Bone fish signs and structure of the class, representatives, table, features

The concept of bone fish includes the vast majority of modern fish, and almost the entire commercial fish in the world. This category includes 29,000 species and more than 400 families, as well as several primitive forms.

Bone fish structure


This type of fish belongs to the ridge. The main characteristic of bone fish is the skeleton, at least partially consisting of real bones.

The skeleton of bone fish

Their skeleton interacts with the complex muscle system, which makes the body a segmented, capable of accurate swimming movements. Thanks to such a system, bone fish are well adapted to life in water. It consists of bones and cartilage, which work with muscles, through tendons and ligaments.

The fish skeleton retains the shape of the body and has areas that play the role of the “levers” driven by the muscles with which they are associated. It also provides protection for certain organs and systems, and acts as a place of accumulation of calcium.

There are paired eyes and nostrils, a rotary hole and gill covers on the head, along the back edge of which the border between the head and the body passes. The nostrils of most of them are not associated with the mouth and gills.

In the skull of bone fish, a skull is distinguished, consisting of:

  • A large number of bones motionlessly interconnected;
  • Jaw bones;
  • Gill arches.
  • Jaws serve to passion for food. The gills themselves are attached to the gill arches.

    Skull of zander

    About the eyes, their size and placement on the head depends on the type of fish. In some species they are located below others, depending on behavior and habits in nature. Eyes have a rigid lens that fish can focus with close vision, but can be delayed by muscles for longdistance vision. Many of them see in color, and also perceive ultraviolet light.

    Touch is especially well developed in bottom fish. On the lips and mustache in the epidermis there are sensory cells that capture tactiles, and, of course, taste stimuli.

    The size of the mouth is an excellent indicator of what the fish eats:

  • Most mouths are placed in front of the head;
  • Pisces feeding from below own mouths unfolded down;
  • And, conversely, fish that receive food from above have mouths deployed upward.
  • The heart and blood of bone fish

    Bone fish have a closed blood system with a heart that pumps blood through a single system, throughout the body. The cycle is as follows:

    1. Blood comes into venous sinus;
    2. Then, pumped through the heart and goes to the glys;
    3. From gills to all organs;
    4. From organs back to the heart.

    In most bone fish, the heart consists of four parts: venous sinus, atrial, ventricle and arterial bulb. Despite the fact that the system consists of four parts, the heart of fish is built of two sequentially located cavities atrial and ventricle.

    In the venous sinus, blood devastated from oxygen comes from the body. The valve at the end of the venous sinus opens into the atrium. This is a large muscular chamber that serves as a onesided compartment guiding blood in the ventricle. Ventricle thickwalled muscle bag responsible for pumping blood to the heart. The ventricle is reduced and pushes the blood into a wide tube called an arterial bulb. At the end of the opposite part, the arterial bulb is connected to a large blood vessel called aorta, according to which blood enters the gills of fish.

    Oxygen saturated with gill petals to the organs of the head and body. A complex system of arteries, veins and capillaries circulates blood through the body and returns it to the venous sinus.


    Bone fish breathing can be carried out by gills and light.  If we talk about gills, then this species owns five gill arches. They have a counterflow system, which increases the efficiency of gas exchange (oxygen absorption). Bone fish have four gills on each side. Each of these gills is double, because it has two records that are not separated by a partition. Closer to the inside of the mouth, spikes appear (gill stamens).


    Many fish use a swimming bladder as an additional source of oxygen. The bladder, in addition to the function of bowel movements, often has others: it can serve to create sounds, or their perception. Some species vibrate the arches of the vertebrae to make sounds that intensify the bladder. Others click the stamens of the gill arches to make sounds.

    As mentioned, the bladder is also used for the perception of sounds, since two inner ears are reported with it through the “Weber” bones. Most species can perceive signals below 1 kHz, some improved their hearing using such structures and expanded the range of up to 5 kHz, or even more.

    Thus, the hearing aid is as follows:

    1. Inner ear;
    2. Endolymphatic bag;
    3. “Weberians” bones;
    4. Swimming bubble.

    As “sixth feelings” in these fish are the organs of perception of water flow, which pass in the middle of most of the body length. They consist of a series of recesses on the skin containing sensory cells with hairs, excited when the flow changes.


    Most bone fish are covered with scales. Their scales formed for a very long time. There are four types of it:

  • Cosmoid;
  • Cycloid;
  • Cthenoid;
  • Ganoid.
  • Cosmoid scales are almost never found today. It can be seen on petrification. The most common form of fish scales is elasmoid scales. This is a thin plate that you met in most fish. It can be of two types: “ktenoid”, which has a set of small teeth along the back edge, and “cycloid”, which is simply rounded on the outer edge. Ganoid scales came from cosmoid scales and evolutionarily more old than the previous two. Found on scourges, sarganes, sturgeon and reed fish.

    Not all fish have scales, for example, in some species, such as a sun fish, it is not at all. Other species, such as ordinary eel, do not seem to have scales, but they have microscopic scales, deeply built into their dermis. Even those fish who have scales, she does not always cover the whole body.


    In some species of bone fish that swim slowly, spikes on the body are found. They perform a protective function. For example, spinoros own three spikes on their backs (hence the name). They can calmly hide between the stones and not allow to swallow themselves to the predator.


    Most bone fish emit mucus throughout the body, which protects them from infections. In some cases, it is food for fry.  Sometimes, this is a great way to “hide” from predators, the basis of the search for the victim of which is the sense of smell: mucus simply hides smells.


    The brain of fish consists of the following parts:

  • Front is responsible for the sense of smell;
  • Medium vision, training and movement;
  • Rear coordination of equilibrium, movement and tone.
  • Digestive system

    The system can be divided into:

  • Oral cavity, which is based on teeth. They are very diverse. Typical small, conical shape, are located on the edge of the jaw, attached with ligaments, which provides them with some mobility, useful for seizure of prey. Sometimes scientists find teeth on gill arches, and sometimes heterodontics manifests itself, that is, teeth of various shapes.
  • Zaber passage a throat with slots to the gills, usually with trap formations at the end. This also includes the pharyngeal bones;
  • Esophagus;
  • Stomach. These fish have either a U-shaped stomach, or it does not have it at all, like carps. If it is available, at the end of the system there are pyloric curtains.
  • The middle part of the intestine (the length varies depending on the nutrition; at first, the blind pipe tubes can depart from it with 0 to 1000, the function of scientists is unclear; the liver and pancreas are often not separated);
  • The back of the intestine is for herbivores, sometimes with a blind intestine.
  • The most important glands of the digestive tract in bone fish are liver and spleen.

    The origin of bone fish

    Today there are more species of bone fish than any other group of ridge. The first bone fish appeared about 410 million years ago with placerma. The evolutionary appearance of bony fish ultimately led to the appearance of terrestrial vertebrates, with bone skeletons. The respiratory system of bony fish has become a feature that ultimately evolved into the lungs. Thus, bone fish are direct ancestors of a person.

    Signs of bone fish

    Most of the fish on Earth belong to bone, which makes them the largest group of ridges that exist today. They have the following signs:

  • The most obvious is the skeleton built of bones.
  • Light or swimming bladder, which helps the body create a balance between immersion and swimming: either filling or emitting gases, such as oxygen. Gas volume control in this organ helps Pisces regulate their depth.
  • Hinged segmented rods supporting fins.
  • The lid over the gills, called the gill cover, helps them breathe without swimming.
  • The ability to see in color, unlike most other fish.
  • Features and characteristics of bone fish

    Internally, from cartilaginous fish, they differ in the following: while they have a spiral valve in the intestines, it is replaced by pyloric curtains in bone, and there is no rectal gland. In the respiratory system, gills appear inside the gill chamber and are covered with a lid.  In some groups, the swimming bubble turned into a kind of lung, which also serves for swimming at a certain level of water, or for vertical movement. Both structures: light and swimming bubble, mutually exclusive, that is, when one exists, the other cannot, and vice versa.

    In addition to the internal skeleton, they have a bone cover on a dermis, in the form of a scales, better known as a dermatosklet. These scales play an important role in the classification, since their type and quantity are used as distinctive features of various groups of bone fish.

    As for the fins, scientists mainly distinguish a couple of abdominal and pair of breast fins, and one, or several, dorsal fins. These fish also have a tail fin.

    Actinoptygii and Sarcoptygii

    There are two different classes inside the group of bone fish: “Actinoptygii” and “SarcoptyGii”.

    Actinoptygii (radiant fish) is a type of bone, in which radiation fins consist of a bone skeleton. Their skull is mostly cartilage, and they have a pair of gill holes that are connected to the outside, protected by a gill lid. Scales are rudimentary, some species are not even absent.

    They can have both paired or unpaired fins with long skin rays. Jaws with enamel teeth. Scales can be of a ganoid type (in primitive), cycloid, or ktenoid. Breath is carried out by gill lids. Some species have a swimming bubble that can be connected to the esophagus. This is an organ whose flexible walls allow you to absorb gas, providing buoyancy. The circulatory system consists of a heart with a venous sinus, atrial and an undivided ventricle; They have simple blood circulation and usually 4 pairs of aortic arcs. The nervous system is represented by the brain with olfactory shares, the auditory shares, the large brain and the cerebellum; 10 pairs of cranial nerves.

    Sarcoptygii (bladestep) bone fish with paired fleshy, or lobed fins. The basal skeleton of fins is short, they are supplemented with blades. These fins are very similar to the fins of some amphibians, which indicates the evolution of fourlegged from marine creatures.

    They are characterized by the presence of paired chest and abdominal fins, the base of which has small skin rays, as well as muscles that ensure the movement of these fins. Jaws with enamel teeth are usually reduced to crushing plates located in the sky.

    Gills are supported by bone arches and covered with a lid, like the first species. There is a gas bubble that is used for breathing and maintaining buoyancy. The circulatory system includes a heart with a venous sinus, two atrium, partially divided by the ventricle and arterial cone; Double blood circulation, with pulmonary and system contours, usually with five aortic arcs. Nervous system with olfactory shares, large brain, cerebellum and visual share; 10 pairs of cranial nerves.

    Representatives of bone fish

    Acne is characterized by a serpentine body, devoid of abdominal fins. Spinal, tail and abdominal fins grown into one, devoid of hard rays. They live in the sea. The exception is European eel, which lives in fresh waters, returning to the sea only for the period of spawning.

    European eel

    Herring. Previously, this included many other detachments that are considered independent today, for example, a large group of types of salmon. Today, herring belongs mainly herring, anchovies and sardines living in the seas. The herring has a tube connecting the swimming bladder to the esophagus, and the abdominal fins are located back, far from the shoulder girdle. Soft rays in the fins.


    Salmon fish. Representatives of the salmon detachment are usually found in the waters of the Northern Hemisphere. Their characteristic feature is a small luminous fat fin, between the dorsal and tail. These fish live both in the seas and in fresh water, but multiply exclusively in fresh.

    Caspian salmon

    The following features are characteristic of carp and catfish: they belong to the group of phizosta, in the case of injury, they are distinguished through special skin cells, informing their companions about the approaching danger. They have a weber apparatus that functions like auditory bones of vertebrates: a swimming bladder acts as a drum membrane, absorbing sound waves.



    The stony “sea robbers”, most often accompanying herring, are the few in the view of the view. They are distinguished by a very flattened, diskshaped body from the sides, hard, or soft rays in fins, and thanks to the elongated axillary bones, moving forward mouth.

    A number of strples are found both in sea and fresh waters. A characteristic feature of fish forming it is the presence of separate spikes in front of the dorsal fin, and the body is more or less covered with bone plates. It includes sea skates. They are characterized by an elongated tubular shape of the body, ending with the mouth of the “pipette” form through which food is absorbed.

    Sea Horse

    The largest detachment with numerous subcutters and families of mainly sea fish is perch. These are all fish in which the floating bubble is not connected with the intestines. Often both of their spinal fins are connected; front from hard, rear from soft rays. Cephalopods and lips are distinguished by excellent coloring, and Persian can change the floor throughout life.

    River perch

    Cambalas are represented in European waters by four families: rocky, flounder, linguistic and salt. In fact, this is sea fish, although flounder is found in fresh water. Typical for these fish is the asymmetric body structure. During the period of youthful growth, as maturity reaches, the initially symmetrical young begins to take asymmetric shape. During this time, their mouth and eyes “wander” on the top of the body, the lower side of the fish sticks to the ground, starting the bottom life of the fish. They spend youth in shallow water.


    Representatives of the detachment of bacons are distinguished by peculiar forms: the head and front of the body are very large, and the chest fins are turned into a specific crawling organ. The elongated radius of the spinal fins ends with a bait, with which they catch their prey.

    The detachment of the needlefree ones includes the following families: spinoros and sunny fish. They have a discable body that can reach up to 3 meters in diameter. The body of the needlebell is covered with bone plates. They are all characterized by a big head with a small mouth.

    Habitat and distribution

    Bone fish can be found in the waters around the world, both in fresh and salted. Sea brown fish live in all oceans, from shallow water to deep water, both at cold and warm temperatures. Their life ranges from several months to more than 100 years.

    An extreme example of the adaptation of bone fish is the Antarctic ice fish that lives in the waters so cold that antifreeze proteins circulate in its body so as not to allow it to freeze. Almost all freshwater species that live in lakes, rivers and streams also include bony fish. Solar fish, perch, catfish, trout and pike are examples of bone fish, like freshwater tropical fish that you buy for your aquarium.


    The diet of bony fish depends on the type, but may include plankton, crustaceans (for example, crabs), invertebrates (for example, green sea urchins) and even other fish. Some of the bony fish are virtually omnivorous, eating all species of animals and plants.

    Green Sea Hedgehog


    The behavior of bony fish varies greatly depending on the type. Smaller swim flocks for security. Some, like tuna, constantly swim, while others (stone fish and flounder) spend most of their time lying on the seabed. Some, such as moraines, hunt only at night; Others, like butterfly fish, do it during the day; and others are most active at dawn and at dusk.

    Propagation of bone fish

    In many species, it is very difficult to distinguish between males and females. In others, the floor can change throughout life, they are called consistent hermaphrodites. Fertilization external, so males do not have a copulative organ, with some exceptions to which internal fertilization occurs, in these cases the males transformed anal fins in order to be able to transfer sperm to the body of the female, and thus achieve fertilization.

    Most bone fish are oviparous, although there are cases. Among the bone eggs, there are two types:

  • dense, or demersal eggs that fall to the bottom;
  • Eggs that swim and dissipate on water (Pelagic).
  • Masonry can reach millions of eggs to compensate for the high mortality of the offspring.

    Propagation habits are very complex, including actions such as the construction of a nest, or care for the brood. Some species take care of the eggs until they hatch, although this is very common, since most of the bone fish, after deposit, throw eggs to the mercy of fate. The propagation of these fish occurs at a certain time of the year. Periods depend on each species and can vary from several times a year, to every month.

    In some species of fish, sexual dimorphism is observed: the male is much smaller than the female, and all his life lives as a parasite attached to it.

    The value of bone fish

    They are an important link in trophic chains. On the one hand, bone fish are consumers, and on the other, they themselves are an important source of food for many animals. They participate in the cycle of substances in aquatic ecosystems.

    Fish is used by man for economic purposes on an industrial scale:

  • is a source of delicious and healthy meat consumed in various types (fresh and frozen, dried, smoked, fried or canned); fish meat has high food value (fish is a source of protein, calcium, iron, phosphorus, vitamins and omega-acids);
  • Fish waste (bones, head, fat) is processed into fish flour (used as fertilizer and feed for livestock) and oil (used in the production of soap and as lubricants);
  • Fish oil, obtained from the liver of reservoir fish, is rich in omega acids and vitamins A and D; It has various applications, for example, with vitamin deficiency, against rickets, in dermatology (oil ointment), as food fat (in the northern population) and before the fuel for lamps;
  • A valuable delicacy is considered caviar, t.e. caviar of some types of bone fish (mainly sturgeon, salmon and cod);
  • Many hold small aquarium fish at home, and larger and most luxurious halt in special pools.

    The results of observations of them are used for bioidication, that is, tracking the influence of adverse environmental changes, as a result of human economic activity, to living organisms, and their reactions to these changes. Regional research on fish helps to determine the degree of degradation of the environment in the area, especially the purity of water, and help maintain the number of species.

    Class “Bone fish” table

    The name of the detachment
    a brief description of
    Sturgeon There is a similarity with cartilaginous fish, a skeleton of a bone-chryashchev; The body is elongated, the head begins with a compacted snout, on the bottom there are two pairs of antennae, a mouth in the form of a transverse semimoon slit; Opestr, Beluga, Sevryuga, Sterlad
    Selderyshaped Elongated body compressed from the sides; The color of the back is dark, and the abdomen is white with a silver tint; paired and unpaired fins are soft, the side line is invisible; Volzhskaya herring, Pacific herring, Black Sea sprat, herring of the Black Sea-Azovskaya, Kaspian sprat
    Salmonshaped They live in the seas, feed, reach puberty, but enter the rivers for propagation Symga, trout, room, kizhum, pink salmon, smelt
    Carpshaped There are vegetable, predatory and omnivorous Neon, Council, Bulk, Rybets, Piranha
    Perchshaped Common in reservoirs of all continents and oceans; the presence of two spinal fins with sharp thorns; Almost all representatives are edible Fish-fuel, teeth, cockerel, pike perch, mackerel, perch
    Dipnoi Located in shallow rivers with a slow course; fish are considered ancient; well adapted to life in reservoirs and can switch to pulmonary breathing Protoporters, Rogozub, Lepidosiren
    Karestelny Propagated by livestock; have skeletal formations in paired limbs, equipped with powerful muscles. Coelacanth

    Bone fish biology lesson for grade 7

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