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The benthic zone is the ecological region at the lowest level of a body of water
Body of water

A body of water is any significant accumulation of water, usually covering the Earth or another planet. The term body of water most often refers to large accumulations of water, such as oceans, seas, and lakes, but it may also include smaller pools of water such as ponds, puddles or wetlands....
 such as an ocean
Ocean

An ocean is a major body of Seawater, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a World Ocean that is customarily divided into several principal oceans and smaller seas....
 or a lake
Lake

A lake is a terrain feature , a body of liquid on the surface of a world that is localized to the bottom of basin and moves slowly if it moves at all....
, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos
Benthos

Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone. They live in or near marine sedimentary environments, from tidal pools along the Intertidal zone, out to the continental shelf, and then down to the Abyssal zone....
. They generally live in close relationship with the substrate bottom; many such organisms are permanently attached to the bottom. 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.






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The benthic zone is the ecological region at the lowest level of a body of water
Body of water

A body of water is any significant accumulation of water, usually covering the Earth or another planet. The term body of water most often refers to large accumulations of water, such as oceans, seas, and lakes, but it may also include smaller pools of water such as ponds, puddles or wetlands....
 such as an ocean
Ocean

An ocean is a major body of Seawater, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a World Ocean that is customarily divided into several principal oceans and smaller seas....
 or a lake
Lake

A lake is a terrain feature , a body of liquid on the surface of a world that is localized to the bottom of basin and moves slowly if it moves at all....
, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos
Benthos

Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone. They live in or near marine sedimentary environments, from tidal pools along the Intertidal zone, out to the continental shelf, and then down to the Abyssal zone....
. They generally live in close relationship with the substrate bottom; many such organisms are permanently attached to the bottom. 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
Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.As the term is used by geologists, sand particles range in diameter from 0.0625 to 2 millimeters....
 bottoms, rock outcrops, coral
Coral

Corals are marine organisms from the class Anthozoa and exist as small sea anemone?like polyps, typically in colonies of many identical individuals....
, and bay mud
Bay mud

Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuary, which are normally in temperate regions that have experienced cyclical glacial cycles....
.

Description

The benthic region begins at the shore line (intertidal
Intertidal zone

The intertidal zone is the area that is exposed to the air at low tide and submerged at high tide, for example, the area between tide marks. This area can include many different types of habitats, including steep rocky cliffs, sandy beaches, or wetlands ....
 or eulittoral zone) and extends downward along the surface of the continental shelf
Continental shelf

The continental shelf is the extended perimeter of each continent and associated coastal plain, and was part of the continent during the glacial periods, but is undersea during Ice age such as the current epoch by relatively shallow seas and Bay....
 out to sea. The continental shelf is a gently sloping benthic region that extends away from the land mass. At the continental shelf edge, usually about 200 metres deep, the gradient greatly increases and is known as the continental slope. The continental slope drops down to the deep sea floor. The deep-sea floor is called the abyssal plain
Abyssal plain

Abyssal plains are flat or very gently sloping areas of the deep ocean basin floor. They are among the Earth's flattest and smoothest regions and the least explored....
 and is usually about 4000 metres deep. The ocean floor is not all flat but has submarine ridges
Mid-ocean ridge

A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, typically having a valley known as a rift running along its spine, formed by plate tectonics....
 and deep ocean trenches known as the hadal zone
Hadal zone

Hadal zone or or Hadopelagic zone is the delineation for the deepest trenches in the ocean. This zone is found from a depth of around to the bottom of the ocean....
.

For comparison, the pelagic zone
Pelagic zone

Any water in the sea that is not close to the bottom is in the pelagic zone. The word pelagic comes from the Greek language p??a??? or p?lagos, which means open sea....
 is the descriptive term for the ecological region above the benthos, including the water-column up to the surface. Depending on the water-body, the benthic zone may include areas which are only a few inches below water, such as a stream or shallow pond; at the other end of the spectrum, benthos of the deep ocean includes the bottom levels of the oceanic abyssal zone
Abyssal zone

The abyssal zone is the abyssopelagic layer of pelagic zone that contains the very deep benthic communities near the bottom of oceans. "Abyss" is from the Greek language word meaning "bottomless sea"....
.

For information on animals that live in the deeper areas of the oceans see aphotic zone
Aphotic zone

The aphotic zone is the portion of a lake or ocean where there is little or no sunlight.It is formally defined as the depths beyond which less than 1% of sunlight penetrates....
. Generally, these include life forms that tolerate cool temperature
Temperature

In physics, temperature is a physical property of a Physical system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature....
s and low oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
 levels, but this depends on the depth of the water.

Organisms

Benthos
Benthos

Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone. They live in or near marine sedimentary environments, from tidal pools along the Intertidal zone, out to the continental shelf, and then down to the Abyssal zone....
 are the organisms which live in the benthic zone, and are different from those elsewhere in the water column. Many are adapted to live on the substrate (bottom). In their habitats they can be considered as dominant creatures. Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column. The pressure difference can be very significant (approximately one atmosphere
Atmosphere (unit)

The standard atmosphere is an international reference pressure defined as 101,325 Pascal and formerly used as unit of pressure . For practical purposes it has been replaced by the Bar which is 100,000 Pa....
 for each 10 meters of water depth).

Because light does not penetrate very deep ocean-water, the energy source for the benthic ecosystem is often organic matter from higher up in the water column which drifts down to the depths. This dead and decaying matter
Detritus

Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
 sustains the benthic food chain
Food chain

Food chains, also called, food networks and/or trophic social networks, describe the eating relationships between species within an ecosystem....
; most organisms in the benthic zone are scavengers or detritivores. Some microorganism
Microorganism

A microorganism or microbe is an organism that is microscopic . The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design....
s use chemosynthesis
Chemosynthesis

Chemosynthesis is the biological conversion of one or more carbon molecules and nutrients into organic matter using the oxidation of inorganic molecules or methane as a source of energy, rather than sunlight, as in photosynthesis....
 to produce biomass
Biomass (ecology)

Biomass, in ecology, is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community....
.

In 2007, a deep-water frilled shark was found alive off the coast of Japan near the Awashima Marine Park in Shizuoka, southwest of Tokyo. The shark was captured but, being in poor health, died shortly afterwards.

Habitats

In ocean
Ocean

An ocean is a major body of Seawater, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a World Ocean that is customarily divided into several principal oceans and smaller seas....
ic environments, benthic habitats can be further zoned by depth. From the shallowest to the deepest are: the epipelagic (less than 200 meters), the mesopelagic
Mesopelagic

The mesopelagic is a pelagic zone extending from 200 m down to around 1000 m below sea level. It is located between the photic zone epipelagic and the aphotic zone bathypelagic, where there is no light at all....
 (200–1000 metres), the bathyal (1000–4000 meters), the abyssal (4000–6000 meters) and the deepest, the hadal (below 6000 meters).

The lower zones are in deep, pressured areas of the ocean. Because of the high pressures and seclusion neither tidal changes nor human impacts have had much of an effect on these areas, and the habitats have not changed much over the years. Many benthic organisms have retained their historic evolutionary characteristics; some organisms have significantly changed size.

It is not easy to map or observe these organisms and their habitats, and most observation has been done through remote controlled submarine
Submarine

A submarine is a watercraft capable of independent operation below water. It differs from a submersible, which has only limited underwater capability....
s.

See also

  • Aphotic zone
    Aphotic zone

    The aphotic zone is the portion of a lake or ocean where there is little or no sunlight.It is formally defined as the depths beyond which less than 1% of sunlight penetrates....
  • Armor (hydrology)
    Armor (hydrology)

    Armor, in hydrology and geography is the association of surface pebbles, rocks or boulders with stream beds or beaches. Most commonly hydrology armor occurs naturally; however, a man-made form is usually called riprap, when shorelines or stream banks are fortified for erosion protection with large boulders or sizable manufactured concrete ob...
  • Deep sea
    Deep sea

    File:Nur04506.jpgThe deep sea, or deep layer, is the lowest layer in the ocean, existing below the thermocline, at a depth of 1000 fathoms or more....
  • Intertidal zone
    Intertidal zone

    The intertidal zone is the area that is exposed to the air at low tide and submerged at high tide, for example, the area between tide marks. This area can include many different types of habitats, including steep rocky cliffs, sandy beaches, or wetlands ....
  • Lake stratification
    Lake stratification

    Lake stratification is the separation of lakes into three layers:# Epilimnion - top of the lake.# Metalimnion - middle layer that may change depth throughout the day....
  • Littoral
    Littoral

    In coastal environments and biomes, the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged....
  • Neritic zone
    Neritic zone

    The neritic zone, also called the Littoral zone#Sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters ....
  • Pelagic zone
    Pelagic zone

    Any water in the sea that is not close to the bottom is in the pelagic zone. The word pelagic comes from the Greek language p??a??? or p?lagos, which means open sea....
  • Photic zone
    Photic zone

    The photic zone or euphotic zone is the depth of the water in a lake or ocean, that is exposed to sufficient sunlight for photosynthesis to occur....
  • Profundal zone
    Profundal zone

    The profundal zone is a deep zone of a body of water, such as an ocean or a lake, located below the range of effective light penetration. This is typically below the thermocline, the vertical zone in the water through which temperature drops rapidly....
  • Tide pool
    Tide pool

    Tide pools are rocky pools by oceans that are filled with seawater. Tide pools are habitats of uniquely adaptable animals that have engaged the special attention of naturalists and marine biology, as well as philosophical essayists: John Steinbeck wrote in The Log from the Sea of Cortez, "It is advisable to look from the tide pool to the...
  • Sediment Profile Imagery
    Sediment Profile Imagery

    Sediment Profile Imagery is an underwater technique for photographing the interface between the seabed and the overlying water. The technique is used to measure or estimate biological, chemical, and physical processes occurring in the first few centimetres of sediment, Groundwater, and the important benthic boundary layer of water....
     (SPI)
  • Stream bed
    Stream bed

    A stream bed is the channel bottom of a stream, river or creek; the physical confine of the normal water flow. The lateral confines or channel margins, during all but flood stage, are known as the stream banks or river banks....
  • Water column