Have you ever wandered why the deep sea creatures look so weird and scary , well we are going to know about this but before that we should know the reason behind this kind of evolution and the harsh environmental conditions in which they have to survive
Deep-Sea Zones :
Like the different zones of the atmosphere, there are also several zones present in the sea or oceans. Different zones found in the depth of sea or oceans are as follows :
- Mesopelagic Zone : This zone varies from 200 to 1000m below the surface of the ocean or sea . It is the twilight zone is cold with very little sunlight and several types of bioluminescent organisms which are able to produce light are found here.
Examples: Copepods, Krill, jellyfish, siphonophores, larvaceans, cephalopods, and pteropods etc are usually abundant in this zone.
- Bathypelagic Zone : It extends from a depth of 1,000 meters to 4,000 meters below the sea surface. It is also known as the midnight zone with no sunlight.The pressure in the bathypelagic zone is extreme and at depths of 4,000 meters the pressure reaches over 5850 pounds per square inch and the temperature is only 4′ celcius.
- Abyssopelagic Zone : It is the deep sea trench zone which is 4,000 to 6,000 meters below the surface and pressure varies from 200 to 600 atmospheres .
- Hadopelagic Zone : It is the extreme deep sea zone which is 6,000 to 11,000 meters below the surface level. The pressure at this point is 16000 psi.
Deep sea Environmental conditions:
The different types of conditions found in the depth of sea or oceans are as follows :
- Physical Condition :
There is extreme Pressure which is 1,000 times greater than atmospheric pressure , also the temperature is very low it’s nearly freezing and average temperature varies from 2-4°C (36-39°F), with temperatures as low as -1.8°C (28.8°F) . It is totally dark as no sunlight penetrates below 200-400 meters . Here the movement of water is very limited which leads to a stagnant or static condition .
- Chemical Conditions :
There are very less oxygen levels , oxygen scarcity is seen in this area especially in deep-sea sediments. The 2nd factor is Salinity or amount of dissolved salt in water. Salinity increases as we move deep inside due to the density of sea water.
The environment becomes more harsh due to the release of hydrogen sulphide gas which is a very Toxic chemical emitted from hydrothermal vents. Heavy Metals like high concentrations of copper, zinc, and iron are also found.
- Biological Conditions :
Due to low primary production of food , limited availability is there and food scarcity is seen thus the organisms have adapted to unique food webs to exploit specific food sourrce . Due to slow Metabolism the Organisms have adapted to methods which help them to conserve energy. Due to limited resources and harsh conditions most of the organisms rely on symbiotic relationships.
- Hydrothermal Vents :
Due to presence of hydrothermal vents and under water volcanos the temperature some times rise up to 400°C (752°F) near Vents and Chemical-Rich Fluids containing many toxic gases , minerals and metals are also emitted from vents.
Reasons Behind the weird structure
As we are now familiar with the environmental conditions of deep sea , so it will be quite easier for us to study the weird and scary structures of the deep sea creatures and the cause behind this type of evolution. Deep-sea creatures often appear unusual or frightening due to the following reasons:
- Adaptations to Extreme Environments
Due to High pressure their Bodies are either compressed or strengthened to withstand the crushing forces and to maintain their body shape and to protect the organs. They have the ability of Bioluminescence or large eyes are present to detect the limited light. Due to cold temperatures their metabolic rate is also very slow thus they have specialised circulatory systems . Due to food scarcity they have Unique feeding strategies, such as anglerfish lures.
- Evolutionary Cause
They have devolped various Defensive features like spines, venom, or camouflage for predation as due to absence of light autotrophic mode of nutrition is impossible for them. Due to limiting environmental factors they have high Competition for finding mates or resources so they have devolped Specialized traits .
- Morphological changes
As they are deprived of sunlight so they have devolped Bioluminescent lures or spots inside them and to receive even that dim light they Enlarged eyes . To feel the vibrations and the sound waves they have very sensitive sensory organs . To protect themselves from the predators they have evolved Flexible and transparent bodies and also able to change their colours according to surrounding. To survive in that high pressure the deep sea creatures have Unique skeletal systems like hydrostatic skeletons .
Examples of Deep-Sea Creatures
- Anglerfish (Lophiidae) is adapted for the capture of prey.Ranging in color from dark gray to dark brown which helps them to hide in the environment have large heads that bear enormous, crescent-shaped mouths fang-like teeth angled inward for efficient prey-grabbing.
- Vampire Squid (Vampyroteuthis infernalis) : The inner side of its mantle is very dark, making the squid invisible in the dark lightless environment around it. The tips contain tentacles and photophores . It also have organs that produce clouds of bioluminescent which are sticky mucus that will glow for up to 10 minutes, allowing it to get away from predators I’m the mean time.
- Giant Isopod (Bathynomus gigas) : They have large sensory organs to help them navigate in the dark.
- Colossal Squid (Mesonychoteuthis hamiltoni) : They also have long feeding tentacles in addition to their foot-wide eyes, which help them to absorb as much light as possible to glimpse prey as there is very less light in deep sea.
- Blobfish (Psychrolutes marcidus ) : They have soft body which has high water and fat content helping them to withstand the high pressure as they lack air bladder.
There are many more examples of organisms have modified adaptations and structures from their real species .
Why They Seem Scary ?
Due to unfamiliarity the Deep-sea creatures are alien-like as they have a completely different environment also their Size is either very Large or have unusual body proportions giving them a wired appearance. Some Features like Sharp teeth, glowing eyes, or venomous spines also give a deadly appearance to them but the important point is as we have very Limited knowledge about their behavior and habitats also we rarely get to see a glimpse of them thus they appear us to be scary.
