The crossover between the continental shelf region and the deep sea is called the archibenthal. It stretches from the sparsely illuminated sublithoral zone to the middle of the continental slope. The archibenthal is strongly influenced by changing environmental conditions, especially the decrease in light penetration, water currents, mechanical motion leading to slope erosion, nutrient transport and sediment distribution. In the bathyal the reduced, rich organic slick turns into oxidised pelagic sediment (ooze). For the distribution of animals the border of the deep sea is less clear. Whilst the shelf fauna is partially still present at depths of up to 1,000 m, some of the characteristic deep sea species can be observed at around 100 m depth in polar regions.
Present for more than 3.2 billion years these vents are the oldest known ecosystem on the planet. And theoretically they can be considered to exist elsewhere in the universe. The most important food source for deep-sea organisms is particulate organic matter, which drifts down from the surface to the seafloor and is also known as “marine snow”. From individual cells of dead plankton to clumps of algae, to whole whale cadavers – which do not count as marine snow but are instead referred to as “large foodfalls” – there are meals of all shapes and sizes. Even zooplankton excrement contains enough nutrients for other organisms to get by on. Those species that gather near hot or cold springs pursue a different strategy.

Open Ocean Zones

They range from shallow environments to the deep sea and apparently hold the record for the deepest-dwelling fish. The deep sea is home to some of the weirdest creatures on Earth, from ghostly elder fish to carnivorous harp sponges. Sometimes, scientists discover more humble creatures that are so tiny that they go unnoticed until new technology brings them into view.

DEEPER DISCOVERY

The very deepest depth of the ocean is roughly 2,000 meters deeper than Mount Everest is tall—36,070 feet deep (10,994 m)! Each zone has a different mix of species adapted to its specific light level, pressure, temperature, and community. About three-fourths of the area covered by ocean is deep, permanently dark, and cold.

• In the past 50 years, the ocean has absorbed 93% of excess heat generated by greenhouse gas emissions (Levitus et al., 2012).
• The only exceptions to this are the hydrothermal vents, where the surrounding water is around 20 to 25 °C warm.
• The Swiss marine biologist Jacques Piccard already hypothesised that fish species can be found to great depths in the ocean.
• Because many of these “underwater islands” are located in remote surroundings, studies are continually finding previously unknown and endemic species.
• The bacteria are being nurtured with oxygen and nutrients through the bloodstream.
• Diagram on the right shows how deep the different colors of light penetrate into the ocean.

Fangtooth Fish

It extends from 19,700 feet (6,000 meters) to the very bottom of the Mariana Trench at 36,070 feet (10,994 meters). In 2018, scientists officially described a snailfish (Pseudoliparis swirei) at 27,000 feet below sea level, the deepest living fish ever found. The snailfish lacks scales, has large teeth, and does not bioluminesce, a departure from what many people envision in a deep-sea fish. A second has been observed on video, however, it has yet to be captured and formally described. Despite the remoteness of the hadalpelagic, humanity still finds a way to interfere—plastic debris has been found at the bottom of the Mariana Trench.

Deep sea

With threats like climate change and mining putting deep-sea communities at risk, documenting the residents of this environment is more urgent than ever. “The deep sea is home to an incredible diversity of organisms and a truly beautiful array of adaptations. Our discovery of not one, but three, new species of snailfishes is a reminder of how much we have yet to learn about life on Earth and of the power of curiosity and exploration,” said Gerringer.

• Animals like mussels and crabs come to feed on the special bacteria by the lake’s edge, and often there are whole communities that live along the shore.
• The deep sea is home to natural resources that have been a subject of interest since the 1970s.
• Not too far away, off the coast of central California, a different MBARI research team, using the submersible Alvin, found two other unidentified fish species, each dark in color.
• Vast datasets regarding the deep sea are rare, making it even more vital to keep these regions protected from anthropogenic influences.
• While something like the gulper eel, with its massive expandable gullet, is a rare and amazing sight and could almost be mistaken for an alien.

Researchers discover carnivorous sponges that make their own light

The scientifically relevant USPAs would be ideal objects for the extension of international environmental protection to the open ocean. Scientists assume that there are some ten million undiscovered species currently living in the dark depths of the ocean. Every expedition into the aquatic realms of the deep brings new realisations. In 1977 scientists discovered hydrothermal vents, the so-called “black smokers” at the ocean ridges. These vents release minerals, mostly black sulphur compounds, which settle into chimney-like structures. Fed through the conversion of chemical energy these vents have created ecosystems entirely independent from sunlight as a source of energy, leading to their high biodiversity.
In the years since, several expeditions have returned to the site to track its development. Decades later, the scars are still clearly recognisable, and there have been lasting changes to the biotic community. The deep sea is home to natural resources that have been a subject of interest since the 1970s. These include manganese nodules, which can be found on the ocean floor at a depth of more than 4,000 metres, especially in the Pacific.

Water Column

The deep sea fish espada is a fish tourists commonly get served by locals in Madeira, but it is actually called Aphanopus carbo and is being caught in much higher quantities by the British isles these days. Deep sea sharks are, on the one hand, valued for the oil that can be obtained from their liver, but on the other hand are also now replacing the spiny dogfish in the production of ‘Schillerlocke’. And with the ever-growing motors, larger nets, and smaller mesh sizes, the factory Deep Sea ships are fishing thousands of km away from their port of origin. Further, technological developments such as the GPS or improved ocean mapping has brought even the most remote deep sea regions within reach of the fishing nations. Dispersed buoys with km-long fishing lines holding thousands of baited hooks in search of deep sea sharks are being moved through satellite control.
The regulation of excess heat and CO2 can have irreversible short term consequences on Deep Sea organisms. Concurrently with climate change, resource exploitation (minerals, hydrocarbons, fisheries) is spreading to the Deep Sea and brings its share of disruptions in fragile environments. This vital gap in international law should, according to her, be closed as soon as possible. In Russian permafrost regions it is already being attempted to min gas hydrates with conventional methods. The USA and Japan are planning their techniques for first test extractions.