Suggested Oceans as a biodome


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70% of the Earth's surface is covered with water.

The vast oceans are the largest ecosystem in the world. The oceans are home to the richest and most diverse habitat on this planet. Right from the microscopic creatures to the gigantic blue whale, an ocean biome supports the highest number of life-forms.
The oceans are divided into four zones, each with different life-forms.
These are:
1) intertidal,
2) pelagic,
Due to the sheer expanse of the oceans, there exist many ecosystems based on temperature, sunlight and nutrients of a particular region.
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1) The Intertidal Zone:
The area where ocean meets the land is called the intertidal zone. As the tides lash the coastal areas, this habitat is sometimes submerged in water and exposed when the water recedes. Hence, the life-forms thriving in this system are constantly changing. In high areas or rocky sea coasts, where there is less water, few varieties of algae and mollusks are found. Regions submerged for most part of the year, have varieties of algae, snails, crabs, sea stars (star fish) and small fish in its environs. Areas exposed only during the low tides are home to many invertebrates, seaweed and fish. Marshy coasts contain crustaceans, crabs or predatory birds thronging the shores.
The Intertidal Zone is divided into six specific regions:

1) The Black Zone (or Splash Zone)
2) The Periwinkle Zone (or Splash Zone)
3) The Barnacle Zone (or Upper Zone)
4) The Rockweed Zone (or Middle Zone)
5) The Irish Moss Zone (or Lower Zone)
6) The Kelp Zone (or Subtidal Zone)

2) The Pelagic Zone or the Open Ocean: This area refers to the open seas which have a diverse climate. The warm and cold ocean currents frequently mix with each other causing variable temperatures. Dolphins and whales are included in this zone along with a variety of fish like the herring and tuna. Few varieties of sharks can also be seen swimming in this region. The plant growth is limited to certain seaweeds. Many of the fish and mammals feed on plankton, which is found in abundance in this zone.

Depending on how deep the sea is, the pelagic zone can extend up to five horizontal layers in the ocean. From the top down, these are:
A) Epipelagic (sunlit)
From the surface down to around 200 m (650 ft).
This is the illuminated zone at the surface of the sea where there is enough light for photosynthesis. Nearly all primary production in the ocean occurs here. Consequently, plants and animals are largely concentrated in this zone.
Examples of organisms living in this zone are plankton, floating seaweed, jellyfish, tuna, many sharks,and dolphins.
B)Mesopelagic (twilight)
From 200 meters down to around 1,000 meters (3,300 ft).
Although some light penetrates this second layer, it is insufficient for photosynthesis. At about 500 m the water also becomes depleted of oxygen. Still, life copes, with gills that are more efficient or by minimizing movement.
Examples of animals that live here are: swordfish, squid, wolffish and some species of cuttlefish. Many organisms that live in this zone are bioluminescent. Some creatures living in the mesopelagic zone will rise to the epipelagic zone at night in order to feed.

C) Bathypelagic (midnight)
From 1,000 m down to around 4,000 m (13,000 ft).
At this depth the ocean is pitch black, apart from occasional bioluminescent organisms, such aslanternfish. There is no living plant life.
Most animals living here survive by consuming the detritus falling from the zones above, which is known as "marine snow", or, like the marine hatchetfish, by preying on other inhabitants of this zone.
Examples of this zone's inhabitants are giant squid, smaller squids and the dumbo octopus. The giant squid is hunted here by deep-diving sperm whales.

D) Abyssopelagic (lower midnight)
From 4,000 m down to above the ocean floor.
Very few creatures are sufficiently adapted to survive in the cold temperatures, high pressures and complete darkness of this depth. Among the species found in this zone are several species of squid; echinoderms including the basket star, swimming cucumber, and the sea pig; and marine arthropods including the sea spider. Many of the species living at these depths have adapted to be transparent and eyeless as a result of the total lack of light in this zone.
E) Hadopelagic
The deep water in ocean trenches.
This zone is mostly unknown, and very few species are known to live here (in the open areas). However, many organisms live in hydrothermal vents in this and other zones. Some define the hadopelagic as waters below 6,000 m (19,685 ft), whether in a trench or not.
The bathypelagic, abyssopelagic, and hadopelagic zones are very similar in character, and somemarine biologists combine them into a single zone or consider the latter two to be the same. Theabyssal plain is covered with soft sludge composed of dead organisms from above.

Pelagic ecosystem
The pelagic ecosystem is based on the phytoplankton which occupy the start of the foodchain.
Phytoplankton manufactures their own food using a process of photosynthesis. Because they need sunlight, they inhabit the upper, sunlit epipelagic zone, which includes the coastal or neritic zone. Biodiversity diminishes markedly in the deeper zones below the epipelagic zone as dissolved oxygen diminishes, water pressure increases, temperatures become colder, food sources become scarce, and light diminishes and finally disappears.
Pelagic birds

Pelagic birds, also called oceanic birds, are birds that live on the open sea, rather than around waters adjacent to land or around inland waters. Pelagic birds feed on planktonic crustaceans,squid and foragefish.
Examples are the Atlantic puffin, macaroni penguins, sooty terns, shearwaters, and procellariiforms such as the albatross, procellariids and petrels. (The term seabird includes birds which live around the sea adjacent to land, as well as pelagic birds).
Pelagic fish

Pelagic fish are fish that live in the water column of coastal, ocean and lake waters, but not on or near the bottom of the sea or the lake. They can be contrasted with demersal fish, which live on or near the bottom, and reef fish which are associated with coral reefs.
These fish are often migratory forage fish, which feed on plankton, and the larger fish that follow and feed on the forage fish.

Examples of migratory forage fish are herring, anchovies,capelin andmenhaden.
Examples of larger pelagic fish which predate the forage fish are billfish, tuna and oceanic sharks.

Pelagic invertebrates
Some examples of pelagic invertebrates include rill, copepods, jellyfish, decapod larvae, hyperiidamphipods, rotifers and cladocera.

Pelagic reptiles
Pelagic sea snakes are the only one of the ~65 species of marine snake to spend their entire lives in the pelagic zone. They bear live young at sea and are helpless on land. They sometimes form large aggregations of thousands along slicks in surface waters. The pelagic sea snake is the world’s most widely distributed snake species........


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The Benthic Zone
The benthic zone begins at the edge of the sea at the intertidal zone, extends out along the continental shelf, and continues down the continental slope to theabyssal plain, thousands of meters below sea level. It includes the entire seabed, rising along the mid-ocean ridges where new sea floor is continually being made, and dives down into the deep ocean trenches.

The habitats of the benthic zone vary widely depending on how far below the surface the bottom lies. Just beyond the intertidal zone, the shallow water receives ample sunlight and oxygen. Continuing down along the continental slope, the environment becomes increasingly dark and cold, and the pressure increases. A remarkable variety of organisms live in these different habitats, each with specialized adaptations reflecting the conditions of their environment.

Inhabitants of the Benthic Zone
The organisms that live in the benthic zone are collectively called "benthos." They include crustaceans, mollusks, worms, fish, and any other type of organism that makes its home on or in the seabed.
The majority of benthos are scavengers or detritus feeders that eat decomposing organic matter. Much of the food supply in the benthic zone is in the form of "marine snow," small particles of decaying organic matter that slowly descend through the water column and accumulate on the ocean floor.
Benthos in the intertidal zone include sea stars, barnacles, mussels, sea anemones, sea urchins, snails, and other creatures that attach themselves to the rocky substrate or burrow in the sand. Benthos in deeper zones include fish, crustaceans and tube worms.
Benthic Fish
Benthic fish, also known as groundfish, are those that stay on or very near the sea bottom, whether in shallow or deep water. Unlike fish that spend their time swimming, benthic fish are very dense and have negative buoyancy, allowing them to effortlessly lie on the bottom or bury themselves. Other adaptations commonly seen in benthic fish include the lack of a swim bladder and a flattened body shape. They are predominantly bottom feeders that eat detritus, or ambush predators that lie in wait for their prey to come within striking distance.
There are many different types of benthic fish. Flatfish, including flounder, halibut, plaice, sole and turbot, lie on the the sea floor or bury themselves in the sand. Asymmetrical physical adaptations include having both eyes on one side of their head, and different pigmentation on each side of their bodies; the side facing down is usually pale, while the side facing up is camouflaged. Some species of flatfish are predators, feeding on smaller fish, while others eat mainly invertebrates.
Rays and skates are also flat, but are bilaterally symmetrical, with their eyes on top of their head. These cartilaginous fish are predators that bury themselves and wait for prey, feeding largely on crustaceans, clams, oysters and snails.
Rattails are benthic fish that have a large head and mouth, and a body that rapidly tapers down to a long, narrow tail. They live in the deep sea, and are scavengers, feeding chiefly on invertebrates. Some species of rattails are brotulas, chimaeras and grenadiers.

The Abyssal Zone: This is the deepest part of the ocean. There are lesser nutrients in deep waters because of the extremely cold weather, high pressure and low oxygen content. Less amount of invertebrates and fish are found in this region. Some form of bacteria survive on minerals or hydrogen sulfide emitted due to the hydrothermal vents found deep below. The presence of these organisms initiates the food web, of which, these fish and invertebrates form an integral part.

The Abyssal zone (from the 4o C isotherm at 2000 to 3000 meters in depth down to about 6000 meters) is a term in oceanography which originally (before the mid-1800s) meant the entire depth area beyond the reach of fisherman, but later investigations led to its use being restricted to the deepest sea regions that exhibit a uniform fauna and low temperatures.

Abyssopelagic zone, is distinguished from the overlying Bathypelagic zone (or archibenthalzone) with more varied fauna and higher temperatures.

Eventually an underlying Hadal zone was defined for areas in trenches and deeps below 6000to 7000meters (m) depth.

The Abyssal zone is characterized by continuously cold waters of approximately two to three °C throughout the preponderance of its extent.
Zone Boundaries

The upper boundary of the abyssal zone ranges between 2000 to 3000 m, with the position of the 4o C isotherm generally considered the demarcation line. It is the world’s largest ecological unit, with depths exceeding 2000 m comprising over three-quarters of the world ocean.


For tropical and temperate seas the characteristic thermocline presents a vertical profile in which temperature decreases with depth; however, in polar seas, the coldest temperature is typically at the surface. This outcome is caused by direct cooling of the sea surface by intrinsically cold polar air, whose temperature is lower than that implied by extreme latitude, due to the albedo effect of sunlight reflection from snow and ice features. The sea surface cold is further amplified by cooling from sea ice and from evaporative cooling by the extremely cold polar winds, which are abated by few landform topographic features.


The Abyssal zone is generally noted for its lack of nutrients, high oxygen content, and almost total lack of sunlight. In spite of these cold dark conditions, there are a remarkable array of fish, invertebrates, bacteria and other biota that inhabit this zone; examples of the fauna here are sea urchins and sea cucumbers who roam the abyssal plain, which itself is often studded with sea lilies and other deep sea flora. The fauna tend to be translucent, red coloured, or even luminescent carnivores, with much of the food supply falling from the Mesopelagic zone and Bathypelagic zones above. Examples of these curious fauna are luminescent shrimps. Some of the permanent denizens of this deep ocean zone who are able to withstand the extremely high pressures of the Abyssal zone ar Black swallower, Tripod fish, Deep-sea anglerfish and Giant squid. Some larger abyssal fauna have underslung jaws adapted for sifting the benthic sand and mud in order to scavenge for prey.

Deep Ocean Vents
The abyssal zone supports a surprising abundance of lifeforms in the vicinity of deep-ocean vents. The vent efflux is typically at an elevated temperature and/or high concentrations of hydrogen sulfide or other chemicals.
Some of the most striking ecological features are deep hydrothermal vents, often called blacksmokers. These sea floor hot water vents features emit massive amounts of hydrogen sulfide and other minerals that form a significant base of the Abyssal food chain; in fact, an incredible diversity of bacteria and otherextremophiles feed from these nutrient rich vents. In the case of many bacterial species, metabolism of hydrogen sulfide actually is carried out. These bacteria in turn support significant size tube worms, crustaceans and many other types of higher organisms.

Deep ocean trenches and fissures that extend thousands of meters below the ocean floor are virtually unexplored. Only the Bathyscaphe Trieste, the unmanned submarine Kaiko and the Nereus submersible vehicle have been able to attain these depths. The world's marine scientists need a major governmental challenge to penetrate this mysterious realm of the Earth, most of whose secrets remain to be unlocked.

Coral Reefs and Estuaries: Besides these habitats, there are coral reefs near the US coast. The Great Barrier Reef near Australia contain corals, algae, sea urchins, octopuses and certain fish. The estuaries support marsh grasses, mangrove trees in tropical regions and a variety of macro flora. Worms, oysters and freshwater aquatic birds are also found here.
(these two post are from info from the internet and NOT my work)


Project Lead and Community Wizard
Hi metouto ! Good to see you still around :)

Nice ocean info. I would definitely like to see us breathe more life into the ocean parts of the world, and with earlier discussions about treating liquids in a way that'll support underwater plants I imagine we'll be able to :D