Due to there being no light, there are no plants producing oxygen, which primarily comes from ice that had melted long ago from the polar regions. This region also contains a much higher concentration of nutrient salts, like nitrogen, phosphorus, and silica, due to the large amount of dead organic material that drifts down from the above ocean zones and decomposes.
Rather than relying on producers to form the base of the food pyramid, organisms living in the abyssal zone must feed on the dead organic detritus that falls from oceanic layers above. This leaves behind a seafloor consisting mostly of brown clay and the remaining silica from dead zooplankton and phytoplankton.
In some areas of this zone, organisms are able to sustain themselves off the products of hydrothermal vents. Some bacterial species use the vents to create and use chemical energy to produce food.
For example, many of these organisms convert hydrogen sulfide to sulfate to produce chemical energy. Organisms that live at this depth have had to evolve to overcome challenges provided by the abyssal zone.
Fish and invertebrates had to evolve to withstand the sheer cold and intense pressure found at this level. They also had to not only find ways to hunt and survive in constant darkness but to thrive in an ecosystem that has less oxygen and biomass, energy sources or prey items, than the upper zones.
To survive in a region with so few resources and low temperatures, many fish and other organisms developed a much slower metabolism and require much less oxygen than those in upper zones. Their reproduction rates are also very slow, to decrease competition and conserve energy.
Animals here typically have flexible stomachs and mouths so that when scarce food items are found they can consume as much as possible. Many organisms living in this zone have evolved to minimize internal air spaces, such as swim bladders.
This adaptation helps to protect them from the extreme pressure, which can reach around 75 MPA (11,000 psi). Large eyes would allow the detection and use of any light available, no matter how small.
This is because as sunlight shines into the ocean, the water absorbs red light, while blue light, with its short wavelength, continues moving down to the water's depths. Fishes and organisms living in the abyssal zone have developed this ability not only to produce light for vision, but also to lure in prey or a mate and conceal their silhouette.
Due to this lack of light, complex designs and bright colors are not needed. Most fish species have evolved to be transparent, red, or black so they better blend in with the darkness and don't waste energy on developing and maintaining bright or complex designs.
The abyssal zone is surprisingly made up of many types of organisms, including microorganisms, crustaceans, molluscan (bivalves, snails, and cephalopods), different classes of fishes, and a number of others that might not have even been discovered yet. Most fish species fit into that classification because the seafloor contains most of the abyssal zone’s nutrients so the most complex food web or greatest biomass would be in this region of the zone.
For benthic organisms in the abyssal zone, species would need to have evolved morphological traits that could keep them out of oxygen-depleted water above the sea floor or a way to extract oxygen from the water above, but also, allow the animal access to the seafloor and the nutrients located there. While there are a number of different fish species representing many groups and classes, like Actinopterygii or ray-finned fish, there are no known members of the class Chondrichthyes, animals such as sharks, rays, and chimeras, that make the abyssal zone their primary or constant habitat.
Whether this is due to the limited resources, energy availability, or other physiological constraints is unknown. Angler fish : Some species of this fish are considered reversal while others swim and live in the upper portions of the abyssal zone.
They lack a swim bladder, so that high pressure is not an issue. The male fuses with the much larger female and fertilizes her eggs.
Tripod fish (Bathypterois granulator): Their habitat is along the ocean floor, usually around 4,720 m below sea level. Once they sense food nearby, they use their large pectoral fins to hit the unsuspecting prey towards their mouth.
Each member of this species has both male and female reproductive organs so that if a mate cannot be found, they can self fertilize. The eel's eyes most likely evolved to detect small traces of light instead of full images.
They use the fins on top of their head, which look like flapping ears, to hover over the sea floor looking for food. They use their arms to help change directions or crawl along the seafloor.
To combat the intense pressure of the abyssal zone, this octopus species lost its ink sac during evolution. They also use their strand-like structured suction cups to help detect predators, food, and other aspects of their environment.
The depth of the dusk eel habitat can be as great as 8,370 meters below sea level. It is thought to be a semelparous species, meaning it only reproduces once and then dies after.
This is seen as a way for the organism to conserve energy and have a higher chance of having some healthy strong children. This reproductive strategy could be very useful in low energy environments such as the abyssal zone.
As with all the rest of the natural world climate change has negative effects. Due to the zone’s depth, increasing global temperatures do not affect it as quickly or drastically as the rest of the world, but the zone is still afflicted by ocean acidification.
Along with climate change and ocean acidification, pollutants, such as plastics, are also present in this zone. Plastics are especially bad for the abyssal zone due to the fact that these organisms have evolved to eat or try to eat anything that moves or appears to be detritus, resulting in most organisms consuming plastics instead of nutrients.
Both ocean acidification and pollution are decreasing the already small biomass that resides within the abyssal zone. Even though no fishery can fish for organisms anywhere near the abyssal zone, they are still causing harm.
The abyssal zone depends on dead organisms from the upper zones sinking to the seafloor, since their ecosystem lacks producers due to lack of sunlight. As fish and other animals are removed from the ocean, the frequency and amount of dead material reaching the abyssal zone decreases.
A future problem for the abyssal zone could be deep sea mining operations. This could be disastrous for this extremely fragile ecosystem since the ecological dangers from mining for deep sea minerals are many.
Mining could increase the amount of pollution in not only the abyssal zone, but in the ocean as a whole, and would physically destroy habitats and the seafloor. This industry represents a looming threat to the abyssal zone and the rest of the ocean's inhabitants.
CS1 main: bot: original URL status unknown (link) ^ a b c d e f g Nelson R (October 2013). ^ Wig more G. “The unique visual systems of deep sea fish”.
^ Praise IG, Free R, Bailey DM, Bergs tad OA, Collins MA, Dub JE, Henriques C, Jones EG, King N (June 2006). That 95 percent of the ocean remains unexplored makes sense when we realize that we know so little about the life underwater.
It was this lack of information that prompted the British naturalist, Edward Forbes to claim that the possibility of life below 540 m (less than 2,000 ft) was as good as none. It was only after we pulled off some remarkable deep sea expeditions that we realized that the dark depths of the ocean are much more fascinating than what we thought.
For instance, we realized that there existed species which could withstand the extreme pressure in the deepest part of the world’s ocean, only when Swiss oceanographer, Jacques Pic card and Lt. Don Walsh of the United States Navy explored the Challenger Deep in 1959. Over the course of time, more of such facts came to light, and researchers divided the deep sea into five pelagic layers.
Despite the extreme conditions prevailing in this zone, it has quite a few interesting and some unusual things to its credit. The Abyssal Zone, also known as the AbyssopelagicZone or simply, the Abyssderived from the Greek word, meaning bottomless the part of the ocean which is typically characterized by uniform darkness, low temperature (around 3 degrees Celsius), and unique fauna.
It roughly starts at a depth of 4,000 m (13,000 ft) and ends at 6,000 m (19,500), which is where the Heyday Zone, named after the Greek god, Hades, begins. Its nutrient salt concentration is uniform times, higher than what it is in shallow water; courtesy, the dead biological matter that settles in this zone.
Instead, tiny microbes, known as zoophytes, act as producers in this zone by resorting to the process of chemosynthesis and oxidizing hydrogen sulfide coming from vents in the ocean floor. Some examples of abyssal zone animals are giant squid (Architects due), colossal squid (Mesonychoteuthis Hamilton), black swallowed (Chiasmodon Niger), humpback angler fish (Melanocytes Johnson), deep-sea glass squid (Neutropenia pellucid), ogreish (Anoplogaster cornea), hagfish (Epictetus cirrhosis), hydrothermal vent crab (Bythograea thermydron), giant tube worm (Tennis jerichonana), etc.
As food is scarce in the Abyssal Zone, most animals resort to various physical and behavioral adaptations to survive. The humpback angler fish (Melanocytes Johnson), for instance, has a large mouth with long teeth, which helps it grab its prey the moment it is in close range.
Other physical adaptations include gray or black color, which acts as a camouflage in the deep sea environment, and bioluminescence, i.e., the ability to produce light by physiological processes, which helps the species lure their prey. Most species found in this zone are ambush predators, who wait for their prey to come to them, instead of expending energy chasing them.
This zone is characterized by the presence of hydrothermal vents, also known as black smokers that release toxic chemicals. What we need to realize, is the fact that the ocean is a single unit and anything we drop in it will simply keep moving within and affecting lifeforms that come in contact with it.