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Cancer: list of representatives of crustaceans

Cancer is an animal of the arthropod type. It can be met mainly in water bodies, but some representatives live on land and in the soil of humid tropical regions. In addition, there are species that parasitize on aquatic invertebrates and fish.

There are so many crustaceans that a whole science called carcinology is devoted to studying them.

Crayfish live both in water and on land

Crustaceans include crayfish, crabs, lobsters, shrimps, woodlice and other living creatures. There are even fixed forms of life, such as bowling and sea ducks.

In total, there are about 73 thousand species that are combined in several classes.

Representatives of the class have several identical limbs that perform many functions at once. With the help of the legs of the animals move.

In addition, with the active repulsion on the limbs sticks filtered food from the water, which then goes into the mouth.

Gill foots got its name because their limbs provide respiratory function. They have a thin cuticle that absorbs oxygen from water.

The list of representatives of crustaceans of this class includes one and a half thousand species. The best studied of them are Artemia and Daphnia. Both are planktonic organisms.

Their nutrition is carried out with the help of the thoracic limbs filtering phytoplankton from water. Artemia are found in shallow sea and mineral lakes, and daphnids inhabit continental bodies of water and rivers with a calm current.

Basically, these organisms are used as food for aquarium inhabitants.

The class has only 12 species. They are united by habitat – all representatives live on the seabed or in the ground freshwater hydrosphere objects.

Cephalocarides are small in size, only 2-3 mm.

Cephalocaride lives on the seabed

On their body stands a large head, partly fused with proportionally developed pectoral segments. It has a primitive antenna, mandibles and four legs. The class representatives have no eyes.

The limbs on the body perform the same functions as those of the toxins.

Cephalocarids feed on the remains of plant and animal organisms or their secretions suspended in water or deposited on the bottom.

The first representative, subsequently named Hutchinsoniella macracan, was found on the Atlantic coast at Woods Hole by the American zoologist Sanders.

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The largest class includes more than 35 thousand species. Geologists found the remains of his representatives, stored since the Cambrian period.

Now higher crayfish are found in fresh and saline waters, as well as on land.

On the head of these creatures are antennas and antennules, the jaws of the mouth apparatus and the eyes. In most of the species, the head merges with several of the eight breast segments, so their forelimbs play the role of the maxilla.

The remaining two-leafy limb located on six abdominal segments. In this class, crustaceans include:

    Crabs.

    Their uniqueness lies in the fact that some species can grow to huge sizes. The most famous Japanese spider crab weighed 19 kg.

    Large species are used for food purposes.

Some crayfish are on the verge of extinction.

  • River crayfish. They have been assigned a protective status in the Red Book of Ukraine as a species under threat of extinction. From the Middle Ages, they were used for human consumption, but for reasons of faith, they are not eaten by Jews.
  • Shrimp Common marine inhabitants, some of their species are developing and freshwater objects. Shrimp sizes range from 2 to 30 cm. Many members of the species are harvested in industrial quantities for human consumption. Shrimp meat is low-calorie, while it is rich in calcium and protein, but Jews and some Muslims abide by the ban on such food. Another use of arthropods – breeding in home aquariums. Interestingly, the Chinese artist Qi Baishi became famous for his masterful depiction of shrimps.
  • Laughs are nocturnal

  • Mokritsy. These creatures live in wet and dark places, are nocturnal. The benefits to humans of them are questionable: in the gardens they eat up weeds and cultivated plants. In case of danger fold into a ball.
  • Bokoplavy. An extensive detachment in which individuals are very different from each other in size, body structure, habitat and lifestyle. Most specimens do not grow more than 10 mm, but there are 28-centimeter representatives who have reached such sizes due to deep-sea gigantism. The differences in the structure consist in flattening, reduction of the abdomen and the number of thoracic legs. Scattered in fresh and sea water, marshy soils. There are forms that parasitize the whales.
  • Thus, higher crayfish are found in various forms almost everywhere.

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    A class of small individuals with a non-segmented oblate body placed in a bicuspid chitinous shell with patterns formed by protrusions. The ostracods have eyes, antennas, legs, a short abdomen and jaws, equipped with distinct tentacles.

    Breathing is carried out all over the body.

    According to geological studies, earlier representatives of the class reached a size of about 9 cm, but now their height does not exceed 6 mm, and more often it does not reach 2 mm. They live only in the aquatic environment, salt or fresh, are found at a depth of 5.5 km.

    They feed on the corpses of animals, and themselves become food for fish.

    One of the most famous representatives of the ostracod is Notodromus monachus. This millimeter pale green body is found in summer and autumn in fresh water.

    Also well studied is Cypris, which is distinguished by a single eye and a lack of circulatory organs.

    The size of the ostracod does not often exceed 2mm

    This class was officially considered extinct for two decades, but in 1979 its representatives were found in Australia, the Caribbean and the Canary Islands.

    Now remipedia is being actively studied. It is established that their body is divided into head and torso, which, in turn, consist of a large number of segments.

    The appendages perform various functions: the antennae with bristles are responsible for smelling, and the claw at the end of the maxilla introduces poison into the body of the victims during the hunt. Recent studies have helped to establish the composition of secretions, which includes digestive enzymes and neurotoxin, present in the venom of spiders.

    Individuals are blind, because they have no eyes.

    The remipedia’s behavior is calm – they slowly swim, feed, filtering water currents. But some species are predatory.

    The most famous representative is the nectopod.

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    The groups of crustaceans, which could not be attributed to any of the well-known classes, were collected in the taxon of the maxillopods, therefore, a number of authors consider it garbage. Nevertheless, representatives of this class also have common signs, for example, the absence of limbs on the abdomen and a reduction in the number of its segments.

    In addition, all individuals have the same number of segments in different departments:

    • on the head – 5;
    • on the chest – 6;
    • on the abdomen – 4.

    The size of arthropods in this class is predominantly small. There are individuals that grow only 0.1 mm. The most famous representatives – cyclops and canes.

    The first crustaceans are a few millimeters in size and live at the bottom or in the freshwater column, where they hunt single-celled and small multicellular organisms. Often they themselves become food for fish and fry.

    They got their name for an unmatched frontal eye.

    Cyclops are a few millimeters in size.

    Adult basses are attached to solid surfaces and lead a fixed lifestyle. This brings great harm to ships, as tons of such organisms can pester them.

    To clean the bottoms have to spend large sums.

    But some travelers appreciate the taste of balus, which is also called sea acorns. Of them prepare the soup and make canned food.

    Some databases do not adhere to the generally accepted classification. The group of maxillopods in them is not recognized and is divided into two superclasses, which, in turn, are formed into several subclasses.

    This allows more systematized knowledge about animals. The main subclasses are as follows:

    1. Carp eaters or carp lice live in fresh or sea water, parasitic on amphibian tadpoles and fish. Previously, they belonged to two units, but now one of them is considered extinct.
    2. Copepods or copepods are the largest taxon whose study is devoted to a whole section of carcinology. The science of copepodia helped to establish that most of the species in the subclass are considered parasitic forms, some of which are quite large and reach 6.5 cm in length. Such individuals reduce the livestock of fish. There are also free-living representatives living in the water column. In contrast, they often become food for fish. They themselves either hunt the younger generations of other crustaceans, or are content with bacteria and algae filtered from the water.

    Copepods often become food for fish.

  • Mistakaridy. Representatives of 12 species in this subclass are so small that they live in the space between the grains of sand on the coasts of America, Africa and the western Mediterranean. Their length does not exceed 1 mm, but at the same time they have a rather developed body, consisting of two sections and six pairs of appendages.
  • Pyatiustok. This subclass has many names – reed worms, pentastomids, lingvatulida. All representatives parasitize in the respiratory tract, nasal cavities, lungs and sometimes the liver of various animals. Their hosts include reptiles, mammals and birds. Some species are dangerous to humans, as they cause invasive diseases.
  • Tantulocalarides Another subclass related to parasites, and as the owners they often choose representatives of other orders of crustaceans. Their owners, in turn, themselves can parasitize on another animal.
  • Pyatiustek parasitic in the respiratory tract of other animals

    This classification is just one of the options for systematizing crustaceans. A single concept has not yet been developed, so the process is delayed due to disagreements among researchers. It is believed that insects should also be included in the subtype.

    If this statement is accepted by the scientific community, all systematization will have to be processed anew: to isolate new common features and to refuse to merge into a taxon according to the principle of the degree of kinship of species.

    The most famous representative is wide-crayfish, widespread throughout Europe. And although the population of this species declined sharply at the turn of the XIX — XX centuries. In Russia, it does not have the status of a vulnerable animal.

    But in the Red Book of the country are three other representatives from the class of higher cancers that are endangered, namely:

      The mantis shrimp, which got its name for bent forelimbs.

      This animal has remarkable claws painted in a bright green color. They have a powerful strike force, so that they can successfully defend.

      The arthropod is a predator, moreover, rather aggressive. Two males fight for a female with serious injuries to each other.

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