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Microphotograph of typical benthic animals

The Benthic Zone is the lowest level of a body of water such as an ocean or a lake. It is inhabited by organisms that live in close relationship with (if not physically attached to) the ground, called benthos or benthic organisms. Generally, these include life forms that tolerate cool temperatures and low oxygen levels, but this depends on the depth of the water. For information on animals that live in the deepest areas of the oceans see aphotic zone. The superficial layer of the soil lining the given body of water is an integral part of the benthic zone, as it influences greatly the biological activity which takes place there. Examples of contact soil layers include sand bottoms, rock outcrops, coral, and bay mud.

When looked at from this perspective, the body of water would then have another realm, the pelagic zone, which includes all that lives associated to the water column.

Benthic means anything associated with or happening on the bottom of a body of water. The Benthic Zone of the ocean is the bottom ocean zone ranging from the deepest parts of the ocean to the tidal affected areas. The most productive region of the benthic zone is the area over the continental margin, which is unaffected by the tides.

The Benthic Zone’s organisms are different from the ones on the other parts of the ocean. They are called benthos. They have a different body structures and different physical appearances than that of the other parts of the ocean. In their habitats they can be considered as dominant creatures.

These benthos cannot live on the upper parts of the ocean and they cannot be brought up to the surface, because if they leave their territory and try to go somewhere else, they will die due to the difference in pressure of the water (water pressure increases one atmosphere for every 33 feet of depth.)

Because they live in deep places, their main food is dead and decaying matter. So, the organisms in the Benthic Zone are scavengers.

The Benthic Zone's habitats are divided into zones based on depth. From the shallowest to the deepest are: the estuarine zone — less than 200 meters; then the bathyal zone — 200-2000 meters; the abyssal — 2000-6000 meters; and the deepest, the hadal zone — over 6000 meters.

All these zones are in deep, pressured areas of the ocean. Because of the high pressure and seclusion neither tidal changes nor human interference has had much of an effect on these areas, and the habitats have not changed much over the years. Most Benthos have the same physical appearances and the same body structure as their ancestors about one million years ago. The only drastic change has been body size, e.g., the organism was 15 feet then and now it might only be about one or two feet.

Humans are not able to map or observe these organisms and their habitats very well, and most observation has been done through remote controlled submarines.

• Armor (hydrology)
• Deep sea
• Littoral
• Profundal zone
• Limnetic zone
• Lake stratification
• Benthos
• Stream bed
• Water column
• Intertidal zone
• Aphotic zone
• Photic zone
• Neritic zone
• Pelagic zone

• Fathom
• Data Archive for Seabed Species and Habitats from the UK Marine Data Archive Centre