The aquatic bodies of the planet earth are home to so many fishes among them the deep sea fish or the deep ocean fish which are of the class Osteichthyes and they are the most intriguing and researched aquatic creatures. They survive in deep waters and dark surroundings under all the pressure from the water above. The deep sea fish thrive in areas under the ocean where even sunlight fails to reach due to its depth, which is bound to make marine biologists curious about this species. The depth when 200 metres and below the pressure increases and the fishes surviving in such depths of darkness are called deep sea fish. They even live up to under 8370 metres. The fishes that live under the deep ends have special features for different conditions than the sea level.
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Lifecycle of the Deep Sea Fish
The eggs or larvae of the fish have oil in the plasma as they stay in a buoyancy environment in the pelagic zone at this stage.
Many of them are born in the shallow waters and as they mature they sink into the depths of the sea.
Upon maturation, they no longer float in the buoyancy state and the weight increase makes it denser than the seawater and helps them develop hydrofoils in order to provide hydrodynamic lift, unlike other fishes which at this stage develop swimmer’s bladders.
The fish also tends to develop spines as a defence mechanism except for the mesopelagic fish that usually lack defensive spines. The mesopelagic fish and use colour to camouflage themselves from other fish.
Features of the Deep Sea Fish
There are many deep sea fish representative species that lie like the deep saltwater fish under the vastness of the sea level and each has some special features depending on their class or family.
More than a dozen families of marine fishes are mid-water species and they are distinguishable due to their enlarged eyes, enormous mouths, and the presence of luminous organs.
The luminous organs can be present on several parts of the body of the deep ocean fish and they are often used to prey, communicate or be safe from predators and even for mating.
The deep sea fish have the most specialized features of any species in the world that has evolved for them to adapt to extreme conditions like high pressure, the darkness of the environment and cold.
The deep sea fish do not have any air sacs in their body so that they do not compress under the extreme pressure of the sea as they lay deep.
Their luminescence organ is a unique feature that can be present anywhere in their body.
Some deep sea fish use their needle tooth and even their sharp fins to prey.
Their bodies are expandable for them to be able to consume prey that is bigger than them.
They have hinged jaws wherein the teeth extend to the front beyond their mouth due to their large size.
A component called rhodopsin present in the eyes helps them to see even in the dim light.
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Different Deep Sea Fish Representative Species
The deep sea fish can be located in various zones of the sea and for each zone, the pressure keeps rising and the oxygen levels along with the temperatures keep on declining and they adapt their bodies to such environments.
Benthic organisms are the ones that live on the surface sea level the ones below its pelagic and epipelagic zone and of them, the marine species that inhabit the pelagic zone are only 2 per cent.
Even the organisms that inhabit the 200-1000 metres deep mesopelagic zone start to exhibit luminescence producing ability that is a characteristic feature of the deep ocean fish. In this zone, light is still measurable and below this in the depths are darker.
The bathypelagic zone that is 1000 to 4000 metres deep is the first zone inhabited by deep-sea organisms.
The abyssopelagic zone of 4000 to 6000 metres deep is the home of the deep sea fishes.
The zones where there is not a single trace of penetrated light called the aphotic zone are the bathypelagic and abyssopelagic zones where 75 percent of the ocean life inhabit.
Let us look at some of the deep sea fish at different depths of the ocean and their special characteristics:
Characteristics of Deep Sea Fish at Different Depths
Deep Sea Fish Facts
They have a very unique appearing transparent skin.
The deep sea fish have black bodies and even silvery bodies.
They have uniquely large eyes that they have adapted through an evolutionary process from ages to be able to work through in the dim deep sea.
Some of the deep sea fish that consumes prey larger than their size consumes by grasping with the help of their tentacles that have suction cups attached to them.
Many deep sea fish are monstrous-looking creatures and ironically very small in size to which the giant squid is an exception.
Atlantic wolffish, a type of deep ocean fish produces its antifreeze in the cold temperatures to keep the blood flowing.
The viperfish can stretch its stomach to double the size of its own body and this expandable nature is also an adapted mechanism to feed and survive.
The “vampire squid”, a type of cephalopod when under attack can turn itself inside out as a defence response.
The blobfish can decompress itself when taken out of the depths.
The male flabby whalefish when it reaches adulthood loses its oesophagus and stomach by fusing its mouth and stopping to feed itself. With this mechanism, it grows a massive liver with whose support it lasts a lifetime.
The slender snipe eels are very thin and long and have their anus located in their throat region.
The deep sea fish eat the scraps that reach the bottoms or feed themselves by eating each other to survive as there are no phytoplanktons due to the absence of sunlight beyond the mesopelagic zone.