Hadal Zone Definition| Hadal Zone animals | Hadalpelagic Zone Depth
Hadal Zone / Hadalpelagic Zone
What is Hadal Zone?
Hadal zone can be defined as the region of the oceans that is below about 6000 meters (8,500 feet) in depth. It includes the deep trenches but excludes some deep oceanic basins. The etymology of the word “hadal” is from the Greek word ἅδας, meaning “the deepest ocean.”
The deep oceanic basins that are not trenches are variously referred to as the “hadopelagic,” “eathyalic,” or “hadalpelagic” zone and have different definitions. The hadopelagic zone is defined as the deepest oceanic trench that is more than 11,000 meters (36,000 feet) deep and any oceanic basin that meets these criteria, even though they may be shallower.
The eathyalic zone is defined as the deepest oceanic trench and any oceanic basin that is between 6,000 and 11,000 meters (20,000-36,000 feet) deep. The hadalpelagic zone is defined as everything else.
The hadalpelagic zone includes all three of these zones and sometimes includes oceanic basins that are shallower than 6,000 meters as well. Oceanographers still do not agree on a definition for the hadalpelagic zone.
Of all the ocean’s depths, the deepest is located in the western Pacific Ocean. This depth was first reached by a manned vehicle during the bathyscaphe “Trieste” expedition of 1960. The Mariana Trench at 11,034 m (36,201 ft) is the deepest point of the ocean. The hadal zone accounts for 16% of the ocean’s surface area.
As of 2008, there is no direct evidence of any organism living below 10,898 m (35,870 ft).
The bottom layer of water in this region will lack many plants because it lacks light for photosynthesis to occur.
Hadal Zone Pressure
The hadal zone includes trenches that range in depth from about 6,000 to 11,000 meters (20,000-36,000 feet). Trenches are characterized by high pressure and low temperature. The pressure at the bottom of Challenger Deep in the Mariana Trench is over 1000 times higher than atmospheric pressure on Earth. At such high pressures, water is expected to be solid.
This is a region of intense pressure and cold temperatures, which makes it difficult for animal life to exist. However, some animal life does exist in this area, such as fish, “sperm whales,” and crabs. These hadal zones animals have adapted to the extreme conditions.
Hadal Zone Animals
What are the Hadalpelagic zone animals?
Hadal zone animals are those that live at extreme ocean depths, between 6,000 and 11,000 m (20,000 and 36,000 ft). It is home to many organisms found nowhere else on earth, and most hadal animals are gigantobenthic scavengers adapted to extreme pressure and lack of light.
In the deep-sea trench, on the edge of the abyssal plain, there is a small amount of life in comparison to other zones. This is because they have to compete with scavengers and as well as with predators.
The number and biomass of marine life reduce with depth. Still, the hadal zone includes a diverse variety of metazoan species, mainly benthos, such as fish, sea cucumber, bristle worms, bivalves, isopods, sea anemones, amphipods, copepods, decapod crustaceans, and gastropods. The core of these trench organisms is believed to have originated in the abyssal plains.
These creatures are adapted to pressure as deep as 8,200 meters. While we know about many of these animals, like the hadal snailfish and the hadal amphipod, many discoveries are still made. Scientists have recently discovered a new snailfish species that was caught at over 10,000 meters in the Indian Ocean.
While these species have developed adaptations to high pressure and low temperatures, such as slower metabolism, intracellular protein-stabilizing osmolytes, and unsaturated fatty acids in cell membrane phospholipids, there is no clear relationship between pressure and metabolic rate.
Increased pressure, on the other hand, can constrain organisms’ ontogenic or larval stages.
The deep-sea hydrothermal vent systems are submarine volcanoes that produce extreme heat and mineral-rich fluids. They are a unique ecosystem, producing new life forms by the magma’s geothermic activity and creating new habitats for organisms. The organisms living within these ecosystems have changed due to the changes in the habitat over time.
This zone consists of layers of sediments that have been gradually deposited for hundreds of millions of years. The sediments are made up of particles eroded from land.
Hadal Zone Temperature
Hadal zone temperature is the coldest possible temperature. The hadal zone is found in the ocean’s deepest parts, usually beyond 8,200 meters (27,000 feet). The hadal zone has not been explored because it is so deep.
The deepest part of this zone is called “hadopelagic” and extends to approximately 10,915 meters (35,800 feet) below sea level. This is the point that Sir John Murray calculated as the lowest possible temperature for any water on earth.
The temperature in the hadal zone fluctuates very little because it is so far down in the ocean. Temperature can only be found in the abyssopelagic and hadopelagic zones. The hadal zone does not affect the world’s climate because it is so deep and because it is so far down in the ocean that its close proximity to the sun also hinders heating.
The hadal zone remains largely unexplored due to its extreme depths and pressure (as much as one thousand times that at sea level). Scientists have proved that this zone is very cold with temperatures reaching minus 77 degrees Celsius (minus 160.6 degrees Fahrenheit) for a short period of time.
Hadalpelagic Zone Salinity
Hadal zone salinity is not universally accepted and has been reported as zero by some authors.
The averaged values of salinity hadal zone (Hadalpelagic zone) of below 6000 m depth is between 4.687 and 34.698 for AN1.
Average salinity varies considerably and rapidly with location, ranging from less than 0.5% in the oceans’ interiors to more than 40% in hypersaline lakes such as the Dead Sea.
Hadalpelagic Zone Depth
The Hadal Zone is an extreme environment that reaches depths of over 11,000 meters and is termed the hadal zone. This environment is so deep that any light sources cannot penetrate or reach the ocean floor. Therefore, any life forms living in this region lack any ecosystem interaction with the sunlight.