We explain what ocean trenches are, what beings inhabit them and how they are formed. Also, the deepest ocean trenches.
What is an ocean trench?
In geology and oceanography, it is known as oceanic trench or marine trench to the long and narrow depressions of the seafloor, in the form of a trench, that are commonly formed in the adjacencies of the continental shelves or of the coasts of the volcanic islands, that is to say, in the regions in which one tectonic plate subducts under another.
The ocean trenches are the deepest recorded places in the ocean, sometimes reaching 7 to 11 kilometers below the sea surface.
In these regions, sunlight is scarce, since it cannot penetrate the body of water, and therefore life is very different from how it takes place on the surface: photosynthesis is impossible, so that autotrophic life (mostly bacterial) It occurs by taking advantage of other mechanisms for obtaining energy, such as chemosynthesis.
For its part, the vast majority of animal life is made up of crustaceans and mollusks small in size. These animals as a whole are called abyssal fauna. For its part, deep-sea fish have particularly slow metabolisms and bodies adapted to effective predation using the least possible effort: huge mouths, bioluminescent elements to attract prey, for example.
In addition, the pressures in the ocean trenches are immense, given the mass of water above, and the temperatures remain around 4 ° C, so they are not the most welcoming places on the planet.
How are ocean trenches formed?
For a long time the origin of ocean trenches was a complete mystery, and scholars were surprised to find them so close to shore, rather than in the very center of the oceans. The reason for this has to do with plate tectonics, since these types of deep depressions in the ocean floor are formed in the regions where two tectonic plates meet and form a zone of subduction.
This means that one tectonic plate (the one with the highest density) dips below the other, thus forming a depression that fills with water. These regions are very seismically active, and their volcanoes and volcanic vents release matter and energy that bacteria use for chemosynthesis.
What are the deepest ocean trenches in the world?
Ocean trenches are present in all the world’s oceans, but particularly in the Pacific, probably due to their enormous tectonic activity. The deepest trenches on the planet are the following:
- Mariana Trench or Challenger Trench. Located in the western Pacific Ocean, 200 km from the Mariana Islands, where its name comes from. Crescent-shaped, some 2,550 km long and 69 km wide, it is the deepest known trench, plunging up to 11,034 meters below the surface of the sea.
- Tonga Trench. Located northwest of New Zealand, in the South Pacific Ocean, it has a maximum depth of around 10,822 meters below the sea surface and is right next to the Kermadec Trench.
- Japan Trench. Located in the Pacific Ocean, to the east of the island of Japan, it stretches between two other important graves: that of the Kuriles, and that of Izu-Ogasawara. It reaches depths of up to 10,554 meters below the sea surface.
- Kamchatka or Kuril Trench. Also located in the northwestern Pacific Ocean, east of the Kuril Islands belonging to Russia, and the Kamchatka Peninsula. It stretches for 2,900 km and records depths of up to 10,542 meters below the surface.
- Mindanao or Philippine Trench. Located in the Pacific Ocean, east of the Philippine Islands, it has a length of approximately 1,600 km and a width of 30 km, as well as depths of 10,540 meters below the sea surface.
- Kermadec Trench. Located in the Pacific Ocean, off the Australian coast, it stretches for more than a thousand kilometers to the east of the Kermadec mountain range, from which its name comes. It reaches depths of up to 10,047 meters below the sea surface.
- Puerto Rico Trench. As its name suggests, it is located in the Atlantic Ocean, serving as the border with the Caribbean Sea. It extends for 1,500 km throughout the Lesser Antilles, and is the deepest area in the Atlantic, registering 9,200 meters below sea level.
- Bougainville Trench or from New Britain. Located east of the island of New Guinea and the Solomon Islands, in the Pacific Ocean, about 1500 km from Australia, its name pays tribute to the French sailor Louis Antoine de Bougainville (1729-1811). It reaches depths of 9140 meters below the sea surface.
- South Sandwich Trench or Meteor Trench. Located in the South Atlantic Ocean, about 100 km east of the South Sandwich Islands, it represents the region’s boundary with the Scotia Sea. It is 965 kilometers long and has a maximum recorded depth of 8,428 meters below the surface.
- Atacama or Peru-Chile Trench. Located off the coasts of Chile and Peru, in the southeastern Pacific Ocean, it marks the meeting point of the Nazca and South American tectonic plates. It has a maximum depth of 8,081 meters below the sea surface.