Ocean Zones

Oceans have different parts, or zones, that help scientists figure out how deep ocean animals live. Different animals live in different zones than others, since the ocean zones have different resources. For example, animals that need light to survive live in the topmost zone of the ocean, which is the sunlight zone.

The Sunlight Zone

The sunlight zone is the topmost layer of the ocean, reaching a depth of 200 meters. The sunlight zone receives the most light, so a vast amount of aquatic animals live in it. Mammals like otters or seals need air to breathe, so they live in the sunlight zone, which is close to the air. Microscopic plankton, as well as many fish, also share this part of the ocean.

Residents of the Sunlight Zone:

Aquatic plants, sharks, seals, jellyfish, rays, small fish, etc.

The Twilight Zone

This layer of the ocean starts at 200 meters down and reaches a depth of 800 meters. The twilight zone receives very little sunlight because the seawater absorbs most of the sunlight. No sunlight-needing animals live in this section. The food is low in energy and nutrients. Animals that live here need to adapt to the darkness. They use different techniques to survive. Some species of fish here have a lantern on their heads and use this light to attract prey. Some fish are bioluminescent, which means they can generate light with their bodies! Animals in the twilight zone are truly unusual and unique.

Residents of the Twilight Zone:

Large octopuses, sperm whale, angel shark, gray whale, hatchet fish(bioluminescent), small squids, types of eels, etc.

The Midnight Zone

This zone of the ocean covers 90 percent of ocean waters. It starts at 800 meters down and reaches a depth of 4000 meters, which is the ocean floor. The waters are almost at freezing temperature, and it is pitch black. Extreme pressures from above waters make it difficult to survive. However, animals have their ways of survival. Many animals are bioluminescent to deal with the darkness.When organisms from upper levels of the ocean die, they drift down to the midnight zone. Residents of this zone feed on the dead organisms. Also, many animals that live here have soft bodies which absorb the pressures of the ocean. These pressures would kill other animals.

Residents of the Midnight Zone:

Many types of bacteria, bivalves(animals covered in two hard shells that hinge together), eels, viper fish, sharks, giant squid, etc.

Hydrothermal Vents of the Midnight Zone

Hydrothermal vents are hot springs located at the ocean floor. Hydrothermal vents shoot out warm water, which is heated by the magma under the Earth. Along with heated water, the vents also shoot out a variety of chemicals, like hydrogen sulfide. Varieties of animals live around these vents, depending on these chemicals for nutrients. Some animals, like the yeti crab, collect bacteria shooting out of these vents. The yeti crab places its amazingly long and hairy arms above a hydrothermal vent. Bacteria shooting out of the vent gets stuck in the yeti crab’s arms. The yeti crab uses these bacteria for nutrients.

The Abyssal Zone

The abyssal zone covers the deep sea trenches at the bottom of the ocean. It is the deepest part of the ocean. These trenches occur when heavy tectonic plates lie under lighter ones, causing the plates to move downwards. Very few animals live here. The waters are almost freezing, and there is no sunlight. Unimaginable pressures weigh down on this zone, but animals still survive in this death zone! These conditions make it almost impossible for humans to explore the abyssal zone. We do not know very much about the abyssal zone.

Residents of the Abyssal Zone:

Types of anglerfish, deep sea jellyfish, tripod fish, abyssal octopus, etc.