Ocean Zones

Lesson Plan - Get It!

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The ocean is divided into five different zones.

Ocean zones are grouped according to the amount of sunlight they receive. As the amount of sunlight decreases, temperature also decreases and pressure increases. Therefore, each zone is characterized by different organisms that are able to survive the zone's temperature and pressure.

Ocean zones have scientific names and common names. Look at the image of the ocean zones below. It lists the scientific names and the common names second.

• Which names do you prefer to use?

Tell your teacher or parent.

The epipelagic zone is located at the water's surface. For this reason, it is called the sunlight zone.

The epipelagic zone extends from the surface to around 600 feet below the surface. The temperature of the sunlight zone can vary depending on the region of the world and the depth of the zone.

The majority of marine life resides in this zone. You can easily find fish, turtles, plankton, and jellyfish floating through the epipelagic zone. The majority of plant life also lives in this zone because there is ample sunlight present for photosynthesis to occur.

The mesopelagic zone comes after the epipelagic zone. This zone is also called the twilight zone.

The mesopelagic zone starts around 600 feet deep and extends to around 3,300 feet deep. While some sunlight reaches the twilight zone, it is not enough for photosynthesis to occur, making it difficult for plants to survive in this region.

Organisms that exist in this region are swordfish, cuttlefish, and squid. Many organisms in this zone rise up to the epipelagic zone to feed at night.

The bathypelagic zone is also referred to as the midnight zone and the dark zone.

This zone is nicknamed the midnight and dark zone because sunlight does not reach this zone. The bathypelagic zone is located 3,000 to 13,000 feet below the surface, and the average temperature is about 39 degrees Fahrenheit.

Eels, squid, and mollusks live in the dark zone. It is difficult for most fish to survive in the bathypelagic zone because of the cool temperatures and lack of sunlight. Fish that do live in this zone have slow metabolisms that help them conserve energy.

There are no known plants in the midnight zone. It is believed plants cannot survive in the region because sunlight is needed for photosynthesis to occur.

The abyssopelagic zone follows the bathypelagic zone. The abyssopelagic zone is also referred to as the abyss zone.

This layer begins at around 13,000 feet and extends to the ocean floor, which is more than 19,000 feet deep. The temperature is constantly at or below freezing, and few organisms are able to survive the frigid temperatures and crushing pressure.

Some creatures that live in this zone, such as the sea cucumber, do not have eyes, because the zone is already pitch black and they do not need eyes to see.

The final ocean zone is the hadalpelagic zone.

This is the ocean water that extends below the ocean floor, deep down into ocean trenches. For this reason, the zone is also referred to as the trench zone.

Ocean trenches can range from 24,000 to 36,000 feet deep. Little is known about the hadalpelagic zone because it is so deep, making it difficult for scientists or any type of machine to venture to its depths. The pressure in this zone is more than eight tons per square inch!

The temperature and pressure make it impossible for most organisms to survive in the hadalpelagic zone, but scientists have discovered small single-celled organisms residing there.

Each ocean zone is characterized by unique temperatures, organisms, and features. Scientists know some information about each of the zones, but there is still so much to be discovered!

It is believed there are all sorts of undiscovered creatures residing in the deep zones of the oceans.

To learn more about each of the zones, read What are Ocean Zones? from Extreme Science. Be sure to click through all five zones. When you are finished reading, tell your teacher or parent what layer(s) most interest you and why.

Sail on over to the Got It? section to explore the ocean zones and learn more about the creatures that inhabit each zone.