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Why do Most of the Living Organisms In the Ocean Live In the Top Layer?

Updated on July 5, 2015

Layers of the Ocean

Epipelagic Zone

The oceans are home to billions of animals and plants and most of these plants and animals live in the epipelagic part of the ocean because of sunlight and the process of photosynthesis. There are a total of five layers. The epipelagic zone is the very first layer of the ocean and in this zone lives 90% of all the life in the ocean. Most of you may already know that much of the life in the ocean requires warmth and sunlight, which is the reason why most of the marine life in the oceans live in or near the epipelagic zone.

Photosynthesis plays a huge part in producing food for marine life that live in the upper, middle and bottom layers of the ocean because it produces some carbon and lots of oxygen, which in turns helps plants to produce food that all animals in all zones of the ocean are able to feed off of. The plants in the ocean are called the producers because they make their own food through photosynthesis and the animals are called consumers because they consume the producers.

Mesopelagic, bathypelagic, abyssopelagic and hadalpelagic are the other layers of the ocean. The living organism that live in the mesopelagic zone are bioluminescent, meaning that they give off a shimmering light. Because this zone extends almost 3,281 feet below the surface of the ocean, the sunlight in this zone is very faint. The bathypelagic zone extends 13, 124 feet below the surface of the ocean and sunlight is nowhere to be seen. However, there is light that comes from the creatures at this depth and the water pressure in this zone is very immense and can reach 5,850 pounds. This amount of pressure would be like having a Great White Shark on dry land lying on top of you. There is a large number of marine life that resides in this layer despite the immense pressure and darkness such as: sperm whales, the vampire squid, snake dragonfish, angler fish and many more. The abyssopelagic zone aka "the abyss" is 19,686 feet below the surface of the ocean. This zone has freezing temperatures, no light and little marine life. The life that can be found in this zone would be invertebrates. Invertebrates such as jellyfish, worms, mollusks, arthropods, etc....have no skeleton, which means that they are boneless. Last, but not least there is the hadalpelagic zone. This zone is referred to as "Hades". It extends 35,797 feet below the surface of the ocean or even lower. 35,797 feet is the depth in which a human has been able to travel much like the universe; the ocean has not been fully explored. The hadalpelagic zone is the deepest part of the ocean and can only be reached through trenches and canyons in the ocean. The temperature is a little above freezing, pressure is excruciating, weighing in at 8 tons and has life such as the giant tube worm, starfish, eel, blowfish, etc... Animals at this depth are referred to as "Benthos" .

Benthos animals are among the few animals that are able to survive on the bottom of the ocean. This is mainly because these animals have learned to adapt to living in low light and high pressure conditions. All of the animals that live on the bottom of the ocean do not need sunlight. This would explain the reason why there are not so many animals that live on the bottom of the ocean. Most marine animals need sunlight to live and grow. The animals that do exist at the bottom of the ocean are limited to food. There is no light at the bottom of the ocean so photosynthesis is not able to take its course and plants cannot produce food. These animals have to wait patiently for food to fall down from animals from the upper zones of the ocean.

© 2012 Shakka James


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    • Shakka James profile image

      Shakka James 2 years ago from Dallas, TX


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      Jennifer gold 2 years ago

      Awesome videos

    • MarleneB profile image

      Marlene Bertrand 5 years ago from Northern California, USA

      You are off to a wonderful start. Your hubs are quite enjoyable to read. I am happy to be following you because I love to read excellent writers. Keep 'em coming!

    • Shakka James profile image

      Shakka James 5 years ago from Dallas, TX

      Thank you for your reply, I just started and also trying to get the hang of things. I am pretty sure the more I practice the better I will become. I hope to post some more stories that interest you!

    • MarleneB profile image

      Marlene Bertrand 5 years ago from Northern California, USA

      I found this fascinating. I never realized the intricacies of the different layers before now. But, with regard to light and pressure, it makes a lot of sense. The video is an excellent representation of the information in the hub. Thank you for sharing it with us.