Orders of cartilaginous fish table. Question. Systematics of cartilaginous fish, the main orders of the shark. Groups of the Cartilaginous and their characteristics
FISH class cartilaginous(Chondrichthyes) Class FISH cartilaginous (Chondrichthyes).
subclass. Lamellar fish (elasmobranchh) Sharks (selachomorpha) Superorder Skatha (batomorpha) Superorder Fishes, solid-cranial or whole-headed (Holocephali) Subclass: Elasmobranchii - Lamellar fish. This is the order with the greatest diversity of species among sharks. Appeared during the Jurassic period, representatives are found from the intertidal zone to the ocean depths almost everywhere. The external distinguishing features are very variable, but all are characterized by the presence of five gill slits, two dorsal fins (except for the single fin cat shark), and an anal fin. Reproduction methods are also very diverse - there are oviparous, ovoviviparous and viviparous species. Some are characterized by oophagia. Multi-toothed. Appeared in the Triassic period, and represent a detachment of bottom sharks, leading a nocturnal lifestyle. Their external features are a dense body, two spined dorsal fins, and an anal fin. Distributed from the intertidal zone to the continental shelf. All species are oviparous. Polygillus. The detachment is the oldest among the existing sharks - it was formed during the Permian period. Consists of two families, differing in body shape - eel-like in frilled sharks and "traditional" torpedo-shaped in multigill sharks. Both families have six or seven branchial slits, one dorsal fin, and an anal fin. Mostly distributed in the cool depths of the tropics, ovoviviparous. Lam-like. Appeared in the Jurassic period. This order is dominated by large pelagic species. They are torpedo-shaped, with five gill slits, two dorsal fins, and an anal fin. Distributed from intertidal zone to deep ocean waters, ovoviviparous. Wobbegong-like. Appeared in the Jurassic period. Distributed in warm and tropical seas from intertidal to deep waters. With the exception of the whale shark, all species live on the bottom. They have five gill slits, two dorsal fins, and an anal fin. Among the species are oviparous, ovoviviparous and viviparous. Some also have oophagia.
Saw-shaped. Perhaps the most easily identifiable unit. It appeared during the Jurassic period. Sharks of this order are distinguished by a specific long, sawtooth muzzle, dotted with teeth, as well as the absence of an anal fin, two dorsal fins and large spiracles. They live at the bottom, ovoviviparous. Katraniform. Appeared in the Jurassic period. This order is widespread and found all over the world, including - the only shark - in latitudes close to the poles. They live at great depths. Representatives of the detachment have a torpedo-shaped body, five gill slits, two dorsal fins, and an anal fin is missing. Ovoviviparous.
Squat-like. Appeared in the Triassic period. The habitat is usually the silt or sand of the continental shelf and intertidal zone in cool temperatures, as well as deeper areas in tropical waters. Sharks of this order are distinguished by a wide flattened body, a short muzzle, five gill slits, large pectoral and pelvic fins, and the absence of an anal fin. Outwardly, they resemble stingrays, but the difference is that the gills open on the sides of the body, and not below, and wide pectoral fins are clearly visible, clearly separated from the head. All species are ovoviviparous Order: Carcharhiniformes Compagno - Carhariniformes Order: Heterodontiformes Berg - Mottoid Order: Hexanchiformes Buen - Polygillaceous Order: Lamniformes - Lamiformes Order: Orectolobiformes Compagno-like Squid-like Squid-like Squid-shaped
52 taxonomy of cartilaginous fish, a variety of rays. Class FISH CARRYING (Chondrichthyes).
subclass. Elasmobranchs (elasmobranchh) Stingray rays (Anacanthobatidae) Rhombus rays (Rajidae) Rhinidae Rhinobatidae rays (Rhinobatidae) Shark-tailed rays (Rhynchobatidae)
Representatives of this order have a strongly flattened rhomboid body, on the pelvic cartilages there are peculiar outgrowths and traces of gill folds in the spigots. In the skates of this order, tail spines are absent, and the caudal fin is greatly reduced. They are typically benthic. Also, some rays of this order have large spines along the middle of the body. The color of individuals depends on the color of the soil of the environment in which they live. Stingrays are predominantly nocturnal, and during the day they are not very active and burrow into the ground, leaving only their eyes on the surface. They predominantly live in coastal waters, although deep-sea rays also exist.
Today this order is the most numerous and includes about 200 species of rays. Distributed everywhere, however, the greatest diversity is reached in the polar regions and regions with a temperate climate. In Russian waters, the detachment is represented by only one family - the family of rhomboid rays (Rajidae). They feed on small fish and benthic invertebrates. Reproduction takes place by laying cornea-coated eggs.
53 question The main features of the organization. Cartilaginous fish, characteristics of lamellar and whole-headed fish. Lamellibranch * (Lamellibranchiata) - a class of molluscs type. Characteristics of P.: the body is usually quite symmetrical, almost always laterally compressed, laterally covered by two large mantle lobes, between which there is a large mantle cavity enclosing the lower body and leg of the animal, two gills attached to the sides of the body, and 2 pairs of triangular oral lobes; a shell of two lateral valves connected to each other at the dorsal edge and brought together by 1 or 2 muscles extending from one valve to the other; detached head, cephalic tentacles, pharynx, jaws and radula are absent; paired kidneys and gonads; a heart with 2 atria; dioecious or hermaphrodites, exclusively aquatic animals, freshwater and marine, mostly free, less often, in adulthood, attached. Despite the considerable variety in appearance and structure, P. represent a very natural group, easily distinguishable from other representatives of the mollusc type. In the vast majority of P., the body is quite pronounced two-sided symmetry; less often, symmetry is disturbed by the unequal development of the right and left halves due to the fact that an adult animal is either attached to underwater objects (usually grown) on one side (for example, an oyster), or usually lies on one side (for example, some species scallop - Pecten); at the same time, the valves differ in size, shape, thickness, color, sculpture, and the internal organs also represent a more or less significant deviation from symmetry. The shell valves are for the most part large and can completely cover the body of the animal, but sometimes they are very small (for example, in a woodworm; see Molluscs, corresponding fig.). In addition to the shell valves, the mantle can secrete lime deposits in the form of additional plates or a layer lining the channels in which the mollusk (woodworm) lives, or in the form of a tube that replaces the shell, while the minor valves of the latter merge with the tube (in Kropilets - see. , or watering jars - Aspergillum). On the dorsal edge of the valve, the so-called. a strand (ligamentum), which, when the muscles contract, that is, the shell is closed, is compressed, and when the muscles are relaxed, it pushes the flaps. In addition to the strand, on the dorsal edge of the valves of some P. there is a lock - more or less developed protrusions and depressions of the inner surface of the valves, the location and shape of which are such that when the valves are closed, the protrusions of one enter the depressions of the other, facilitating the tight connection of the valves of the closed shell. On the inner surface of the valves, a line is visible corresponding to the edge of the mantle, and the attachment points of 1 or 2 strong muscles bringing the valves closer together. Adjacent valves are not always completely in contact: they often leave a more or less significant opening (gaping shells) open. Both lobes of the mantle can be completely free at the front, lower and rear edges, or be spliced together over a more or less significant extent in one, two, rarely three places. Due to the fusion or sometimes close adhesion of the mantle blades to each other in certain places, the entrance to the mantle cavity splits into 2-4 sections: through the rearmost one, water that washed the gills is removed, together with feces and excretion products, through the next, water enters the mantle cavity, a leg extends through the front opening; behind the latter, there is occasionally another small hole, probably corresponding to the byssus, if there are only two holes, then water is discharged through the back, water is introduced through the front, and the leg with the byssus extends. The edge of the mantle can be simple or thickened with special sense organs (papillae, tentacles, eyes). The edges of both posterior openings often lengthen, forming two tubular siphons: through one (lower) water enters (gill siphon), through the other (upper) it exits (anal siphon); siphons can be many times the length of the shell; sometimes they are more or less connected to each other (see corresponding fig.) The animal's body, devoid of a separate head section, ends from below in a muscular, more or less strongly developed, but sometimes rudimentary leg; most often the leg is conical or wedge-shaped, but in some P. of the most primitive structure, the leg is equipped with an extended flat sole (in Nucula, Leda, Yoldia). Many P. have a special gland in the leg that secretes dense filaments similar to horny ones - the so-called Byssus, with which the animal can temporarily attach itself to underwater objects. The order True lamellar-gill family includes more than one hundred families and is divided into four suborders: Split-toothed (Schizodonta), Multi-toothed (Heterodonta) - the largest in terms of the number of families, genera and species, Adapedonta and Anomalodesmata. ) Possessing a number of unique features, representatives of this subclass of fish, in addition, in the most bizarre way combine the features of the plate-gill (Elasmobranchii) and bony fish (Osteichthyes). It is no coincidence that the great Linnaeus gave one of the genera the name "Chimera". With lamellar gills (selachia), they are, first of all, related by the presence of paired copulatory organs (pterygopodia) in males; the ability of females to lay large eggs enclosed in horn capsules; the presence in the external skeleton of placoid scales ("skin teeth") and the complete absence of ossification of the internal cartilaginous skeleton, some elements of which are sometimes strengthened due to calcification (should not be mixed with ossification). In addition, in the heart of modern fused cranials, as well as of lamellibranchs, there is an arterial cone, equipped with three rows of valves; a spiral valve passes through the intestine; large nostrils are brought close to the transverse mouth and communicate with its posterior corners with the help of furrows dissecting the upper lip; the outer lobes of the fins are supported by a large number of thin elastoidin filaments (elastotrichia), while in teleost fishes their homologous fin rays are replaced by bony rays (lepidotrichia); the fleshy lips are supported by labial cartilage, and, like the laminobranchs, the brain and heart are arranged and the swim bladder is initially absent.
Question 54 General characteristics of the Bone class, the system up to subclasses. The bony fish class represents the largest superclass of fish. It includes about 20,000 species. This class is common in almost all water bodies of the surrounding world. The living conditions of bony fish are very diverse, which explains the richness of this group of species and their diversity. The Osteichtyes class consists of a wide variety of fish species. Their scales are ctenoid or cycloid, as well as serrated or smooth, depending on the shape. The class of bony fish is several times more diverse than the class of cartilaginous fish. The skeleton is predominantly bony. The appearance of the skeleton is possible in two main ways. The initial type of ossification is the integumentary or cutaneous bones. Embryonic ossification occurs in the connective layer of the skin, regardless of the presence of cartilaginous components of the skeleton, since it is only attached to them. Based on the above-described features, the development of the integumentary bone often has the form of plates. In addition to the presence of integumentary bones, the skeleton of fish has cartilaginous or chondral bones. Their occurrence occurs in the embryonic period due to the replacement of cartilage with bone substance that produces osteoblasts. As chondral bones appear, the skeleton of fish gradually ossifies, which makes its own adjustments to the general structure of the skeleton. Due to the formation of integumentary ossifications, new elements of the skeleton appear, which significantly complicates its overall structure. There is a reduction in the intercostal septa of the respiratory apparatus. The gill petals are located directly outside the branchial apparatus. Most species of the bony fish class have a swim bladder. Almost all species of fish of this class reproduce by external fertilization. The laid eggs are small, without horn-like shells. A negligible number of bone-class fish species have live-born offspring. The classification of bony fish is so complex that at present there are several views on the taxonomy of this group. Subclass Ray-finned fish (Actinopterygii) Subclass Lobster-finned fish (Sarcopterygii).
55. Characteristics of the Blade: features of the organization, their origin and evolution.
Lobe-finned (lat. Sarcopterygii) or choanic - a class of bony fish. The axial skeleton is based on an elastic chord. Known from the early Devonian (300-400 million years ago), they combine both archaic and progressive features. The superorders are lung-finned and cross-finned superorders. Lobe-finned fish (in contrast to ray-finned fish) have moved to living in inland water bodies, their outgrowth of the esophagus turns into a lung, the leading analyzer is the sense of smell, and compared to other fish, the brain changes. The scales are cosmoid or bony. Throughout life, the notochord is preserved, surrounded by a dense connective tissue fibrous-elastic sheath. The upper and lower arches develop, and in the caudal region there are sometimes underdeveloped vertebral bodies (in some fossil groups they were better developed than in living species). The skull is amphilistic or autostylish. Scaly bone is present among the integumentary bones of the skull. The tail is heterocercal (fossil) or dificercal. Paired fins with a fleshy blade covered with scales at the base; their skeleton is of a bead type. There is a cone arteriosus in the heart. The intestine has a spiral valve and opens into the cloaca. As outgrowths of the ventral side of the initial part of the esophagus, one or two bubbles are formed, which perform the function of the lungs. Known from the Lower Devonian. Superorder cross-finned fishes (CROSSOPTER YGIMORPHA). The cerebral skull is divided into two parts - the olfactory and the cerebral itself, movably connected to each other. The degree of ossification of the skull varies, integumentary ossification is developed. The skull is amphistilic; in some species, a transition to autostyly is planned. The secondary jaws are well developed, the teeth are strong and sharp. There may be vertebral bodies with a shortened central axis and a well-developed basal element at the base. They occur from the Lower Devonian in the form of several, already clearly limited groups. Freshwater predators that have repeatedly entered the seas.
"Commercial fish" - Groups of commercial fish. Order Salmoniformes. Salmon. Detachment Codfish. Carps. Cod-like. Detachment Carps. Sturgeon. Variety of commercial fish. Detachment Herring. Detachment Sturgeon. Herring-like.
"Fish Class" - The fish organism is complex. What kind of environment do fish live in? The value of fish. Internal structure of the fish body. What groups is the vertebrate subtype divided into. Answer the test questions. What have we learned. The external structure of fish. The main organ systems of fish. Sense organs. Respiratory system. Habitat. What group of living organisms are we studying?
"Fish biology" - Aquaculture has two main areas. Biology and pathology of fish. The main production and technological processes in pond fish farming. The purpose of the discipline: And second - artificial reproduction of aquatic biological resources.
"Amazing Fish" - Biology Presentation On Topic: Amazing Fish. Angler. Whale shark. The angler is a predatory sea fish. There is no chin barb, and there is a dysfunctional gut. Wart venom is extremely dangerous. Sailboat. Fish-dragon. The idiakant, or "dragon-fish", is a long flexible fish. Armored pike. This fish lives at depths of 600-1200 m on the coast of Australia and Tasmania.
"A fish is an animal" - The instinct is prophetically blind. Detachments. The source of glue production. Make a crossword puzzle. Name the fish. Classes of fish. Variety of fish appearance. Scat. Number of species. Finish the proverbs. Choose the correct judgments from the proposed ones. Large aquarium. General characteristics of the class of fish. Pipefish. Classification of fish.
"Variety of fish" - Birds. Are growing. Flounder. Cockerel. Mystery. Fish is the moon. Omnivores. Skate. Predators. Fins. Are developing. For parents and children All clothes are made of coins. Catfish. Breathe. Marine. Fish is a hobbyhorse. Crucian carp. V - already knew + - learned new? - I want to know. Scales. 2 legs, feathers, wings, beak breathe lightly. Fishes. Head. Animals.
There are 18 presentations in total
1. Draw a table in a notebook and fill it out as you study the orders of bony fish
2. Remember the features of the structure of cartilaginous fish. What features of sturgeon fish emphasize their resemblance to cartilaginous fish?
The spine keeps the chord
3. Sturgeon fish are also called anadromous fish. Explain this variation of the name
They spend most of their life in salt water, climb into rivers for spawning
4. White Sea herring spawning in summer (“summer”) breed under conditions of significantly higher activity of predators than herring spawning in spring (“spring”). Scientists have found that herring of one of these groups spawn from 2.3 thousand to 21 thousand eggs, while others from 9.2 thousand to 62 thousand eggs. Determine the fertility of the "summer" and "spring" herrings. Argument your answer
In summer - from 9, 5 to 61 thousand calves
Spring - from 2 to 20 thousand calves
Yes, most salmon species can be considered anadromous
6. Why are piranhas dangerous for animals and humans?
Piranha teeth allow large chunks of meat to be pulled out of the body of prey
7. Explain why one type of eel is called electric. Why does he need electrical discharges?
Electrical discharges are used to protect against enemies and to obtain food.
8. What feature in behavior and respiration of electric eels allows them to live in reservoirs with a minimum amount of oxygen?
There are areas of tissue that allow you to absorb oxygen
9. List the types of fish farmed in fish farms
Carp, tench, pike, walleye, saberfish
10. Name the species of fish of the order carp, bred in aquatic aquariums
Barbs, labeo, goldfish
11. How can one distinguish fish of the order perchiformes by the outward appearance of the structure?
The pelvic fins are located under the pectorals. The fin is shaped like an undivided sharp thorn
12. Complete the scheme "Squad Perch Families"
1.stone perch
2.perch with childbirth
3. horse mackerel
4.sea crucian carp
5. rotosthenic
6. catfish
7.gobies
8.sailboats
13. Review figures 94 and 95 of the textbook (pages 111 and 112). Write down the species names of the fish of the orders Carp and Perch, which you caught in the rivers and lakes of your area
Order Carp: bream, carp
Perch-like order: perch, pike perch
14. Consider the pictures. Write down the numbers of the fish included in the corresponding orders
Sturgeon squad: 6, 3
Herring Squad: 5, 7
Order Salmonidae: 10, 8
Carp squad: 2, 4
Percoid squad: 1, 9
15. Consider the pictures, sign the names of the fish
16. Why are protoptera, lepidosiren, cattle-toothed fish referred to as lung-toothed fish?
They breathe in water and on land
17. What do the habitats of lungfish living in Africa, America and Australia have in common?
They have a prototype of the lung, they can withstand the drying out of the reservoir
18. What changes in the fins of coelacanths make it possible to call them cross-finned fishes?
Paired fins serve for support, represent blades consisting of several brush-like segments
19. Remember the similarities between sharks and cross-finned fish
Two-chambered heart, live in water. axial skeleton in the form of a chord
20. Explain why lungfish and cross-finned fish can be considered transitional forms between aquatic and terrestrial animals
In the absence of water, they can switch to pulmonary respiration.
Fish are aquatic animals. In order to actively move in the aquatic environment, the body of the fish has a streamlined shape.
The body of fish can be divided into:
- head
- torso
- and tail
The border between the head and the body is the posterior edge of the operculums, and the border between the body and the tail is the anal fin.
Insert Flash
From above, the body of the fish is covered with skin, which consists of:
- corium or dermis
- and a multilayer epidermis (as in all vertebrates).
In the epidermis there are numerous mucous glands, on top of the epidermis in most fish is covered with scales.
The streamlined body shape, mucous glands and scales help the fish move quickly and easily in the water.
They move with the help of torso bends and with the help of paired pectoral and pelvic fins, which are mainly responsible for vertical movement, as well as an unpaired caudal fin, which acts as a rudder.
Also, the dorsal and anal fins, which stabilize the body of the fish in an upright position, are also unpaired fins in fish.
Fins:
- paired chest
- paired abdominal
- unpaired dorsal (1 or more)
- unpaired anal
- unpaired tail
Musculoskeletal system of fish
Insert Flash
Fish have a well-developed skeleton, which is divided into:
1.axial skeleton, which includes:
- spine,
- skull or head skeleton
- and ribs
2.skeleton of the limbs, which includes:
- the skeleton of paired fins (free part and belts)
- and the skeleton of unpaired fins.
Fish skeleton - the picture shows the skeleton of a bony fish
The skeleton of fish consists of the skull, spine, ribs and the skeleton of paired and unpaired fins
In representatives of the Cartilaginous fish class, the skeleton consists only of cartilaginous tissue. In representatives of the class Bone fish, both cartilaginous and bone tissue are present in the skeleton.
The spine performs supporting and protective functions - the spinal cord is protected by the arches of the vertebrae. The spine consists of two sections - the trunk and the caudal. The vertebrae of the trunk spine have lateral processes to which ribs are attached.
The skeleton of the head is represented by the cranium, to which the jaws and branchial arches are connected, and in bony fish, also the branchial covers. Cartilaginous fish have no gill covers.
The digestive system consists of the mouth, pharynx, esophagus, stomach and intestines, into which the ducts of the liver and gallbladder, as well as the pancreas, open. The intestine ends with the anus, which opens in front of the anal fin.
Only bony fish have a swim bladder
Fish have a swim bladder, which is an outgrowth of the intestinal tube. The swim bladder is filled with gases and can expand and contract. In this case, the specific density of the body changes and the fish can move in the water column in the vertical direction. Only bony fish have a swim bladder; cartilaginous fish do not.
Respiratory system of fish
Fish breathe with their gills
Respiration of fish is carried out with the help of gills. Water enters the mouth, then water from the pharynx passes through the gills into the external environment, while the blood vessels located in the gill lobes are saturated with oxygen.
Circulatory system of fish closed type
The circulatory system has one circle of blood circulation in all fish, except for lungs. There is a two-chambered heart, consisting of an atrium and a ventricle.
Insert Flash
The nervous system consists of:
- the central section, which is represented by the brain and spinal cord and
- the peripheral section, consisting of the cranial and spinal nerves.
The brain in fish, like in all vertebrates, consists of five sections.
The nervous system of fish consists of the brain and spinal cord and nerves extending from them.
The olfactory lobes of the forebrain are well developed, since the organs of chemical sense - smell and taste - play a very important role for fish. The visual centers are located in the midbrain.
The cerebellum is also well developed, which is responsible for a variety of movements. There are lateral line organs that allow fish to determine the direction of water movement. There are organs of balance and hearing.
The excretory system of fish consists of the kidneys, ureters and bladder.
The excretory system is represented by paired ribbon-shaped kidneys, ureters and the bladder, which opens with the urethra, which is located next to the anus.
The reproductive system of fish
Most fish are dioecious, males have two testes, and females have two ovaries. Females lay eggs (eggs) into the water, males - sperm. Fertilization takes place in the external environment.
Fish eggs - eggs
In many cartilaginous fish and in some bony fish, fertilization is internal; females give birth to fry.
Fish taxonomy
At the moment, about 30 thousand species of fish are known. The taxonomy of fish is quite complex, we will consider a somewhat simplified diagram. Currently, in different sources, you can find various variants of taxonomy.
Classes cartilaginous and bony fish
The superclass of fish includes two classes - Cartilaginous fish and Bony fish.
The skeleton of cartilaginous fish, as the name suggests, consists only of cartilaginous tissue.
Cartilaginous fish include sharks, rays and chimera
To the class of Cartilaginous fish relate:
- detachment Sharkiformes,
- squad Skaty
- and the Chimera squad.
For cartilaginous fish, the following features are characteristic - they have no swim bladder, no gill covers.
Cartilaginous fish - sharks and rays
The order Bone fishes is the most numerous; it includes up to 96% of fish species.
Bony fish include the subclasses Ray-finned and Lobe-finned
CARILY FISH
Class Cartilaginous fish.A relatively small group of fish (about 730 species),whose skeleton remains cartilaginous for life. The body shape is often spindle-shaped.The class is called so because of the presence of a cartilaginous skeleton (Fig. 1), they do not have bone tissue. For example, a shark's jaw, like its skeleton, is also made of cartilage (Fig. 2).
Rice. 1. Cartilaginous skeleton (Source)
Rice. 2. Shark (Source)
The cartilage can be impregnated with calcium salts. Mobile no gill covers instead of them gill slits located on the belly of the fish body or on the sides of the body (Fig. 3).
Rice. 3. An example of the gill slits of a whale shark (Source)
The swim bladder is missing. The skin is bare or covered with scales, which in structure and composition resemble teeth, they are called so - dermal teeth.
The class includes three squads: Sharks, Stingrays, Chimera(fig. 4).
Rice. 4. Units (Source)
Body shape: elongated torpedo body shape.
Length: from 20 cm to 20 m (fig. 5).
Leather: Rough, covered with teeth and scales.
Fins: Paired pelvic and pectoral fins are horizontal, allowing the fish to move up or down. Forward movement and turns are provided by bending the tail or body.
Senses: eyes are located on the sides of the head, vision is black and white. They have a strong sense of smell, feel the slightest vibrations of the water, and so they learn about prey at a great distance.
Fertilization
Some sharks can attack humans. Most sharks are marine fish, but some also swim in fresh waters. One species lives permanently in the freshwater lake of Nicaragua (Fig. 6). Some species of shark are eaten by people, most often the Japanese, liver and fins are considered especially valuable. Leather is used in industry.
Rice. 5. Tiger shark (Source)
Rice. 6. Nicaraguan Freshwater Shark (Source)
Body shape: flattened in the dorsal-abdominal direction.
Fins: Widened pectoral fins on the sides, tail fin shaped like a long, thin whip.
Dimensions (edit): relatively large fish, some reach 6–7 m in width, weight can be in the region of 2.5 tons (Fig. 7). The smallest slopes can be about 12 cm long.
Eyes and mouth: in benthic species, the eyes are located on the upper side of the head, in pelagic species, on the sides. The lateral mouth and gill slits are located on the ventral side of the body.
Leather: Naked or with dermal teeth, mucus secreting glandular cells.
Fertilization: internal, reproduce by viviparity or ovoviviparity.
Representatives of the species lead a benthic lifestyle, large stingrays can live in the water column. Most stingrays are marine, but there are freshwater species as well. Some small freshwater rays are kept in aquariums.
Rice. 7. Skat (Source)
Chimera are a small and distinctive group of deep-sea fish.
Body shape: there is a powerful anterior section and gradually tapers towards the tail.
Length: from 60 cm to 2 m.
Fins: The caudal fin is thin and ends in a thin filamentous appendage.
Leather: naked and devoid of scales.
Fertilization: internal, reproduce by oviposition.
In total, about 30 species of chimera-like fish are known. The most studied European chimera inhabiting the Barents Sea at depths of more than 1000 m (Fig. 8). The Pacific and Atlantic oceans are inhabited by nosed chimeras (Fig. 9).
Rice. 8. European Chimera (Source)
Rice. 9. Nosed Chimera (Source)
BONE FISH
Class Bony fishincludes the overwhelming majority of representatives of the Fishes superclass (about 20 thousand species) inhabiting fresh and salt water bodies.Its name of the class speaks of the presence of a bony skeleton, the body is covered with bone scales or plates, there are no dermal teeth, unlike cartilaginous fish, the gill cavity is covered with gill covers, which are mobile, there is a swim bladder, which can disappear in bottom and sedentary forms (Fig. one).
Rice. 1. Signs of bony fish
It is in bony fish that true lungs appear for the first time in evolution. Fish that have both gills and lungs are called lungs. Most of this once huge group became extinct in the Triassic, but there are several modern groups of lungworms (Fig. 2).
Rice. 2. Australian horntooth
In total, there are about 20 thousand species of bony fish, although this is not often talked about, but bony fish are the most numerous class of vertebrates. The peculiarities of the ecology, structure and physiology of individual species make it possible to divide all this enormous diversity into several dozen groups.
We will discuss only 6 of the most significant of them: Sturgeon-like, Herring-like, Salmon-like, Carp-like, Perch-like, Coelacanth-like.
The sturgeon is a small group that has retained a number of ancient features that emphasize their resemblance to cartilaginous fish. So, in these fish, the notochord is preserved throughout their life, and the skeleton is bone-cartilaginous. The body is elongated, the head begins with a flattened snout (Fig. 3).
Rice. 3. Sturgeon
Representatives of the sturgeon family are found mainly in the temperate latitudes of the Northern Hemisphere. Adult fish spend their entire life in the sea, and enter rivers only for spawning, however, there are completely freshwater forms.
Most sturgeon feeds on aquatic invertebrates, some species feed on small or even large fish.
Meat and especially sturgeon caviar are extremely highly valued as delicacies (Fig. 4). Because of this, sturgeons have always been poached. The construction of hydroelectric power plants has led to the almost complete extinction of sturgeons in many rivers.
The point is that adult fish cannot go up the river through the dam (Fig. 5).
Rice. 4. Black caviar of sturgeon
Rice. 5. Hydroelectric power plant
The order includes fish with an elongated body, slightly compressed from the sides (Fig. 6). Paired and non-paired fins are soft; the lateral line is usually not visible. The body length of the herring is usually 5 to 75 centimeters.
Rice. 6. Herring
Most of the herring are marine fish, however, there are also anadromous species, and some representatives have mastered fresh water bodies too. The most famous of the detachment is the Herring family. These are small and medium sized marine fish. Herring, sardine and sprat are of great commercial importance (Fig. 7).
Rice. 7. Commercial value of herring
Includes fish similar to herring, with a length of 2.5 cm to 1.5 m (Fig. 8). Most members of the salmon family are anadromous fish, but there are freshwater forms as well.
Rice. 8. Salmonids
Often, when entering rivers, salmon have a bright mating outfit (Fig. 9). At this time, salmon do not feed, and only exist thanks to the supply of nutrients accumulated in the sea. After spawning, fish often die.
Rice. 9. Mating dress of salmon
All salmonids are commercial fish highly valued for their delicious meat and caviar. Many salmon are bred in special fish farms. It should be remembered that the diversity of the order Salmonidae is by no means limited to the Salmonidae family (Fig. 10).
Rice. 10. Fishing for salmon
Representatives of this order are very similar to herring, but differ from them in a peculiar structure of the spine. The number of species of this order is about 15 percent of the total diversity of bony fish (Fig. 11).
Rice. 11. Carps
Among carps, there are both herbivorous and omnivorous and even predatory fish. Predatory fish include, for example, piranha and electric eel (Fig. 12).
Rice. 12. Piranha and the Electric Eel
The commercial value of carps is enormous; a number of species are artificially bred in pond farms (Fig. 13).
Rice. 13. Fish farms
The most famous decorative pond fish is the koi carp (Fig. 14). Some tropical carps with beautiful and bright colors have become objects for keeping in aquariums.
Rice. 14. Japanese koi carp
Perchiformes are the most numerous group of fish in terms of species composition. It includes more than 9 thousand species (Fig. 15).
Rice. 15. Perchiformes
Perchiformes are widespread in reservoirs of all continents, in all seas and oceans. Body length - from 1 cm to 5 meters. Weight - from fractions of a gram to a ton or more. For example, a moonfish can be up to 3 meters long and weigh up to one and a half tons (Fig. 16).
Rice. 16. Moonfish
A characteristic feature of the entire order is the presence of 2 dorsal fins with sharp spines. The most famous family of rock perches, perch proper, horse mackerel, catfish, gobies and sailboats.
Obviously, many members of the order are eaten. Small perches are often a favorite of aquarists.
The coelacanths are a very small but very important order of bony fish. In the modern fauna, they are represented by only two species. These last representatives of cross-finned fishes may well be called living fossils (Fig. 17). The fact is that once the first amphibians originated from such fish.
Rice. 17. Celacanthus
Modern lungs
By origin, lungs are a very ancient group of fish that appeared in the Devonian period. Only 2 families with 6 species have survived to this day.
Lungs have both a number of primitive features and a number of features that unite them with amphibians, the most important such feature is, of course, the presence of lungs. The genus Protopter is the best known of the modern lung-breathing species (Fig. 18).
Rice. 18. Protopter
Protopters live in the temporary drying up water bodies of Africa. Remarkable is the ability of these fish, falling into suspended animation and losing a lot of water, to survive the drying out of the reservoir.
Electric eel
A remarkable representative of the carp order is the electric eel, by the way, the electric eel has nothing to do with real eels, it is not a relative of them.
Electric eels live in oxygen-depleted water bodies. Electric eels now have the ability to use oxygen in the air; for this, the fish rises to the surface of the water and captures air through its mouth.
An electric eel is capable of producing a discharge of up to 350 volts, so these fish are protected or hunted by electricity (Fig. 19).
Rice. 19. Electric eel
The amazing story of coelacanth
Fossil remains of coelacanth fish have been known since the Devonian period. After the Cretaceous, no trace of this group was found and it was considered completely extinct.
Rice. 20. Celacanth
And suddenly the fish caught in 1938 turns out to be a real living celacanth (Fig. 20). The discovery of such a living fossil was, of course, a sensation. The fish was named coelacanth. Imagine: a live fish was found, all of whose relatives became extinct back in the era of the dinosaurs.
Fish are vertebrates that live in water bodies and breathe with gills. There are more than 3 thousand species of them in the world. It is believed that it was they who first came out on land, giving rise to land animals. What classes and orders of fish are there? How do they differ from each other? Which order does the moonfish belong to - the heaviest fish in the world? We will answer all these questions in this article.
What makes fish unique?
Fish are an integral part of many ecosystems and important participants in the food chain. They are widespread on the planet, inhabiting salt and fresh water bodies from the oceans to alpine lakes located at an altitude of more than 6 kilometers.
They spend most of their life in water, so the gills are the main respiratory apparatus for them. In many orders of fish there are representatives who are able to briefly crawl to the surface (muddy jumper, climbing perch, some even developed additional respiratory organs - lungs (lung-breathing fish - protopterus, cattle-toothed, etc.).
The almost constant life under water required special adaptations from the fish. Their outer covers are represented by scales - plates of dentin, kosmin or gaonin, which are superimposed on each other like shingles.
They move with the help of fins, and to reduce the body, their body is streamlined. Many fish have. By regulating pressure, it promotes vertical movements of the animal in the water column, and also helps them to stay at a certain depth.
Fish classification
Fish are a group of chordates, within which several classes are distinguished. Their number differs in various sources. Usually they are divided into cartilaginous and bone. Sometimes Bony fishes are distinguished as a superclass, and within it the classes of ray-finned and lobe-finned are distinguished.
The orders of cartilaginous fishes are chimera-like, catran-like, skate-like, sea angels, multigill, llam-like and others. There are about 13 of them in total, and they are represented by various stingrays and chimeras.
The skeleton of these fish is composed of cartilage. In stingrays and sharks, the gills are not covered with a lid, but go out with slits. There is no swim bladder, which forces them to be constantly in motion, otherwise they will fall to the bottom. Some species do not lay eggs, but reproduce by live birth.
The orders of the bony fish class are more numerous. As the name suggests, their skeleton is made of bones. The gills are part of the skeleton, they consist of petals and stamens, and are covered from above with lids.
It is impossible to list all the orders of fish at once in one article, so below we will describe the most interesting or common of them.
Perches
The largest order of fish, which covers about 7-8 thousand species. Most of them are commercial. The main feature of the fish of the order perciformes is the ctenoid scales. Its edges are not even, but are divided into many small teeth. Their pectoral fins are located under the pectorals, and some of the radial fins are turned into spines.
Perchiformes vary greatly in size. Some species reach only a few centimeters (Lucion mystichtis), while others grow up to 3 meters (bluefin tuna). Typical representatives are mackerel, gobies, pike perch, tuna, gourami, swordfish. But sea bass do not belong to them and belong to the order of scorpion-like.
Chimeras
Fish of the order chimera-like have a somewhat bizarre appearance. Their body is elongated and strongly narrowed towards a whip-like tail. A spine is located in front of the two dorsal fins, which can hide in a fold on the back.
The nose is pointed and triangular in shape. In some species, it is strongly elongated, and resembles a proboscis. The mouth is located below. The pectoral fins are large and wing-like in shape.
Chimeras swim slowly, "hovering" in water space. They live at great depths or shelf shallows. They are found in the Indian, Atlantic and Pacific Oceans. They reproduce by laying eggs.
Sturgeon
In terms of structure, sturgeons occupy an intermediate place between the cartilaginous and bony orders of fish. Usually they are classified as bony and cartilage subclass. These include beluga, all kinds of sturgeon, kaluga, sterlet, etc.
Their skeleton consists of cartilage, has a notochord and is not divided into vertebrae. The body of fish is elongated and covered with five rows of large bony plates, between which are located smaller scales. The mouth is located at the bottom. In front of him are four antennae, which play the role of organs of touch.
Sturgeons live in the rivers and seas of the Northern Hemisphere. Fishing for them is very common, caviar is especially appreciated. These are quite large fish. Belugas, for example, reach 4-9 meters, sturgeons - 6 meters.
Blowfish
This order of bony fish includes about 250 species. Most representatives have an unusual body shape: spherical, flattened disc-shaped, cubic, etc. The mouth of the fish is usually small, the bones of the upper jaw are tightly closed. Instead of ordinary scales, their body is covered with thorns or small needles.
They inhabit warm ocean waters near the equator, preferring coral reefs. Notable representatives are the hedgehog fish, the moon fish, the cube box and others. The moonfish is the heaviest fish in the world. Its weight can exceed 20 tons. It has a disc-like shape, flattened from the sides and reaches up to 2 meters in diameter.
Flounders
Flounders are flat fish that swim on their sides. They also lie on their side, so their eyes are placed only on one side. The color, as a rule, is close to the color of the seabed. This is necessary for camouflage, because almost all fish of the order are predators and feed on crustaceans, molluscs and small fish.
They inhabit the seas from tropical to temperate zones, inhabiting mainly near the bottom. Fish prefer shallow waters; individual species easily swim into river mouths. These include flounder, halibut, limanda. The smallest representatives are 7-8 centimeters in size, the largest are about 5 meters.
Herring
Herring is one of the most primitive orders of bony fish. Their body is slightly flattened and covered with semicircular scales. The skull of many fish is made up of cartilage tissue. The fin rays are very soft, which is why the detachment is often called "soft-finned". The detachment includes the Atlantic Menhaden, Baltic herring, Pacific herring, sardine, sprats, anchovy, Baltic herring, sprat.
These fish are very diverse in their way of life; many are capable of making long migrations. They are common in all oceans of the world, especially in tropical regions and subtropical regions. The subpolar regions are inhabited only by certain species, some also live in fresh water bodies. Most are pelagic fish that live in the upper layers of the ocean.
Eels
Unusual representatives of bony fish are the order of eels. Due to their long, elongated body, they can be confused with snakes. However, the body of eels does not taper towards the tail and is often not even flattened laterally.
They wriggle around. The fish have no pelvic fins, exactly like scales. The skin is covered with mucus. Like snakes, they may not have ribs, and the ridge is up to 300 vertebrae. Most eels are venomous and predatory. Particularly large species (giant moray eels) even attack reef and tiger sharks.
They prefer warm water bodies. They are represented by various types of moray eels and eels. The only freshwater family is river eels. They live in water bodies that belong to the basins of the Atlantic, Pacific and Indian Ocean.
Gray sharks
Among all sharks, the most numerous is the order of karcharid or gray sharks. It includes more than 250 species, including hammerhead shark, tiger shark, silk shark, blunt-nosed shark, etc. Its representatives are considered one of the most dangerous inhabitants of the deep sea. On account of them, many human victims.
They live in the coastal zones of the seas of the tropical, subtropical and temperate zones. The fish are constantly moving, then moving away into the depths of the ocean, then swimming in shallow waters. Some species also appear in fresh water bodies.
Gray sharks have five pairs of gill slits, two dorsal and one anal fins. They reproduce either by laying eggs or by live birth.
They have a large mouth located below, and the snout is extended forward. In some sharks, it is strongly rounded (in blunt sharks). The hammerhead shark has a specific look. Their muzzle is flattened at the top and wide at the sides, reminiscent of the leading edge of a hammer. The first dorsal fin is curved in the shape of a sickle.
