Zones of the ocean? Who lives there?

Scientists have divided the ocean into five main layers. These layers, known as zones, extend from the surface to the most extreme depths where light can no longer penetrate. The ocean is divided into various zones to help us better understand what is happening. Some of these zones help us to understand the environment in that location, others help us understand which creatures live in which parts of the ocean. Some zones are established to help us better predict conditions within them. These deep zones are where some of the most bizarre and fascinating creatures in the sea can be found.

As we dive deeper into these largely unexplored places, the temperature drops and the pressure increases at an astounding rate. Plants are found only in the sunlit zone where there is enough light for photosynthesis, however, animals are found at all depths of the oceans though their numbers are greater near the surface where food is plentiful. Still, over 90 % of all species dwell on the ocean bottom where a single rock can be home to over ten major groups such as corals, mollusks and sponges. Our sun is the major source of energy for our ocean. It is not, we have discovered, the ONLY source of energy, but it is certainly a big deal. Three temperature zones in our ocean have been identified. Each zone has a different set of conditions within it and is populated by creatures that have different needs.

Epipelagic Zone - The surface layer of the ocean is known as the epipelagic zone and extends from the surface to 200 meters (656 feet). It is also known as the sunlight zone because this is where most of the visible light exists. With the light comes heat. This heat is responsible for the wide range of temperatures that occur in this zone. In this zone, phytoplankton, which are algae and microscopic plants, live. They are the primary producers of the ocean, the lowest level on the oceanic food web. Using the process of photosynthesis, they convert carbon dioxide, water, and other nutrients to the simple carbohydrates, providing food for themselves and for higher organisms.

Mesopelagic Zone - Below the epipelagic zone is the mesopelagic zone, extending from 200 meters (656 feet) to 1000 meters (3281 feet). The mesopelagic zone is sometimes referred to as the twilight zone or the mid-water zone. The light that penetrates to this depth is extremely faint. It is in this zone that we begin to see the twinkling lights of creatures. A great diversity of strange and bizarre fishes can be found here. In the mesopelagic zone, a number of organisms survive by spending daylight hours within this zone and then rising toward the surface during evening hours. In this way, they can feed off the phytoplankton and zooplankton available near and on the surface of the water while avoiding predators during the day. The most common organisms found in the mesopelagic zone are small fish, squid, and simple shellfish.

Bathypelagic Zone - The next layer is called the bathypelagic zone. It is sometimes referred to as the midnight zone or the dark zone. This zone extends from 1000 meters (3281 feet) down to 4000 meters (13,124 feet). Here the only visible light is that produced by the creatures themselves. The water pressure at this depth is immense, reaching 5,850 pounds per square inch. In spite of the pressure, a surprisingly large number of creatures can be found here. Sperm whales can dive down to this level in search of food. Most of the animals that live at these depths are black or red in color due to the lack of light.

Abyssopelagic Zone - The next layer is called the abyssopelagic zone, also known as the abyssal zone or simply as the abyss. It extends from 4000 meters (13,124 feet) to 6000 meters (19,686 feet). The name comes from a Greek word meaning “no bottom”. The water temperature is near freezing, and there is no light at all. Very few creatures can be found at these crushing depths. Most of these are invertebrates such as basket stars and tiny squids. Three-quarters of the ocean floor lies within this zone. The deepest fish ever discovered was found in the Puerto Rico Trench at a depth of 27,460 feet (8,372 meters).

Hadalpelagic Zone - Beyond the abyssopelagic zone lays the forbidding hadalpelagic zone. This layer extends from 6000 meters (19,686 feet) to the bottom of the deepest parts of the ocean. These areas are mostly found in deep water trenches and canyons. The deepest point in the ocean is located in the Mariana Trench off the coast of Japan at 35,797 feet (10,911 meters). The temperature of the water is just above freezing, and the pressure is an incredible eight tons per square inch. That is approximately the weight of 48 Boeing 747 jets. In spite of the pressure and temperature, life can still be found here. Invertebrates such as starfish and tubeworms can thrive at these depths.

There are two general types of plants found in the ocean, those having roots that are attached to the ocean bottom and those not having roots, which simply drift about with the water. The rooted plants in the ocean are only found in shallow water because there is not enough sunlight to sustain photosynthesis in deeper waters. Since sunlight does not penetrate more than a few hundred feet into the ocean, most of the ocean is not capable of supporting rooted plants. Nevertheless, plants are found throughout most of the oceanic surface waters. The most abundant plants in the ocean are known as phytoplankton. These are usually single-celled, minute floating plants that drift throughout the surface waters of the ocean.

A bucket of seawater might hold a million microscopic diatoms, which are relatives of seaweed encased in glassy boxes. To grow, phytoplanktons need nutrients from the seawater and lots of sunlight. The most light occurs in the tropics but nutrients there, especially nitrogen and phosphorus, are often in short supply. When large quantities of diatoms and other phytoplankton are present they give a color to the sea. Spectacular phytoplankton blooms are found in cooler waters where nutrients are brought up from the sea floor during storms. The sea is home to billions of plants and animals.

Marine animals are divided into three groups: zooplankton, nekton, and benthos. Zooplankton are drifting animals and are usually small, however, they can grow to fairly large size. For example, the jellyfish and the Portuguese man-of-war are examples of larger types of zooplankton, which are unable to propel themselves and are therefore at the mercy of either wind or current. The zooplankton population also includes some temporary members such as fish eggs or larval forms of organisms, which may grow up and leave the plank-tonic community to join the nekton or benthos. Nektons are the free swimmers and probably the largest portions of familiar animals that are found in the ocean belong to this class. Common fishes, the octopus, whales, eels and squid are all examples of nekton.

The nekton category includes a number of very diverse creatures. The whale, dolphin and porpoise are certainly very different from codfish or trout because whales represent sea mammals whereas cod are true fishes. The third type of sea animal spends its entire life on or in the ocean bottom. This group of marine animals is called the benthos. It includes lobsters, starfish, various worms, snails, oysters and many more. Some of these creatures, such as lobsters and snails, may be able to move about on the bottom but their lifestyle is so bound up with the ocean floor that they are unable to survive away from this environment.

The ocean is such a wild subject. If you were to dive into the ocean, you would be able to see many creatures and plants. But there is so much more! In the ocean, there is still so much to discover. I bet even if we were to search for forever we wouldn’t be able to discover all that the ocean has to discover. If I had the chance, then I would become a professional diver or something of the sort. I would do it to discover other things, and not for the money. Try diving some time, you never know what you will discover!!