Names of fish fins. §31. Pisces: general characteristics and external structure. General description of the family
Cartilaginous fish .
Paired fins: The shoulder girdle looks like a cartilaginous semi-ring lying in the muscles of the body walls behind the branchial region. On its lateral surface there are articular processes on each side. The part of the belt lying dorsal to this process is called scapular section, more ventral – coracoid region. At the base of the skeleton of the free limb (pectoral fin) there are three flattened basal cartilages, attached to the articular process of the shoulder girdle. Distal to the basal cartilages are three rows of rod-shaped radial cartilages. The rest of the free fin is his cutaneous lobe– supported by numerous thin elastin threads.
Pelvic girdle It is represented by a transversely elongated cartilaginous plate lying in the thickness of the abdominal muscles in front of the cloacal fissure. The skeleton of the ventral fins is attached to its ends. IN ventral fins there is only one basal element. It is greatly elongated and one row of radial cartilages is attached to it. The rest of the free fin is supported by elastin threads. In males, the elongated basal element continues beyond the fin blade as the skeletal basis of the copulatory outgrowth.
Unpaired fins: Typically represented by a caudal, anal, and two dorsal fins. The tail fin of sharks is heterocercal, i.e. its upper lobe is significantly longer than the lower one. The axial skeleton, the spine, enters it. The skeletal base of the caudal fin is formed by elongated upper and lower vertebral arches and a number of radial cartilages attached to the upper arches of the caudal vertebrae. Most of The tail blades are supported by elastin threads. At the base of the skeleton of the dorsal and anal fins lie radial cartilages, which are embedded in the thickness of the muscles. The free blade of the fin is supported by elastin threads.
Bony fish.
Paired fins. Represented by pectoral and ventral fins. The shoulder girdle serves as support for the pectorals. The pectoral fin at its base has one row of small bones - radials, extending from the scapula (component of the shoulder girdle). The skeleton of the entire free fin blade consists of articulated skin rays. The difference from cartilaginous ones is the reduction of basalia. The mobility of the fins is increased, since the muscles are attached to the expanded bases of the skin rays, which movably articulate with the radials. The pelvic girdle is represented by paired flat triangular bones closely interlocking with each other, lying in the thickness of the muscles and not connected with the axial skeleton. Most teleost pelvic fins lack basalia in the skeleton and have reduced radials - the blade is supported only by cutaneous rays, the expanded bases of which are directly attached to the pelvic girdle.
Unpaired limbs. They are represented by dorsal, anal (subcaudal) and caudal fins. Anal and dorsal fins consist of bone rays, divided into internal (hidden in the thickness of the muscles) pterygiophores(corresponding to radials) and external fin rays - lepidotrichia. Caudal fin asymmetrical. It is a continuation of the spine - urostyle, and behind and below it there are flat triangular bones like a fan - hypuralia, derivatives of the lower arches of underdeveloped vertebrae. This type of fin structure is externally symmetrical, but not internally - homocercal. The external skeleton of the caudal fin is composed of numerous cutaneous rays - lepidotrichia.
There is a difference in the location of the fins in space - in cartilaginous horizontally to maintain in water, and in teleosts vertically, since they have a swim bladder. Fins perform various functions when moving:
- unpaired - dorsal, caudal and anal fins, located in the same plane, help the movement of the fish;
- The paired pectoral and pelvic fins maintain balance and also serve as a rudder and brake.
TOPIC 1.
Fish fins Organi dikhannya, zora ta rasmu.
FISH FINS
The fins are characteristic feature structure of fish. They are divided into paired, corresponding to the limbs of higher vertebrates, and unpaired, or vertical.
Paired fins include pectoral and ventral fins. Unpaired ones consist of a dorsal (one to three), caudal and anal (one or two). Salmon, grayling and other fish have an adipose fin on their back, and mackerel, tuna, and saury have small additional fins behind the dorsal and anal fins. The position of the fins on the body, their shape, size, structure and functions are very diverse. Fish use fins to move, maneuver and maintain balance. In most fish, the caudal fin plays the main role in moving forward. It performs the work of the most advanced propeller with rotating blades and stabilizes the movement. The dorsal and anal fins are a kind of keels for giving the fish’s body the desired stable position.
Two sets of paired fins serve for balance, braking and steering.
The pectoral fins are usually located behind the gill openings. The shape of the pectoral fins is related to the shape of the caudal fins: they are rounded in fish that have a rounded tail. Good swimmers pectoral fins pointed. The pectoral fins of flying fish are especially strongly developed. Thanks to high speed movement and blows of the caudal fin, flying fish jump out of the water and soar on wing-shaped pectoral fins, covering a distance of up to 100-150 m in the air. Such flights help them hide from the pursuit of predators.
The pectoral fins of the monkfish have a segmented, fleshy base. Relying on them angler moves along the bottom in leaps and bounds, as if on legs.
Location of the pelvic fins different fish not the same. In lowly organized fish (sharks, herring, carp) they are located on the belly. In more highly organized fish, the ventral fins move forward, occupying a position under the pectoral fins (perch, mackerel, mullet). In cod fish, the pelvic fins are located in front of the pectoral fins.
In gobies, the pelvic fins are fused into a funnel-shaped sucker.
The pelvic fins of the lumpfish have changed into an even more amazing adaptation. Their suction cup holds the fish so firmly that it is difficult to tear it off the stone.
From unpaired fins Special attention deserves a tail, complete absence which is observed very rarely (stingrays). Based on the shape and location relative to the end of the spine, several types of caudal fins are distinguished: asymmetrical (heterocercal) - in sharks, sturgeons, etc.; false symmetrical (homocercal) - in the majority bony fish.
The shape of the caudal fin is closely related to the fish's lifestyle and especially its ability to swim. Good swimmers are fish with lunate, fork-shaped and notched tails. Less mobile fish have a truncated, rounded caudal fin. In sailboats it is very large (up to 1.5 m long), they use it as a sail, placing it above the surface of the water. In spiny-finned fish, the rays of the dorsal fin are strong spines, often equipped with poisonous glands.
A peculiar transformation is observed in the sticky fish. Its dorsal fin moves to its head and turns into a suction disk, with the help of which it attaches to sharks, whales, and ships. In angler fish, the dorsal fin moves to the snout and extends into a long thread that serves as a bait for prey.
Fins organs of movement of aquatic animals. Among invertebrates, P. have pelagic forms of gastropods and cephalopods and setaceous-maxillary. U gastropods P. are a modified leg; in cephalopods, they are lateral folds of skin. The chaetomagnaths are characterized by lateral and caudal wings formed by folds of skin. Among modern vertebrates, cyclostomes, fish, some amphibians, and mammals have P. In cyclostomes there are only unpaired P.: anterior and posterior dorsal (in lampreys) and caudal. In fish, there are paired and unpaired P. Paired ones are represented by anterior (thoracic) and posterior (abdominal) ones. In some fish, such as cod and blennies, abdominal P. are sometimes located in front of the thoracic ones. The skeleton of paired limbs consists of cartilaginous or bone rays, which are attached to the skeleton of the limb girdles (See Limb girdles) ( rice. 1
). The main function of paired propellers is the direction of fish movement in the vertical plane (depth rudders). In a number of fish, paired parasites perform the functions of active swimming organs (See Swimming) or are used for gliding in the air (in flying fish), crawling along the bottom, or moving on land (in fish that periodically leave the water, for example, in representatives of the tropical genus Periophthalmus , which, with the help of chest pectorals, can even climb trees). The skeleton of unpaired P. - dorsal (often divided into 2 and sometimes into 3 parts), anus (sometimes divided into 2 parts) and caudal - consists of cartilaginous or bone rays lying between the lateral muscles of the body ( rice. 2
). The skeletal rays of the caudal vertebrae are connected to the posterior end of the spine (in some fish they are replaced by the spinous processes of the vertebrae). The peripheral parts of the P. are supported by thin rays of horn-like or bone tissue. In spiny-finned fish, the anterior of these rays thicken and form hard spines, sometimes associated with poisonous glands. Muscles that stretch the lobe of the pancreas are attached to the base of these rays. The dorsal and anal parasites serve to regulate the direction of movement of the fish, but sometimes they can also be organs forward movement or perform additional functions (for example, attracting prey). The caudal part, which varies greatly in shape in different fish, is the main organ of movement. During the evolution of vertebrates, P. fishes probably arose from a continuous skin fold, which ran along the back of the animal, went around the rear end of its body and continued on the ventral side to the anus, then divided into two lateral folds that continued to the gill slits; This is the position of the fin folds in the modern primitive chordate - Lancelet a. It can be assumed that during the evolution of animals, skeletal elements formed in some places of such folds and in the intervals the folds disappeared, which led to the emergence of unpaired folds in cyclostomes and fish, and paired ones in fish. This is supported by the presence of lateral folds or venom of spines in the most ancient vertebrates (some jawless, acanthodia) and the fact that in modern fish paired P. have a greater extent of early stages development than in adulthood. Among amphibians, unpaired amphibians, in the form of a fold of skin devoid of a skeleton, are present as permanent or temporary formations in most larvae living in water, as well as in adult caudate amphibians and the larvae of tailless amphibians. Among mammals, P. are found in cetaceans and lilacs that have switched to an aquatic lifestyle for the second time. Gypsy cetaceans (vertical dorsal and horizontal caudal) and lilacs (horizontal caudal) do not have a skeleton; these are secondary formations that are not homologous (see Homology) to the unpaired P. of fish. The paired limbs of cetaceans and lilacs, represented only by the anterior limbs (the hind limbs are reduced), have an internal skeleton and are homologous to the forelimbs of all other vertebrates. Lit. Guide to Zoology, vol. 2, M.-L., 1940; Shmalgauzen I.I., Fundamentals of comparative anatomy of vertebrate animals, 4th ed., M., 1947; Suvorov E.K., Fundamentals of Ichthyology, 2nd ed., M., 1947; Dogel V.A., Zoology of invertebrates, 5th ed., M., 1959; Aleev Yu. G., Functional principles of the external structure of fish, M., 1963. V. N. Nikitin.
Big Soviet encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
See what “Fins” are in other dictionaries:
- (pterigiae, pinnae), organs of movement or regulation of body position of aquatic animals. Among invertebrates, pelagics have P. forms of certain mollusks (modified leg or fold of skin), bristle-jawed. In skullless fish and larvae of fish, the unpaired P.... ... Biological encyclopedic dictionary
Organs of movement or regulation of body position of aquatic animals (some mollusks, chaetognaths, lancelets, cyclostomes, fish, some amphibians and mammals, cetaceans and sirenids). They can be paired or unpaired. * * * FINS… … encyclopedic Dictionary
Organs of movement or regulation of body position of aquatic animals (some mollusks, chaetognaths, lancelets, cyclostomes, fish, some amphibians and mammals, cetaceans and sirenids). There are paired and unpaired fins … Big Encyclopedic Dictionary
Task 1. Complete laboratory work.
Subject: "External structure and features of fish movement."
Goal of the work: study the features of the external structure and methods of movement of fish.
1. Make sure that the workplace has everything necessary to perform laboratory work.
2. Using the instructions given in paragraph 31 of the textbook, perform laboratory work, filling out the table as you observe.
3. Sketch appearance fish. Label the body parts.
4. Write down the results of your observations and draw conclusions. Note the features of fish adaptation to aquatic environment.
Fish are well adapted to life in the aquatic environment. They have a streamlined body shape, fins, and sensory organs that allow them to navigate in the water.
Task 2. Fill out the table.
Task 3. Write down the numbers of the correct statements.
Statements:
1. All fish have a streamlined body shape.
2. The body of most fish is covered with bony scales.
3. The skin of fish has cutaneous glands that secrete mucus.
4. The head of the fish imperceptibly passes into the body, and the body into the tail.
5. The tail of a fish is that part of the body that is bordered by the caudal fin.
6. There is one dorsal fin on the dorsal side of the fish’s body.
7. The fish uses its pectoral fins as oars when moving.
8. Fish eyes do not have eyelids.
9. Pisces see objects located at close distances.
Correct statements: 1, 2, 3, 4, 5, 6, 8, 9.
Task 4. Fill out the table.
Task 5. The body shape of fish is very diverse: bream have a high body and strongly compressed laterally; in flounder - flattened in the dorso-ventral direction; in sharks it is torpedo-shaped. Explain what causes the differences in body shapes in fish.
Because of habitat and movement.
Flounder have a flattened shape because they swim slowly along the bottom.
The shark, on the contrary, moves quickly (the tarpedoid shape ensures fast movement in open water).
The bream's body is flattened laterally because it moves in bodies of water with dense vegetation.
; their organs that regulate movement and position in water, and in some ( flying fish) - also planning in the air.
The fins are cartilaginous or bony rays (radials) with skin-epidermal coverings on top.
The main types of fish fins are dorsal, anal, caudal, pair of abdominal and pair of pectoral.
Some fish also have adipose fins(they lack fin rays), located between the dorsal and caudal fins.
The fins are driven by muscles.
Often, different species of fish have modified fins, for example, males viviparous fish use the anal fin as an organ for mating (the main function of the anal fin is similar to the function of the dorsal fin - it is a keel when the fish moves); at gourami modified thread-like ventral fins are special tentacles; highly developed pectoral fins allow some fish to jump out of the water.
The fins of fish actively participate in movement, balancing the body of the fish in the water. In this case, the motor moment begins from the caudal fin, which pushes forward with a sharp movement. The tail fin is a kind of propulsion device for the fish. The dorsal and anal fins balance the fish's body in the water.
Different species of fish have different numbers of dorsal fins.
Herring and carp-like have one dorsal fin mullet-like and perch-like- two, y codlike- three.
They can also be located differently: pike- displaced far back, at herring-like, carp-like- in the middle of the ridge, at perch and cod- closer to the head. U mackerel, tuna and saury there are small additional fins behind the dorsal and anal fins.
The pectoral fins are used by the fish when swimming slowly, and together with the pelvic and caudal fins they maintain the balance of the fish’s body in the water. Many bottom-dwelling fish move along the ground using pectoral fins.
However, in some fish ( moray eels, for example) pectoral and ventral fins are absent. Some species also lack a tail: gymnots, ramfichtids, seahorses, stingrays, sunfish and other species.
Three-spined stickleback
In general, the more developed a fish's fins, the more suited it is to swimming in calm water.
In addition to movement in water, air, on the ground; jumps, jumps, fins help different types fish attach to the substrate (suction fins on bulls), look for food ( triggles), have protective functions (sticklebacks).
Some types of fish ( scorpionfish) have poisonous glands at the base of the spines of the dorsal fin. There are also fish without fins at all: cyclostomes.
