What are benthos How do they move

fauna

The totality of all animals in an area is called fauna. The fauna in the oceans is very diverse and rich in species. Of the approximately 8.7 million known species, approximately 2.2 million are marine animals. The largest share of marine life is made up of Marine microbes Microorganisms in the sea. Fish make up about 12% of marine animals.


Even nowadays, new and supposedly extinct animal species (e.g. coelacanth) are found again and again, especially in the deep sea.


It is generally assumed that life originated in the oceans and that various organisms "migrated" to the land at some point. There they continued to develop and some of them returned to the sea. Many bony fish or dolphins are descended from forms that originally lived on land.
The marine life is divided into three groups: plankton, nekton and benthos. The plankton includes living beings that cannot move independently in the water and that drift around in all layers. According to this, jellyfish, some of which can grow up to 5m and larger, also count as plankton.


Plankton is divided into picoplankton, nanoplankton, mesoplankton, macroplankton, megaplankton and megaloplankton, depending on its size.


Nekton are larger creatures that have the ability to move independently in the water, i.e. to swim. They make up the vast majority of the first-order consumers in the food web. Some representatives of the nektons are counted as plankton in the larval stage.


Benthos are the creatures that live above, on or in the sea floor. They are also divided into microbenthos, meiobenthos and macrobenthos depending on their size.


Marine animals usually have a lower salinity than the surrounding water. You are hypotonic to the water. To prevent dehydration, they drink large amounts of salt water and excrete most of the salt through the gills and urine. However, there are also isotonic marine animals such as starfish.


Turtles, seals, polar bears and certain sea birds (e.g. penguins) are also counted among the marine animals, as they are predominantly near the sea and are part of the marine food web. Zooplankton are animal organisms that float freely in water. Along with phytoplankton, they are among the largest producers of organic material in the marine ecosystem. It feeds mainly on phytoplankton. Many animals of the necton or benthos are temporarily zooplankton in the larval stage. Sponges are stuck lower organisms that do not yet have proper tissue. Both size (2cm-2m) as well as shape (funnel-shaped, lump, etc.) and color (red, purple, yellow, white) can vary. With a few exceptions, they live in salt water. They ingest their food through filtration. Sponges often grow together in colonies. They are partly sexually separated and partly hermaphroditic. During sexual reproduction, the seed is curled up together with the food and merges there with the eggs.The cnidarians include jellyfish, corals and anemones, among others. They are characterized by the possession of nettle capsules, which they use either for defense or to paralyze or kill the prey. They mainly feed on zooplankton, but larger cnidarians can also catch larger prey such as fish. They usually reproduce asexually, but sexual reproduction is also possible.Among the arthropods, the crustaceans have most of the marine representatives, there are almost no marine species from the other groups. They live in both fresh and salt water. As in all arthropods, the body of the crustacean consists of segments bounded by a head and an end section. They colonize the bottom of the water, reefs and crevices. You grab your food such as woodlice or worms with your scissors, which you can also use to crack the shells of snails.The best-known representatives of echinoderms are starfish and sea urchins. They get their name from the spines that have grown out of the skeleton. Except for some deep-sea species, they live on the bottom. On the one hand, they feed through filtration, sea urchins graze on algae and nutrients from the stone with their teeth, starfish actively hunt other starfish and mussels and some other species swallow seabed and extract the organic components from them.The marine representatives of the molluscs include the cephalopods (octopuses, squids, etc.), snails and mussels. The body is shielded from the environment without internal skeletal elements and by the skin. Many snails, the majority of clams, and all cephalopods are sexually separate. Mussels and snails are mostly filter feeders, while the cephalopods are active predators that feed on animal food. In addition to fish, vertebrates also include marine mammals (whales, seals, manatees, sea otters). They feed on plankton, insect larvae, snails, mussels or other vertebrates. Coarse fish feed only on plankton, insect larvae, mussels and snails, while the predatory fish also eat other fish. The marine mammals also have both herbivores and carnivores. Manatees feed exclusively on plants such as B. algae and sea grasses. Seals and most toothed whales hunt fish and other marine animals. The baleen whales feed mainly on krill crabs, which they filter out of the water.

The food chains are a linear representation of the material and energetic relationships between organisms in an ecosystem. They are divided into trophy levels. At the bottom are the producers, then the consumers and at the end the destructors, which are missing in these examples. The real relationships, however, are much more complex than they can be represented in food chains.

Food webs represent the food relationships between organisms in an ecosystem. In contrast to food chains, the relationships here are represented in several dimensions and thus better reflect reality. There is neither a beginning nor an ending point. The order of producers, consumers and destructors is nevertheless observed. The arrows are a direct food relationship such as the polar bear eats seals. However, due to the complexity and diversity of ecosystems, food webs can also only represent the real conditions with difficulty.