We explain what an abyssal plain in an ocean is, what living beings inhabit it and other characteristics. Plus, examples from around the world.
What is an abyssal plain?
In geology and oceanography, certain areas are known as the abyssal plain. flat expanses of land found at the bottom of seas and oceans in the underwater region known as the abyssal zone (from the Latin abyssus“abyss”). This is the deepest and darkest region of the known seas, where the least amount of sunlight penetrates and therefore life is scarce, arduous and different from the surface regions.
However, abyssal plains are different from deep oceanic depressions (such as trenches), since they are flat, submerged extensions of land, close to continental extensions. They are usually found at depths of several kilometers below the surface and extend over vast dimensions.
The geological study of these plains reveals that they have a sedimentary origin, that is, they are the result of the accumulation of sediments and substrates from nearby continents, which accumulate over thousands or millions of years until the terrain is smoothed and uniform. submarine. Some abyssal plains are composed of up to a kilometer of sediment accumulated and densified in this way.
See also: Aquatic ecosystem
Characteristics of the abyssal plains
The abyssal plains are characterized by the following:
- They are flat extensions of underwater terrain, located between 3,000 and 6,000 meters below the sea surface and in the adjacencies of the continental shelf.
- can be extremely extensive stretching hundreds of kilometers wide and thousands of kilometers long.
- They usually have irregular but elongated shape according to the margins of the continental shelf.
- consist of an abundant sedimentary layer installed on the oceanic crust, generally composed of magnesium silicates (basalt), the result of underwater volcanic eruptions, or the accumulation of materials from the continental shelf and the surface.
- They are regions of little or no luminosity given the absence of sunlight, and therefore lacking photosynthetic organisms. Life down there is very different than on the surface.
- are much more common in the Atlantic Ocean less common in the Indian Ocean and quite rare in the Pacific. In total, they represent 70% of the ocean floor.
Life on the abyssal plain
Life on the abyssal plain is found adapted to the enormous pressures resulting from the mass of water that separates it from the surface, as well as to the lack of sunlight which makes photosynthesis impossible. Furthermore, the temperatures are particularly low, so vital metabolisms tend to be slow and patients.
Much of the life in this region is microscopic made up of autotrophic bacteria that survive through chemosynthesis, taking advantage of the resources that seismic activity releases on the seabed. There are also small crustaceans, worms and simple living organisms, many of which survive thanks to the rain of organic matter (waste) that comes from the surface regions.
However, the abyssal plain is usually interrupted by hills and occasional elevations (such as oceanic ridges), and in these places life flourishes more than in its surroundings, although it does so in dark, deep and barely productive ecosystems, at least compared to those on the surface.
As to deep-sea fish are characterized by a solitary way of life adapted to extreme conditions. They have a long, slender body, with large jaws that facilitate the capture of occasional prey.
It is a rare fauna and terrifying features. Many of them are equipped with bioluminescence (that is, the ability to generate light), but not to illuminate their path, since most of them do not depend too much on sight, but rather as a way to attract their prey.
Examples of abyssal plains
Among the main known abyssal plains, the following stand out:
- The Argentine abyssal plain located in the deepest region of the Argentine basin, about 6,212 meters below sea level and just 800 km from the Malvinas Islands.
- The abyssal plain of Vizcaya located deep in the Bay of Biscay, off the Spanish coasts of Cantabria, Asturias, Galicia and the Basque Country. This plain is located about 2789 meters deep, separating the two continental shelves of the gulf.
- The abyssal plain of Somalia part of the so-called Somali basin in the Indian Ocean, east of Africa. Its relief is interrupted by several underwater mountains, which reach the surface forming the islands of the Aldabra group in the Seychelles.
- The Aleutian Abyssal Plains located in the Aleutian basin in the Bering Sea of the Pacific Ocean, about 3,900 meters below the surface. The region is characterized by deep depressions (pits) and enormous seismic activity.
- The Bellingshausen Abyssal Plain located in the Antarctic Ocean, south of the final coasts of Chile and close to Antarctica, is a plain that runs along the continental shelf of the latter, and whose name honors the Russian admiral Fabián Gottlieb von Bellingshausen, who explored the area in the 19th century.
Continue with: Ocean trenches
References
- “Abyssal plain” in Wikipedia.
- “Abyssal Plain” in Enciclopedia.us.
- “Ocean floor features” in National Oceanic and Atmospheric Administration (United States).
- “Abyssal plain (geology)” in The Encyclopaedia Britannica.
