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Benthos is ... Plankton, nekton, benthos

Plankton, nekton, benthos are three groups into which all aquatic living creatures can be divided. Plankton form algae and small animals that float near the surface of the water. Necton consists of animals that can actively swim and dive in the water, such as fish, turtles, whales, sharks and others. Benthos are organisms that live in the lowest layers of the aquatic environment. It includes animals that are environmentally related to the bottom, including many echinoderms, benthic fish, crustaceans, mollusks, annelids and so on.

Types of marine life

Marine animals are divided into three groups: plankton, nekton, benthos. Zooplankton is represented by drifting animals, which are usually small in size, but can grow to fairly large sizes (eg, jellyfish). Zooplankton can also include temporary larval forms of organisms that can grow and leave plankton communities and join such groups as nekton, benthos.

The class of nekton is the largest part of the animals living in the ocean. A variety of fish, octopus, whales, moray eels, dolphins and squid are all examples of nekton. This large-scale category includes a variety of very diverse creatures that are very different from one another in many ways.

What is benthos? The third type of marine animals that spend their whole life on the ocean floor. This group includes lobsters, sea stars, all kinds of worms, snails, oysters and many others. Some of these creatures, such as lobsters and snails, can move independently on the bottom, however their lifestyle is so strongly connected with the ocean floor that they could not survive away from this environment. Benthos are organisms living on the ocean floor and include plants, animals and bacteria.

Plankton - the most common form of life in the aquatic environment

When you imagine life in the ocean, then usually all associations are somehow connected with fish, although in fact fish is not the most common form of life in the ocean. The largest group is plankton. The other two groups are nekton (actively swimming animals) and benthos (these are living organisms inhabiting the bottom).

Most species of plankton are too small to see with the naked eye.

There are two main types of plankton

  • Phytoplankton, which produces food by photosynthesis. Most of them are different algae.
  • Zooplankton, which feeds on phytoplankton. It includes tiny animals and fish larvae.

Plankton: general information

Plankton are microscopic inhabitants of the pelagic environment. They are the most important components of food chains in the aquatic environment, since they provide nectonic nutrition (crustaceans, fish and squid) and benthos (sea sponges). They also have a global impact on the biosphere, since the balance of the components of the Earth's atmosphere largely depends on their photosynthetic activity.

The term "plankton" originated from the Greek planktos, which means "wandering", or "drifting". Most of the plankton maintains its existence, swimming along with ocean currents. However, not all species swim with the flow, many forms can control their movements, and their survival is almost completely dependent on their independence.

Dimensions and representatives of plankton

In size, plankton varies from tiny microbes, the length of which is 1 micrometer, to jellyfish, whose gelatinous bell can reach 2 meters in width, and the tentacles can extend more than 15 meters. However, most plankton organisms are animals less than 1 millimeter in length. They exist due to nutrients in sea water and through photosynthesis.

Representatives of plankton are the most diverse organisms, such as algae, bacteria, protozoa, larvae of some animals and crustaceans. Most plankton protists are eukaryotes, mostly single-celled organisms. Plankton can be divided into phytoplankton, zooplankton and microbes (bacteria). Phytoplankton performs photosynthesis, and zooplankton is represented by heterotrophic consumers.

Nekton

Representatives of nekton are active swimmers and often the most famous organisms in sea waters. These are the main predators in most marine food chains. The difference between nekton and plankton is not always sharp. Many large animals (for example, tuna) spend their larval stage in the form of plankton, while in the adult stage it is quite large and active nekton.

The overwhelming majority of nekton are vertebrates, these are fish, reptiles, mammals, mollusks and crustaceans. The largest group consists of fish, there are approximately 16,000 species. Necton is found at all depths and latitudes of the sea. Whales, penguins, seals are typical representatives of the nekton in the polar waters. The greatest variety of nekton can be found in tropical waters.

The most diverse form of life and its economic value

It also includes the largest mammal on planet Earth, the blue whale, which grows to 25-30 meters in length. These giants, as well as other baleen whales, feed on plankton and micronucleon. The largest representatives of the nekton are whale sharks, which reach a length of 17 meters, as well as toothed whales (whales), large white sharks, tiger sharks, blue tuna and others.

Necton is the basis of fishing around the world. Anchovies, herring, sardines usually range from one-quarter to one-third of the annual sea yield. Economically valuable nekton are also squid. Halibut and cod are benthic fish, which are of commercial importance as food for humans. As a rule, they are extracted in the waters of the continental shelf.

Benthos

What is the meaning of the word "benthos"? The term "benthos" comes from the Greek noun bentos and means "the depths of the sea". This concept is used in biology to refer to a community of organisms on the sea floor, as well as freshwater bodies such as lakes, rivers and streams.

Benthic organisms can be classified according to size. Macrobenthos include organisms that are more than 1 millimeter in size. These are various gastropods, bivalve mollusks, sea lilies, carnivorous starfish and gastropod mollusks. Organisms with sizes from 0,1 to 1 mm are large microbes, dominating in bottom food chains, performing the role of biogenic waste heat, primary producer and predator. The category of microbenthos includes organisms smaller than 1 millimeter, diatoms, bacteria and infusoria. Not all benthic organisms live in sedimentary rocks, some communities live on rocky substrata.


There are three different types of benthos

  1. Infauny - organisms that live on the ocean floor, buried in the sand or hiding in seashells. They have very limited mobility, live in sediment, are exposed to the environment and have a fairly long lifespan. These include sea shells and various shellfish.
  2. Epiphanes can live and move along the surface of the seabed to which they are attached. They live by attaching to rocks or moving over the surface of sediments. These are sponges, oysters, snails, starfish and crabs.
  3. Organisms that live on the ocean floor, but can also float in the water above it. This includes soft bottom fish - puffers, flounder, using crustaceans and worms as a source of food.

The relationship between the pelagic environment and benthos

Benthos are organisms that play a crucial role in the marine biological community. Benthic species are a heterogeneous group, which is the main link in the food chain. They filter water in search of food, remove sediments and organic substances, thus purifying water. At the bottom of the seas and oceans unused organic substances settle, which are then processed by benthic organisms and returned to the water column. This process of mineralization of organic matter is an important source of nutrients and is critical to ensuring high primary production.

The concepts of pelagic and benthic environments are interrelated among themselves according to many criteria. For example, pelagic plankton is an important source of food for animals that live on soft or stony ground. Anemones and sea ducks serve as a natural filter for the surrounding water. The formation of the pelagic environment at the bottom is also due to molting of crustaceans, exchange products and dead plankton. Over time, plankton forms marine deposits in the form of fossils, which are used to determine the age and origin of rocks.

Aquatic organisms are classified according to their habitat. Scientists believe that the habitat of these animals has a huge impact on their evolution. Moreover, most of them have adapted well to life in the specific environment that they inhabit. What is the main difference between the groups named plankton, benthos and nekton?

Plankton are microscopic or small animals in comparison with the other two types. Necton is a freely floating animal. What is benthos? It is referred to as freely moving, and those organisms that do not represent their existence without the ocean floor. And what about organisms that live mostly on the bottom, but can also swim - octopus, fish-saw, flounder? Such forms of life can well be called a nektobentos.

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