Are in which class of fish? The distinctive features, structure, and reproduction of fish

Sturgeon, carp, herring, trout, carp, silver carp, carp - a well-known fish. This list can be endless. But their commercial importance is difficult to overestimate. Indeed, the class of fishes is very diverse. Modern systematics has more than 20 thousand species of these aquatic animals. Due to some characteristics of the structure they were able to master this environment and take it mainstream. In what class are fish, characterized by its structure? To these and other questions you will find the answer in our article.

Characteristics of fishes

No wonder about the self-confident people say: "Feels like a fish in water". Scientists know that the first fish lived in the Silurian period. Outwardly, they were similar to a modern shark with movable jaws, on which the sharp teeth. Millions of years passed, during evolution fish have evolved and acquired a number of new adaptive traits.

As aquatic animals, they all have streamlined bodies, completely or partially covered with scales on the trunk are various types of fins, and respiratory organs are gills. This is a common characteristics to all the members of this systematic unit. But in what class are fish, you can answer, having considered significantly different. At the moment, there are two: Bone and Cartilage.

Buildings

The Body does all the fish is covered with scales. It protects the skin to aquatic environments from excessive friction of the water. Because most of them most of my life spent on the move. Additional protection from friction is a large amount of mucus, which is rich in leather. It helps to survive many unfavorable conditions of temporary drought. Not all species of fish body covered with scales entirely. For example, in sharks it is located in a row on the surface of the body, in appearance Recalling their teeth. The same can be said about many members of the order of the Sturgeon. Most bony fish are protected by scales like strong armor. It performs additional functions: camouflage from predators warning coloration predatory and poisonous species, a designation of the sexual symptom, the reflection of light in water.

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Structure of the fins

Another distinctive feature of fish is the presence of fins. These formations serve as limbs for locomotion in water, and some ancient species even able to crawl through them. The fins are combined into two groups. The first pair are: abdominal and thoracic. They contribute to the balance of the fish in the water column. Are unpaired caudal, anal and dorsal. They work just like the steering wheel, guiding the body of aquatic animals in the desired direction. As a result of evolution from the fish fins formed limbs of reptiles animals.

On the fish body can be easily considered a side line. This unique organ of balance and touch, characteristic only for fish.

Internal structure of fish

The features associated with aquatic habitats, and have organ systems of these animals. Musculoskeletal represented by the skeleton. Depending on the class it is formed of cartilage or bone tissue. All bones of the skeleton of the head are connected fixedly, except for the lower jaw. This allows the fish to easily capture prey. In the division of the skeleton also includes the Gill cover and arcs, the latter of which is attached to a respiratory system fish - gills. The axial skeleton consists of individual vertebrae that are connected between themselves and with the skull still. To tuloviŝnaâ the spine are attached the ribs. The skeleton of the fins is represented by rays. They also formed bone tissue. But paired fins are even and belt. To them are attached muscles, leading them in motion.

The Digestive system of fish through type. It begins the oropharyngeal cavity. Most fish on the jaws are sharp teeth which are used for gripping and tearing food. In the process of digestion are also involved enzymes glands - liver and pancreas. In the processes of extraction and salt metabolism a major role in fish play paired kidneys. They open outward with the help of the ureters.

Fish are cold-blooded animals. This means that their body temperature depends on changes in the environment. This characteristic is determined by the system of bodies of blood circulation. She presented with a two-chambered heart and a closed structure of the vessels. In the course of its movement venous and arterial blood are mixed.

The Nervous system are the brain and spinal cord and nerves. And its peripheral part of nerve fibers. In the brain a particular development reaches the cerebellum. This part causes a rapid and coordinated movements of fish. Senses are able to perceive any irritation, possible in the aquatic environment. Since the eye lens of fishes does not change its shape and position, the animals can see well only at a short distance. But they are able to discern and shape, and color of various items. Body of sound presents the inner ear and is associated with the structure responsible for the balance.

Reproduction of fish also has its own characteristics. These animals are dioecious, with external fertilization type.

What isspawn

The Process of breeding fish is also called spawning. It happens in the water. The female lays eggs, and the male pours her seminal fluid. The result is a fertilized egg. As a result of successive mitotic divisions from it develops the adult.

Sometimes the reproduction of fish is associated with spawning migrations and significant changes in the behavior and structure of fish in this period. For example, pink salmon form large herds, which move from the seas to rivers. During this journey they have to overcome many obstacles, moving against the current. At these fishes on the back forms a hump and the jaw is turned out and bent. Losing a lot of energy, after the process of fertilization, the adults die. Surprisingly, the young fry come back on their own in the same habitat.

Band fish

The Huge species diversity has necessitated the classification of this group of animals. Currently, scientists have precisely determined the grounds on which it is possible to classify the Fish. Systematic affiliation is determined by the presence of a swim bladder, Gill slits or covers, and scales. So it is possible to distinguish between bone and cartilage of fish. There are other signs by which these animals are combined into groups. For example, fish that move to spawning in other habitats, are called anadromous. But, given the scope, distinguish commercial and decorative representatives of these aquatic animals.

Cartilaginous fish

What class are fish with a cartilaginous skeleton, Gill slits opening to the outside? It is easy to guess. It is a cartilaginous fish. They have no swim bladder, so they either live on the bottom, or are constantly in motion. Sawfish, white, giant, whale sharks, ramp-hvostokol... Known to you such fish. The list of dangerous predators, you can continue with the sea devil, electric scat and sea Fox. These sea creatures represent a threat to the life of animals and humans. Although there are among cartilaginous fishes and quite innocent instances. So, the shark, the spiny dogfish feeds on fish and crustaceans. In addition to frightening appearance, no danger to the man it represents.

Bony fish

On the question, in what class are fish, which are most numerous, answer is perhaps every student. Their skeleton is entirely composed of bone tissue. Swimming bladder located in the body cavity, allows its holders to stay in the water column. Gills are covered by Gill covers and not open outside of the individual holes. These signs possess bony fish.

The Value of fish

The Representatives of this super class of vertebrate animals primarily have important commercial value. People are eating their nutritious meat and protein-rich caviar. A number of recipes for various types of does not know account. Fish oil has long been used as a means for the treatment of bacterial and viral respiratory diseases. People annually catches a huge number of individuals and throws them yourself. Meat and bones also get flour. It is used as fertilizer and feed for many domestic animals.

In recent years, the increasing popularity of sport fishing, attracting participants from different countries. And to catch a goldfish, performing all the desires, dreams sure each of us!

So, what class are fish, can be determined by the peculiarities of their structure, organization and way of life.