The value of crustaceans for humans: positive and negative. Features of commercial and parasitic species

What is the significance of crustaceans for humans? Positive and negative. This answer will be the only true one. After all, they serve as food for animals and humans, and some are also an object of fishing. But some crustaceans lead a parasitic way of life and are intermediate hosts for helminths. The features of vital activity, the classification and significance of these arthropods, we will consider in the article.

Type of crustaceans

Representatives of this subtype of arthropods are very diverse. This determines the value of crustaceans for humans: positive and negative.

Despite this, the common features of the structure are all of them. Crustaceans (the photo below shows a crab) have a body consisting of the cephalothorax and abdomen, to which the limbs are attached. Two pairs of antennae are located on the head. The respiratory organs are the gills, the secretions are the green glands.

Living in fresh and salt water bodies, crustaceans eat both plants and small animals.

Higher cancers

Representatives of this class are crayfish. For their habitat, they choose pure running water with a high oxygen content. In the daytime they hide in holes, under stones and logs. Here they are caught by a man. Crayfish meat has valuable nutritional properties. For this reason, the number of populations of many species has recently been sharply reduced. A broad-mouthed crayfish is even listed in the International Red Book.

At night, the crabs leave their shelters and go hunting. These organisms are absolutely omnivorous. They taste like worms, mollusks, and tadpoles. And both living and dead. Do not refuse cancers and water plants. Decorative species people often breed in aquariums. In captivity, crayfish can be fed with bread, vegetables and even meat.

To commercial higher crayfish include lobsters, crabs, lobsters and shrimp. In the best restaurants of the world, dishes from them are very in demand, although not everyone can afford it.

Amphipods and water donkeys are a valuable food for many species of river and marine animals. Moistice, living in moist soil and forest litter, loosen them, enrich them with organic substances, improve the processes of nutrition and respiration of plants.

Crawfish crayfish

They are inhabitants of fresh water bodies, the head of which is sufficiently separated from the trunk. These include small crustaceans of daphnia, which are also called water fleas. Together with other aquatic organisms, they are part of the plankton, which is located in the upper layers of the reservoir.

Man artificially receives daphnia on an industrial scale for the fodder of fish. They are often used to increase species diversity in aquariums.

With the help of daphnia test the level of toxicity of fresh water bodies. These organisms are very sensitive to the content of salt solutions. They cause a slowdown in motor activity. After the crustaceans either sink to the bottom, or freeze at the surface.

Class of mandibles

The value of crustaceans for humans, both positive and negative, is also found in members of the jaw-bone class. Daphniids and cyclops he has long used as a valuable food for breeding juvenile commercial fish. Parasitic cyprinids are also crustaceans. They feed on the blood of fish, often causing significant damage to the fishery.

Many species of cyclops are intermediate hosts for parasitic flatworms. For example, a ribbon wide of an egg turns into a larva. It is called coracidium. Such a spherical larva freely floats in water until it is swallowed by crustaceans. So they become the first intermediate hosts of parasites. The second willy-nilly are predatory fish that feed on crustaceans. In the human body, larvae get into the use of poorly fried or raw fish. There they attach to the small intestinal mucosa, and after 4 weeks they become capable of reproduction. The length of this worm can reach ten meters! But the main danger lies in the fact that when the parasite is found for a long time, anemia develops in the person. Worm isolation products inhibit the formation of vitamin B12, which is necessary for the formation of hemoglobin erythrocytes. Dangerous symptoms of the disease are general weakness, decreased efficiency, hypotension, increased heart rate, frequent headaches and dizziness. These manifestations must be paid attention and apply for examination to a specialist.

The value of crustaceans for humans: positive and negative

It is impossible to say unequivocally about the significance of crustaceans in nature. Of course, an important positive point is that they are all an important link in food chains, capable of filtering out small algae and bacteria from the water. It is known that the symbiosis of a hermit crab with coral polyps brings them a mutual benefit. Many species are consumed by humans. However, some of them are involved in the life cycle of parasites and attack rotifers and their fellow class members.

Thus, crustaceans are animals, which man widely uses in his life, which ensures their important role in nature.