Abyssal Zone Animals: Life in the Deep Sea

The vast oceans of the Earth are deep, reaching depths of around 4,000 metres (13,123 feet) in most places. Trenches, on the other hand, can form underwater canyons that extend for another 7,000 metres (22,965 feet). The abyssal zone is defined as the seafloor and water column between 3,000 and 6,500 metres (9,842 and 21,325 feet) in depth. It is also known as the abyss. Because sunlight does not penetrate these depths, the waters are extremely dark. Temperatures here are frigid and pressures are hundreds of times greater than those at the ocean’s surface. The abyssal zone is a strange, harsh world that seems ill-adapted to support life. However, life has still found a way to thrive here. The abyssal zone animals have special features. Many abyssal animals can produce their own light, as the deep sea is completely dark.

Abyssal Zone: Depth

The abyssal zone is the bottom most layer of the ocean. The name comes from a Greek word “Abyss” meaning “no bottom” because they thought the ocean was bottomless. At depths of 3,000 to 6,000 meters (which is approximately 9,800 to 19,700 ft), this zone remains in acute darkness.

The abyssal realm is the largest environment in the Earth’s life. This zone covers approx 300,000,000 square km (that is 115,000,000 square miles). The zone covers almost 60 percent of the global surface and about 83 percent of the area of the oceans and seas.

At the air-sea interface, the waters of the Abyssal zone originate. The air-sea interface is in the polar regions, specifically in the Antarctic zone. For the cold climate of the Antarctic, it produces sea-ice and residual cold brine. Further for the high density in this region, the brine sinks and it slowly flows along the bottom towards the Equatorial region. Abyssal salinities range between 34.6 and 35.0 parts per thousand. However, the temperature ranges mostly between 0° and 4° C (that is approximately 32° and 39° F).

The Pressure system increases by about one atmosphere with each 10-meter increment in the level of depth. Which is approximately 14.7 pounds per square inch at sea level. Thereby, the abyssal pressures range between 200 and 600 atmospheres. The pressure in this realm presents fewer problems for the animals. This is because the pressures within their bodies are the same as those which are outside them.

Abyssal Zone Animals Definition

 Abyssal Zone Animals mean the living creatures including creatures and plants in the biogeographic realm consisting of the deep sea, lacking higher plant life because of the absence of light. The realm is occupied chiefly by carnivorous species that are often blind or have special luminous organs and have structure adapted to resist the great pressures of this level. The life that is found in the Abyssal Zone includes chemosynthetic bacteria, tubeworms, and small fish that are dark in colour or transparent. It also includes sharks and invertebrates such as squid, shrimp, sea spiders, sea stars, and other crustaceans

Abyssal Zone Animals Live

Because it is separated from the storms that agitate the ocean at the air-sea interface, the abyssal zone is very calm. Low energy levels are reflected in the character of abyssal sediments. The abyssal realm is usually far enough away from land. As a result, the sediment contains mostly microscopic plankton remains from the food chain in the overlying waters.

Characteristics

The animals of the abyssal plain belong to the same groups as the animals of the continental shelf; you can find octopus, squid, fish, worms and mollusks there. But the animals of the abyssal plain tend to have special adaptations to help them cope with their unusual environment. Most animals in the abyssal plain tend to be small, for example, but they usually have large, flexible stomachs and big mouths. Since food is hard to find, they need to swallow as much as they can when they find it — and preferably store some of it, because their next meal could be a long time coming. The viperfish, for example, can rotate its skull upwards so it can eat large fish. It also has an oversized stomach to store plenty of food, and a ferocious-looking set of fangs to chomp down on its prey.

Special Features

Many abyssal animals are bioluminescent, meaning they can produce their own light. This capability is important because the deep sea is completely dark. The ability to produce light can help fish lure their prey, find prey or attract mates. Often they have special adaptations to help them reproduce, because finding mates in the dark and sparsely-populated world of the abyssal plain can be difficult. Male anglerfish, for example, literally attach themselves physically to the female. They use her blood for food, like a parasite, and fertilise her eggs in return.

Species Found

Because the ocean’s depths have yet to be explored, it is unknown how many species live in the abyssal zone. When scientists collect abyssal specimens for research, they frequently discover species that are entirely new to science. In comparison to continental shelves, the deep sea is also very sparsely populated, owing to the scarcity of food. Because of the frigid temperatures of the ocean water, the animals that live here have very slow metabolic rates and only eat on occasion. Sometimes only once every few months. Because of their slow metabolism, long, pinkish-colored hagfish, for example, can go up to seven months without eating.

Food

Photosynthesis in the ocean takes place in the sunlit upper layers. When organisms living in these upper layers die, their remains slowly drift down toward the ocean floor. The animals of the abyssal zone rely on this detritus for their food. Some of them rely on it directly. However, others eat organisms that eat detritus. The one exception to this is found around rifts where tectonic plates are spreading apart and new seafloor is being formed. In these areas, some species of bacteria can use chemical energy to make their own food, and in turn, become food for other abyssal animals like tube worms. Many of these bacteria convert hydrogen sulphide to sulphate and store the energy extracted from this reaction.

Abyssal Zone Animals Types

Surprisingly, the abyssal zone is home to a wide range of organisms. Microorganisms, crustaceans, mollusks (bivalves, snails, and cephalopods), and some fish classes are among these organisms. However, there may be some undiscovered animals.

The abyssal fauna is extremely limited in number of species. This includes representatives from all major marine invertebrate phyla as well as several fish species. All of the organisms have adapted to a climate with no diurnal or seasonal changes, high pressures, darkness, calm water, and soft sediment bottoms. These animals are usually grey or black, with delicate structure and no streamline.

Animals attached to the bottom have stalks, while mobile forms have long legs. They can rise above the water layer closest to the bottom, where oxygen is scarce. Carnivores and scavengers become less abundant as depth increases, while animals that feed on mud and suspended matter become more abundant. Abyssal animals have a slow reproduction rate.

Crustaceans and Abyssal Molluscs

Colossendeis: This genus of marine spiders, some of which are bioluminescent, lives in deep water. It is notable for the length of their limbs. They are among the largest sea spiders, with leg spans of about 40–50 centimeters.

Vampire Squid: The vampire squid is among the animals of the abyssal zone. It is found throughout temperate and tropical oceans in extreme deep-sea conditions. The vampire squid uses its bioluminescent organs and its unique oxygen metabolism to thrive in the parts of the ocean with the lowest concentrations of oxygen. It releases a sticky cloud of bioluminescent mucus to scare off predators.

Telescope Octopus: The telescope octopus is a species of pelagic octopus found in tropical and subtropical regions of the Indian and Pacific Oceans. It is transparent, almost colorless, and has 8 arms. One can distinguish it from other octopus’ species by its translucent, tubular eyes.

Abyssal Zone Animal List

Angler fish

This fish inhabits the depths of all the oceans on our planet. It is a species of great size, being able to reach more than a meter in length. These strange looking fish have a stout body, a large head, and an enormous mouth. But their most distinctive feature is a whip-like rod that protrudes out of their head. It ends in a blob called a ‘lure’. This lure glows with light in the dark ocean depths and helps to attract prey.

Nether Anglerfish

Nether Anglerfish is also a denizen of abyssal zone. This species has a very unique reproduction process and has an extreme case of sexual dimorphism.

The female can grow to be a meter long, but the male is a parasite ten times smaller. The male fish lacks even a digestive system. It does, however, attach itself to the female’s body. He feeds on her nutrients and produces sperm there. Males have a highly developed sense of smell and can detect pheromones from females.

Pelican Eel

This species is found in the abyssal zone. It is present in temperate areas of all oceans. It measures about 60 cm and its shape is similar to an eel. Therefore, also named as “voracious eel”. When it encounters prey, this fish blows up its mouth to impressive dimensions. Therefore, creating a massive net that can scoop up a squid or a swarm of shrimp.

Abyssal Zone Animals

Despite the fearsome size of its mouth, however, the pelican eel isn’t a particularly athletic hunter. The fish has extremely small eyes and therefore can’t rely on sight to locate prey. Instead, the pelican eel uses a pink (or occasionally red) light on its rear fins to lure its prey.

Tube Worms

Tube worms are a species which adapt to the abyssal zone. These giant tube worms grow up to eight feet (over two meters) in length and have no mouth and no digestive tract. They depend on the bacteria living inside them for their food. The bacteria actually convert the chemicals from the hydrothermal vents into organic molecules that provide food for the worm.

Abyssal Zone Animals

 The feature of these worms is their bright red plume. This is a special organ that exchanges compounds like oxygen, carbon dioxide, and hydrogen sulphide with seawater. This plume provides nutrients to the bacteria that live inside the worm. The worm’s outer tube is made of chitin, a tough, natural substance. Chitin is also a major component of the outer shell of crabs, lobsters, and shrimp. Despite the fact that the worms lack eyes, they can detect movement and vibrations and will retreat into their protective tubes when threatened.

Deep Sea Jellyfish

Deep-sea jellyfish are among the animals of the abyssal zone. live in very deep waters, as far as 23,000 feet below the ocean’s surface. Most jellies range from less than half an inch (1 cm) wide to about 16 inches (40 cm), though the smallest are just one millimeter wide. The largest ones are about more than 10 meters (33 feet) in length.

They are the colourful residents of the deep sea as they produce their own light. The giant phantom jellyfish is the biggest deep sea jellyfish. It was captured as it was serenely floating, its long, velvety “mouth-arms” trailing around it at a depth of 3,200 feet.  Most jellies primarily eat plankton, tiny organisms that drift along in the water, although larger ones may also eat crustaceans, fish and even other jellyfish and comb jellies.

Abyssal Zone Animal Facts

In order to survive the harshness of the abyssal zone, animals have grown adaptations to their environment. Examples of these adaptations are —

  • The animals here are blind or semi blind due to the lack of light.
  • Many abyssal animals are bioluminescent, which means they can produce their own light. Because the deep sea is completely black, the ability to produce light can help fish in some activities. These include luring prey, finding prey, and attracting mates etc.
  • Finding mates in the dark and little-populated world of the abyssal zone can be difficult. Therefore, the fishes adapt to some strategies. Anglerfish, for example, physically attach themselves to a female, using her blood as food and fertilizing her eggs in return.
  • The water in the ocean is extremely cold. As a result, the animals here have extremely slow metabolic rates and only eat on occasion. They may only eat once every few months. Because of their slow metabolism, hagfish, for example, can go up to seven months without eating.

F.A.Qs

1. What is the abyssal zone in the ocean?

 Ans. The abyssal zone extends from 13,100 feet (4,000 meters) to 19,700 feet (6,000 meters). It is the pitch-black bottom layer of the ocean. The name comes from a Greek word meaning “no bottom” because they thought the ocean was bottomless.

2. What animals live in the abyssal zone?

Ans. The life that is found in the Abyssal Zone includes chemosynthetic bacteria, tubeworms, and small fish that are dark in colour or transparent. It also includes sharks and invertebrates such as squid, shrimp, sea spiders, sea stars, and other crustaceans

3. What animal is adapted to the abyssal zone of the ocean?

Animals in this zone include anglerfish, deep sea jellyfish, deep sea shrimp, cookiecutter shark, tripod fish, and abyssal octopus also known as the dumbo octopus.

4. How do animals in the abyssal zone survive?

Ans. Special Features. Many abyssal animals are bioluminescent, meaning they can produce their own light. This capability is important because the deep sea is completely dark, and the ability to produce light can help fish lure their prey, find prey or attract mates.

5. What do animals in the abyssal zone eat?

Ans. Animals living on the abyssal plains, miles below the ocean surface, don’t usually get much to eat. Their main source of food is ”marine snow”. It is a slow drift of mucus, fecal pellets, and body parts that sinks down from the surface waters.

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