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,
3)benthic
4)abyssal.
Due to the sheer expanse of the oceans, there exist many ecosystems based on temperature, sunlight and nutrients of a particular region.
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........
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,
3)benthic
4)abyssal.
Due to the sheer expanse of the oceans, there exist many ecosystems based on temperature, sunlight and nutrients of a particular region.
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........
