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Epipelagic Zone [Sunlight]
This zone has the depth of about 200 meters (656 feet) below the ocean surface. Microscopic plants called phytoplanktons are present in this zone. Sunlight penetrates this zone which facilitates the process of photosynthesis.

Supported Plant Species: Seaweed or free-floating algae, red algae, green algae, brown algae, phytoplankton, angiosperms, mangroves, seagrass.

Supported Animal Species: Bigeye tuna, dolphin, orcas, blue whales, sharks, jellyfish, sea turtles. The two main type of fish in this zone are forage and predator fish. Predator as well as forage fish are mostly spindle-shaped, having large mouths, smooth bodies, and bifurcated tail. Most of the fish in this zone have a sleek body.

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The Epipelagic Zone informally known as the Sunglight Zone, is from the surface of the water to about 200 meters. It has the most visbile light, and the most heat of all the layers of the ocean. It ranges from 27 to 207 degrees Fahrenheit. This is the only zone that has enough light for photosynthesis. Therefore this is the only zone that has plants.
Some organisms in the Sunlight Zone are sharks. Sharks have no bones, just cartilage. They range from 7 inches long to 50 feet long and most sharks have streamlined bodies that can help them easily go through the water. Bottom-dwelling sharks have flat bodies that help them hide in the sand. Sharks can have up to 3,000 teeth at one time with 5 rows of teeth. They need all these teeth because they’re carnivores.
Another type of fish in the Sunlight Zone is the Angelfish. There are about 70 different species. They are all brightly covered and live in reefs in warm waters. They range froom 12-15 inches long. They are carnivores.
Oysters also live in the Sunlight Zone. They ahve a soft body between two hard shells that are attached by a muscle. The largest oysters are three feet long. However, they can be as small as only a few inches long. They actually change genders. They begin as males and turn into females.

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Mesopelagic Zone [Twilight Zone]
This zone extends from epipelagic zone at about 200 meters (656 feet) to a depth of about 1000 meters (3,280 feet). Sunlight penetrates to a very little extent, which makes the process of photosynthesis impossible.

Supported Plant Species: No plants exist in this zone due to lack of light.

Supported Animal Species: Squid, crab, cuttlefish, lancetfish, chain catshark, swordfish, wolf eels, bigeye tuna, calm, gastropods, krill. Most of the fish in this zone are highly mobile with scaled, muscular bodies and rigid bones. They have big kidneys and hearts. Their gills (respiratory organ) are well-developed.

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The Mesopelagic Zone, also known as the Twilight, or Midwater Zone, is the second ocean zone. It is from 200 meters down to 1000 meters down. There is not much light, but there is enough to see during the day. Many of the animals in this zone have bioluminescence. This is when a fish has a certain chemical that creates light to help them see. There is not enough light for photosynthesis so the organisms have to eat food that is filtered down from above. There are filter feeders, grazers, and predators.
One type of fish that lives in the Twilight Zone is the viperfish. It has a large mouth with teeth that don’t fit in it’s mouth. It’s mouth is hinged so they can open it as wide as they want. It uses bioluminescence. It is about 11 to 12 inches long.  They are dark, silvery blue. They are eaten by sharks and some dolphins.
There are about 45 different species of the hatchet fish. Ther range from 1 to 6 inches long. Most types have silvery scales. Most of these fish do not live for more than a year.
The eel is a boney fish with a snake-like body. Some live in salt water, and others live in fresh water. They hatch from eggs that are laid by their mother. They migrate to breed and eat.
The cuttle fish has a soft body with eight arms. They have two tentacles. Their skin color and pattern changes. They only live for about 18 months. Cuttlefish are about one foot long and eat small mollusks, worms, crabs, and shrimp. They are eaten by sharks, fish and other cuttlefish.

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Bathypelagic Zone [Midnight Zone]
This zone extends from mesopelagic zone at about 1000 meters (3,280 feet) to a depth of about 4000 meters (13,123 feet). Sunlight doesn’t penetrate in this zone. This region is very low on nutrient levels.

Supported Plant Species: No plants exist in this zone due to lack of light.

Supported Animal Species: Squid, sea stars , large whale, octopus, viperfish, frill shark, echinoids. Most of the fish have low metabolism rate as the zone lacks in nutrients. The fish have tiny eyes, fragile skin, faint muscles, and a slimy body.

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The Bathypelagic Zone, informally known as the Midnight Zone, is 1,000-4,000 meters deep, resulting in a total absence of sunlight. Bioluminescence, light produced by organisms, is the only source of light. Food is scarce. Only 5% of food from the Epipelagic Zone reaches the Bathypelagic Zone. Most organisms of the Midnight Zone either are “sit and wait” predators or attract their prey with their bioluminescent lights, such as the female angler fish, who injest their prey in the inrush into the angler’s mouth when the angler fish opens its mouth. Many Deep-Sea organisms will eat anything that comes their way. These organisms tend to be black, red, or transparent, which makes them almost invisible in the total darkness. Bathypelagic Organisms include

Bristlemouths, Deep-Sea Angler Fish, Slickheads, Gulper Eels, Humpback Anglefish, and Phantom Anglefish. Bathypelagic fish tend to have huge mouths and long jaws to help them swallow anything and everything that comes their way. In addition, they have many teeth.

Some Bathypelagic fish are hermaphroditic, so that an encounter with any fish will produce results. Most of these organisms use bioluminescence to attract each other. Female angler fish release pheromones for the male anglers to hone in on. The male bites into the female tissue and never lets go. The male’s circulatory system joins the female’s and the male’s body degenerates until he is only a sack of testes.

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The Abyss, also called the Abyssopelagic or Abyssal Zone lies in perpetual darkness. The name is Greek-based and means “bottomless”. It is from 2,000-6,000 meters. Because water pressure increases one atmosphere every 33 feet in depth, animals in the abyssal zone must be able to withstand tremendous amounts of pressure. Its waters are near-freezing at 2-3° C. This layer is low in oxygen, food, and nutrients. In the Abyss live the deep water squid is completely transparent and has photophores on its tentacles to attract food and scare away predators. Basket stars sit on the sea floor or attach themselves to tall sessile animals or plants, with their flexible arms raised above them to catch floating and falling organic particles. Their arms are quite fragile, but can regenerate quickly. They have an armspan of over 25cm. Abyssopelagic oganisms include Deep-Water Squids, Basket Stars, Seapigs, Sea Spiders, Echinoderms, and Medusas. However, the most bizzare and fantastic organisms in the Abyss are tube worms, that have no mouth, no stomach, no intestines, and no excretory system. The discovery of tube worms in 1977 lead to thThe Trenches, also known as the Hadalpelagic or Hadal zone, are the deepest parts of the ocean. It is from 6000m (19,686 ft) below sea level to the bottom of the ocean. A trench is a narrow, elongate, v-shaped cavity in the ocean floor. Trenches are the deepest parts of the earth and ocean. The deepest trench in the world is the Mariana Trench off the coast of Japan. The Mariana Trench is 36,797ft (10,911m) below sea level. Trenches are formed where the oceanic plate goes below the overriding plate during subduction, a tectonic process. The trenches still remain largely unexplored because of its temperature (just above freezing) and pressure (8 tons per square inch).
Because of the freezing temperature, intense pressure, and darkness of the trenches, very few organisms live here. The few organisms that live here are adapted to the freezing temperature, are invertebrates, and some do not have eyes or indicate enough flashes of bioluminescent light to keep their eyes from fading because there is no light. Since there is no light, there are no plants. Some organisms feed on dead bodies of other organisms who live in above zones and other things that fall down to this zone. Some examples of organisms that thrive down here are; polychaete worms, brotulids, sea cucumbers, Foraminifera (tiny one celled organisms, a type of plankton) and Pale white hadal snailfish (Pseudoliparis amblystomopsis).
e creation of a new class in the animal kingdom: vestimentiferans. Before tube worms were discovered, it was thought that all organisms lived off the sun’s energy. Tube worms are the first and only creatures found that live off something other than sunglight. Through a process called chemosynthesis, tube worms are able to flourish, as well as allow other organisms to exist in the the harsh climate as well. Vent species rely not on sunlight, but on chemicals from the Earth’s interior. Tiny microbes oxidize the hydrogen sulfide that diffuses out of the vents, providing nutrients for animals higher up the food chain. Chemosynthesis allows over 300 vent species to exist. 95% of these organisms were new to science before of the discovery of the tube worm.

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