’s dive into the ocean and start at the beach, the intertidal zone to be exact, this is the zone where we can find the tides of high water and low water. The zone between the high and low water is called the littoral. The first water zone is the Neritic this is the shallow zone of the sea with a maximum depth of 200m (meters). When the depth of the sea is deeper then 200 the sea becomes Oceanic. The oceanic zone has been divided into five layers known as zones. The first zone is the epipelagic zone or the sunlight zone, this is the upper part of the open ocean and has a max depth of 200m. Neritic and the epipelagic zone both form the photic or euphotic zone, this is the zone where there is enough sunlight to allow photosynthesis. The warmth of the sun is responsible for the temperatures of the water in this zone.
These first 200m of the ocean is also the part where most sea creatures live and where you can find the most marine habitats. These marine habitats are mostly found in the neritic including, coral reefs, seagrass meadows, sandy & rocky shores, salt marshes, mangroves and kelp forests.
The second oceanic zone is the mesopelagic zone or the twilight zone. This zone starts from a depth of 200m until a 1000m. Only a small amount of sunlight can penetrate into this zone, the mesopelagic zone is also the start of the aphotic zone, which means no more sunlight from this zone until the ocean floor. The third zone is the Bathypelagic zone also known as the midnight zone, this is where the deep sea begins. In this zone the only light that can be found is produced by organisms through bioluminescence. This is also the zone where the deep diving cetaceans such as the sperm whale and beaked whales can reach in search for food. The fourth zone is the Abyssopelagic zone also known as the abyss. This zone extends to 6000m and for a large part (3/4) of the ocean, this is the ocean floor. The fifth and deepest zone is the hadalpelagic zone, this zone extends from 6000m to the ocean floor in the deepest part of the ocean, the trenches. The deepest point of the ocean is 10.911m in the Mariana trench in the pacific ocean.
This was a short introduction into the terminology of the oceans, hopefully this will help in the understanding of other planet Oceanus subjects to come.
Sources:
Book: Invitation to oceanography, sixth edition by Paul R. Pinet
https://en.wikipedia.org/wiki/Oceanic_zone (ocean divisions graph)
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