Characteristics of animals of the chordate type. Chordata

1. Deuterostomes, secondary body cavity (whole)

2. The circulatory system is closed, the blood is oxidized in specialized respiratory organs (gills or lungs)

3. Body with bilateral symmetry

4. The body, to one degree or another, consists of metamers

5. A notochord runs along the entire body; in some, it is present only at the larval or embryonic stage of development

6. Higher animals have a cartilaginous or bony skeleton

7. The pharynx is penetrated by gill slits in many people only at the embryonic stage of development

8. Central nervous system in the form of a tube, located above the chord

Classification

chordates

skullless

TUNICATA (UROCHORDATA)

CRANIOTA (VERTEBRATA)

cranial (vertebrate)

skullless

cephalochordates

lanceolate

Branchiostomidae Epigonichtidae Amphioxididae

Families:

tunicates (larval chordates)

TUNICATA (UROCHORDATA)

appendiculars

cranial (vertebrate)

CRANIOTA (VERTEBRATA)

jawless

gnathostomes

(and modern lampreys)

extinct scutes

Pteraspidomorphi

(extinct)

Cephalaspidomorphi

(extinct)

armored fish

(extinct)

maxillobranchs

(extinct)

cartilaginous fish

bony fish

amphibians

parareptiles

reptiles

mammal

topic: General characteristics of skullless

The lancelet is a representative of the skullless, most primitive chordate animals. All the main characteristics of the chordate type in skullless animals are well expressed and preserved for life. The notochord functions as an axial skeleton, the central nervous system is represented by the neural tube, and the pharynx is penetrated by gill slits.

There is a secondary mouth and a secondary body cavity - the whole. Metamerism persists in a number of organs. Skullless animals are characterized by bilateral (bilateral) body symmetry. These characters indicate a phylogenetic connection between skullless animals and certain groups of invertebrate animals (annelides, echinoderms, etc.).

In addition, skullless animals, and in particular the lancelet, are characterized by a number of specific primitive features that distinguish them well from other chordates. These differences are as follows.

The epidermis is single-layered, covered with a thin cuticle. Cutis is poorly expressed and is represented by a thin layer of gelatinous tissue. The central nervous system is not differentiated into the brain and spinal cord. Due to the absence of a brain, there is no skull.

The sense organs are poorly developed: there are only tactile cells with sensitive hairs (these cells are scattered over the surface of the body) and light-sensitive formations - the eyes of Hesse, located in the walls of the neural tube.

The gill slits do not open outward, but into the atrial, or peribranchial, cavity, which arises as a result of the fusion of the lateral (metapleural) folds of the skin. The digestive system consists of a poorly differentiated tube, in which only two sections are distinguished: the pharynx and the intestine.

At the bottom of the pharynx there is a longitudinal groove - endostyle lined ciliated epithelium and glandular cells. At the oral opening, the endostyle bifurcates and, bending around it on both sides with two grooves, rises to the upper side of the pharynx, where it passes into the epibranchial groove directed towards the intestine. The function of the endostyle is to extract food particles from the water. The latter, entering the pharyngeal section of the intestine along with the flow of water, settle to the bottom of the pharynx, are enveloped in mucus, which is secreted by the glandular cells of the endostyle, and are driven forward by the ciliated epithelium to the oral opening. Here, lumps of food rise along the perioral grooves to the epibranchial groove and are transported along it to the intestine.

The lancelet's blood is colorless and there is no heart.

The excretory organs are represented by metamerically arranged nephridia - short tubes, which in the number of 90 pairs are located above the pharynx. Each tube opens at one end with several openings - nephrostomes as a whole, and at the other - with one opening into the atrial cavity. Nephrostomes are covered with special club-shaped cells - solenocytes, inside of which there is a tubule with a ciliated hair included in it. Excretion products are excreted through the nephridia into the atrial cavity directly from the coelom.

The reproductive organs - testes and ovaries are similar in external structure and are round bodies. They are located in the gill section of the shell. Reproductive products are excreted into the atrial cavity through temporarily emerging pelvic ducts.

Skullless are exclusively marine animals. They spend most of their time buried in the sandy bottom soil. They feed passively, extracting food particles from the water, which is driven by the movement of the tentacles through the animal’s throat.

A similar lifestyle is ensured in modern skullless animals by a number of morphological adaptations. The epithelium contains special unicellular glands that secrete mucus, which protects the integument of the lancelet from mechanical damage when buried in the ground. Successful burying in the ground is facilitated by relatively large muscles and the lancet-shaped shape of the tail. The above-mentioned atrial cavity protects the respiratory apparatus from clogging with soil particles. Numerous gills the cracks ensure the passage of a large amount of water through them, which is necessary for the breathing of an animal half-buried in the sand. The presence of an endostyle in the pharynx and the initial movement of mucus along it towards the flow of water help to more quickly and completely remove the beggar from it, which is very important with a passive method of feeding.

Topic: Characteristics of cyclostomes

The elongated acne-like body is covered with smooth mucous skin and has only unpaired fins(supported by cartilaginous rays). The skeleton has no ribs or skeleton of limbs; the skeleton of the head consists of a cartilaginous, membranous box on top that covers the brain and associated capsules surrounding the organs of hearing, vision and smell, cartilage that supports the mouth and palate and a ethmoid box that covers the gill apparatus (the back part of it surrounds the heart).

The skeleton of the body consists of a dorsal string (Chorda dorsalis), covered with a double elastic membrane and an external layer connective tissue(skeletal layer); in which on the upper side paired cartilages develop, corresponding to the vertebral arches, and unpaired, corresponding to the spinous processes; in the area of the tail, the same cartilages are found on the underside of the notochord.

The brain is poorly developed, there are no large sympathetic trunks, the sense organs are of an extremely primitive structure (the eyes of some are hidden under the skin in the larval period or throughout life, the nasal cavity of hagfishes opens into the mouth).

The round, funnel-shaped mouth is armed with horny teeth; the same teeth are found on the tongue, which plays the role of a piston when sucking on underwater objects (or the body of prey). The branchial apparatus consists of 6-7 gill cavities lying on the sides of the esophagus and communicating with the esophagus on one side and with the external environment on the other. Unlike all other fish, in which water enters through the mouth and exits through the gill slits during respiration, here water enters and exits independently of the mouth opening, which allows these animals to breathe while they suck with the mouth.

The intestine has a spiral fold of mucous membrane.

The circulatory organs are arranged according to the same type as those of other fish (see); the heart consists of 1 atrium (preceded by the sinus venosus) and 1 ventricle (followed by the conus arteriosus with 2 valves).

The excretory organs - the kidneys - are of a very primitive structure. The genitals are in the form of an unpaired gland in hagfishes on the right side of the body cavity, in lampreys along the midline.

Mature reproductive products fall into the body cavity, from where they are excreted through a special opening into the urogenital sinus, which lies behind the anus. In hagfishes, according to some studies (Nansen et al.), in the gonad, male reproductive products (semen) develop first in the posterior half of the gland, and then eggs in the anterior part of the gland. Eggs undergo complete crushing; in some, development is associated with transformations (in lampreys). 2 families with 6 genera and 17 species.

Family lamprey(Petromyzontidae) is distinguished by the following characteristics: a mouth with fleshy lips, without thread-like appendages (whiskers) at the edge, the nasal cavity does not communicate with the oral cavity, the gills open outward with seven holes on each side, and into the esophagus with one common hole; eyes are clear; 4 genera with 12 species. Found in rivers and seas off the coast of temperate zones, some species enter rivers from the sea to spawn. They feed on the meat and blood of fish (live or corpses), to which they attach, as well as various small invertebrates. From the small eggs of lampreys, worm-like larvae emerge with a toothless mouth opening, equipped with upper and lower lips, eyes hidden under the skin, and a dorsal fin that directly turns into a caudal fin. The gill sacs open into the esophagus with separate openings. They live in sand and silt, feed on various animal substances and gradually transform into an adult animal. The only one European genus lamprey (Petromyzon) with 2 dorsal fins, of which the hind fin goes into the caudal fin, and numerous small short projections along the edge of the mouth; tongue with saw-toothed teeth, on the upper side of the mouth (in place of the upper jaw) 2 adjacent teeth or a transverse plate. Found in the northern temperate zone.

sea lamprey(P. marinus) reaches a length of 1 m and a weight of more than 1.5 kg (up to 3). There is a large gap between the dorsal fins; see the fig. for features of the oral armament; the color is yellowish-white or gray, with a black-brown or olive-green pattern on the back and sides. It is found off the coast of Europe, North America and western Africa, and is also found in the Baltic Sea. Enters rivers to spawn; meat is valuable.

Topic: Characteristics of cartilaginous fish

In elasmobranch fish, which include sharks and rays, bone tissue is completely absent. They have a cartilaginous skeleton, which is often calcified. The upper jaw is represented by a massive palatoquadrate cartilage, which does not merge with the cranium and is connected to it only by connective tissue ligaments or cartilage joints. The skin of elasmobranchs is usually covered with placoid scales, which are the most ancient type of scale cover. Each such scale consists of a main plate on which rises a conical or mushroom-shaped tooth (skin tooth), covered with a layer of enamel and ending in one or more points. The presence of dermal teeth gives the skin of sharks a more or less pronounced and sometimes very strong roughness, thanks to which it can be used in carpentry as an abrasive material. Modified skin teeth form fin spines in horned and spiny sharks, tail spines in stingrays, sawtooth teeth on the snout (rostrum) in sawfish and sawfish. Jaw teeth, made of dentin and covered with enamel on the outside, are also a modification of placoid scales. The shape of teeth in elasmobranchs can be very diverse. They can be flat triangular or pointed conical, tuberculate or awl-shaped, smooth or jagged, single-peaked or with additional tips. The teeth are located on the jaws in straight and oblique rows, and in each straight row (from the edge of the jaw to its inner part) there are teeth of several generations. Usually only the front row (sometimes several front rows) functions; the remaining teeth are bent inward and replace the front ones as they wear out.

Elasmobranch fish never have an operculum, and on each side of the body 5–7 gill slits open outward. Many fish also have squirts - small holes located behind the eye and representing the rudiment of another gap between the jaw and hyoid arches. The gill filaments of sharks are plate-shaped and attached to arches along their entire length (hence the name “elasmobranch fish”). The presence of a spiral valve in the intestine and a conus arteriosus in the heart are important anatomical features of elasmobranchs. The spiral valve is an outgrowth of the mucous membrane of the digestive tract. It forms from 4 to 50 revolutions and greatly increases the absorption surface of the intestine. The conus arteriosus is a special section of the heart located in front of the ventricle and equipped with several rows of semilunar valves. It is capable of independent rhythmic contractions. Osmotic pressure internal environment in elasmobranch fish it is provided mainly by urea dissolved in the blood. In this case, there is hypertension of the cavity fluids in relation to the external environment. Due to this feature, fresh shark meat, as a rule, does not have a particularly pleasant specific odor, which disappears with appropriate cooking.

The reproduction process of elasmobranchs is characterized by specific features. Fertilization occurs inside the female's body, and males therefore have two copulatory organs called pterygopodia. With their help, sperm is introduced into the female's cloaca. The pterygopodium is a modified posterior part of the ventral fin and has an external groove. The fertility of elasmobranchs is low, but their eggs have very large reserves of nutrients. Reproduction occurs by oviparity, ovoviviparity, or viviparity. In oviparous species, the fertilized egg, descending through the oviduct, passes through the albumen and shell glands and is covered with membranes that form a hard shell. The egg is then laid on the bottom. Ovoviviparous species, to which most modern sharks belong, are characterized by the fact that the fertilized egg remains in the posterior part of the oviducts (in the “uterus”) until the birth of the young. At the same time, in some stingrays, a kind of feeding of developing embryos takes place: the walls of the “uterus” form outgrowths that penetrate into the oral cavity of the embryos and secrete a nutritious fluid somewhat reminiscent of milk. Finally, in viviparous sharks, in which the development of the embryo also occurs in the “uterus,” there is even a semblance of a child’s place (placenta), which serves to nourish the embryo from the mother’s blood. In any case, newborn shark-like fish are born fully prepared for independent existence. The body shape of elasmobranch fishes is very diverse. Some of them have a torpedo-shaped body, adapted for rapid movement, and are good swimmers, others are flattened in the dorso-ventral direction, and usually spend their lives lying on the bottom. Their sizes vary greatly: the smallest species do not exceed 15-30 cm in length, while basking sharks and stingrays reach a length of 15-20 m, and the weight is measured in tons.

The first elasmobranch fish appeared in ancient seas 300 million years ago, starting in the mid-Devonian period. Modern elasmobranchs arose later, but many of the living families have existed since Jurassic period, i.e. at least 150 million years. However, sharks still successfully compete with bony fish without showing any signs of extinction. The classification of modern elasmobranchs, of which there are now about 600 species, is based mainly on the characteristics external structure and some features of anatomy. Usually two large groups are distinguished - the superorder of sharks (Selachomorpha) and the superorder of rays (Batomorpha). Elasmobranchs are a predominantly marine group of fish that flourishes most in tropical waters. Their commercial importance is relatively small, although they are mined in many areas. The total catch of elasmobranchs (sharks and rays) now reaches about 1% of the total annual catch of marine fish.

Topic: Characteristics of bony fish

Bony fish, like cartilaginous fish, have paired limbs - fins, the mouth is formed by grasping jaws with teeth on them, gills are located on gill arches with internal skeletal support, paired nostrils, and there are three semicircular canals in the inner ear. Unlike cartilaginous fish, the skeleton of bony fish contains bone tissue, and a swim bladder is located in the upper part of the body cavity; the gill cavity is covered by an operculum reinforced by a bone skeleton; the gills have the shape of freely hanging petals, rather than plates adhered to the interbranchial septa. The body is covered with bony scales, plates, or bare instead of a covering of tooth-like placoid scales.

Among bony fishes there are giants and dwarfs - from freshwater beluga, kaluga, catfish, reaching 5-7 m in length and 500-1500 kg in weight, Brazilian arapama and sea swordfish and marlins to tiny Philippine gobies, 7-11 mm in length .

On the sides of the body and on the head, pores of the lateral line are usually visible - a special organ, characteristic only of aquatic animals, for the sense of perception of water movements. Thanks to the lateral line, even blinded fish do not bump into obstacles and are able to catch moving prey.

The fish's mouth is usually armed with teeth; teeth are found not only on the jaws, but often also on the palatine bones, on the vomer, on the tongue, and on the bones of the gill apparatus (pharyngeal teeth). The sides of the pharynx are strengthened by five pairs of bony gill arches, along inner edge of which there are hard gill rakers, and along the outer edge there are gill petals abundantly supplied with blood. Through 4 pairs of slits between the gill arches, the fish actively passes water, filtering it through the lattices of gill rakers and gill filaments. With the help of the former, crustaceans and other organisms that serve as food for fish are retained in the pharyngeal cavity and enter the esophagus, while in the gill filaments the oxidation of passing blood occurs by extracting oxygen dissolved in it from the water that washes them. Gills serve as the respiratory organ of fish. The intestine is usually relatively poorly differentiated into sections: blind outgrowths are specific to fish - pyloric appendages (from 1 to 200), opening at the beginning of the midgut, immediately behind the stomach; Primitive fish, such as sturgeons, have a spiral fold in the large intestine, like sharks and rays. Adjacent to the intestine is a lobed liver equipped with a gall bladder. The pancreas is usually poorly isolated: its small lobules (islands) are adjacent to the stomach or interspersed in the liver. It produces insulin, and it is possible to use it as a raw material for the production of this valuable medicinal drug. The heart is located in the front of the body cavity - in the area corresponding to the throat of the fish. It consists of an atrium and a ventricle, and only venous blood passes through it, pumped by the heart into the gills. From there, after being enriched with oxygen in the gill filaments, the blood flows to various organs of the body. Fish have a two-chambered heart and only one circulation. Only in lungfishes, due to the presence of lungs, circulatory system more difficult. The kidneys of fish look like dark red ribbons, located immediately under the spine and extending along the entire dorsal edge of the body cavity. Between them and the intestines there is a swim bladder, which in fish carries the functions of a hydrostatic apparatus, as well as an organ regulating gas exchange and, in some fish, - function sound resonator. The sac-shaped ovaries (or ovaries) in females and the lobed, whitish testes (or ovaries) in males have excretory canals that open outward on the urogenital or special genital papilla, behind the anus. The brain of fish is usually very small and has a very primitive structure: the forebrain cortex, which serves as an associative center in higher vertebrates, is completely undeveloped in bony fish, unlike sharks, in which it consists of brain tissue. The centers of various senses are isolated in different parts of the brain: smell - in the forebrain, vision - in the middle, hearing and touch - in the medulla oblongata, the center for coordination of movements - in the cerebellum. The relative size of these sections corresponds to the role of the fish's various senses, and appearance brain allows you to judge your lifestyle. Of particular importance is the lower cerebral appendage - the pituitary gland, which looks like a small bulb sitting on the lower surface of the brain, behind the crossing of the optic nerves. Injecting pituitary gland extract into maturing female fish greatly accelerates the ripening of eggs and is used for this purpose in industrial fish farming.

Topic: Characteristics of amphibians

Amphibians, or amphibians, are the first, relatively small group of primitive terrestrial vertebrates. However, they still maintain a close connection with the aquatic environment. This is most fully manifested during the period of embryonic and postembryonic development. The laying of caviar (eggs) and its development in the vast majority of amphibians occurs in water.

The larvae emerging from the eggs - tadpoles - also live in aquatic environment. They have the characteristics of typical aquatic animals: gill breathing, two-chambered heart, one circle of blood circulation, lateral line organs. After metamorphosis, amphibians acquire the characteristics of typical terrestrial vertebrates.

Adult amphibians are characterized by pulmonary breathing. The circulatory system changes accordingly: the heart becomes three-chambered, a pulmonary circulation appears, the branchial arteries are replaced by homologous carotid arteries, systemic arches and the aorta and pulmonary arteries. The posterior vena cava, characteristic of terrestrial vertebrates, appears. The sense organs are noticeably improved: the shape of the cornea of the eye becomes convex, the lens becomes lenticular, movable eyelids and the middle ear cavity with the eardrum and auditory bone - the stirrup - appear. The digestive tract is much more differentiated than in fish. Ground limbs of the five-fingered type appear. The limb girdles become more complex. There is a strong articulation of the hind limb girdle with the axial skeleton, etc.

However, despite these transformations, amphibians are still poorly adapted to living on land. This is reflected in poor development of the lungs, and therefore bare skin plays an important role in the breathing process. The skin, which is easily permeable to gases and water, does not protect the body from drying out, which necessitates the need to constantly replenish water losses. The three-chambered heart does not provide complete separation of blood, and more or less mixed blood is distributed throughout the body. The limbs are still poorly developed and cannot hold the body in an elevated position above the ground. Moche reproductive system in almost all amphibians it is not fundamentally different from that of fish. Amphibians, like fish, are characterized by poikilothermy (inconstancy of body temperature).

The skeleton of a typical representative of the amphibian class, the frog, is characterized by a combination of progressive features characteristic of terrestrial vertebrates with a number of adaptive features.

The first can be named: free limbs of the five-fingered type, the formation of girdles and limbs from three homodynamic elements (constructed according to a single scheme), the connection of the pelvic girdle with the axial skeleton, autostyly, i.e. fusion of the palatoquadrate cartilage with the cranium, transformation of the hyoid arch , reduction of the gill covers and parts of the gill arches, greater differentiation of the spine.

Features of specialization in the frog skeleton are manifested in slight ossification of the skull, weak development of the cervical and sacral spine, absence of ribs, replacement of the caudal vertebrae with a single bone - the urostyle, elongation of the iliac bones and significant deviations of the skeleton of the free limbs from the typical five-fingered limbs of terrestrial vertebrates. However, in other groups of amphibians (tailed and legless) not all of the listed adaptive characteristics are found.

Topic: Characteristics of reptiles

Reptiles are the first class of higher terrestrial vertebrates. They differ from amphibians in a number of progressive features and adaptation to a terrestrial lifestyle. Special attention deserves a more complex structure of the central nervous system - the brain and sensory organs - than that of amphibians.

In the reptile brain, the forebrain hemispheres are much more developed. The gray medulla forms the superficial layer, the true cerebral cortex - the secondary medullary vault.

Among the progressive features of reptiles, the development of the skeleton as a whole should be noted. The appearance of a true rib cage provides stronger support for the forelimbs. Strengthening the pelvic girdle by attaching it to the transverse processes of two (and not one, as in amphibians) sacral vertebrae helps to strengthen the support on the hind limbs.

In reptiles, the calcaneal joint is not located between the lower leg and foot, as in amphibians, but between two rows of tarsal bones. In this way, the so-called intertarsal (intertarsal) joint is formed, which is very characteristic of many reptiles and all birds.

The massive bony skull articulates with the spine with a single condyle. The separation of the neck, as well as the formation of the special structure of the first two cervical vertebrae - the atlas and epistrophea - provides greater mobility of the head.

Breathing in reptiles is exclusively pulmonary. The well-drained trachea is divided into two bronchi that enter the lungs. The lungs have a more complex structure than those of amphibians; they are characterized by internal complex septa that reduce the overall cavity of the lung. The degree of development of these partitions varies among different groups of reptiles. In lizards and snakes they are poorly developed; in turtles and crocodiles the lungs are already massive spongy organs.

The circulatory system of reptiles is also more advanced compared to that of amphibians. Most reptiles have a three-chambered heart and, in addition, an incomplete septum develops in the ventricle (crocodiles have a four-chambered heart). The arterial trunk breaks up into three vessels, which branch independently from various parts of the ventricle.

An essential aspect of the higher organization of reptiles is the development of the pelvic kidneys (metanephros).

The most important adaptive features of reptiles for life on land are exclusively internal fertilization, an increase in the size of eggs and the appearance of embryonic membranes.

A large egg, usually covered with dense shells, with a significant supply of yolk ensures the development of the embryo outside of water and without larval stages. During the development of the embryo, a system of embryonic membranes appears, of which the amniotic membrane, or amnion, served as the basis for uniting higher vertebrates into the group of amniotes.

The skin of reptiles has important adaptive significance. Horny formations are formed in it - scales, scutes, which make up the outer cover that protects the body from drying out. There are almost no glands in the skin of reptiles.

A characteristic feature of reptiles is periodic molting, during which the old stratum corneum of the skin is replaced by a new one.

The skeleton of reptiles is more perfect compared to the skeleton of amphibians and is characterized by the progressive development of bone elements, strengthening of the limbs and the strength of their attachment to the axial skeleton, which is associated with life on land.

An important feature of the lizard’s skull is its almost complete ossification; minor remains of cartilage are observed only in the olfactory and auditory areas. Especially a large number of integumentary ossifications form the roof, sides and bottom of the skull. The skull articulates with the spine through a single condyle formed by the occipital bones.

A characteristic feature of the skull of reptiles is the presence of peculiar pits in the temporal region. The temporal pits and the bone bridges that limit them - the temporal arches - were formed as a result of the long evolution of the outer roof of the skull of ancient reptiles.

The skull, while maintaining its strength, became lighter. This feature also contributes to the strengthening of the muscles that compress the jaws, which have become more massive and, when contracted, enter the temporal pits.

The visceral skeleton is greatly changed. The teeth sit on the maxillary, premaxillary, pterygoid and mandibular bones. Unlike amphibians, there are no teeth on the vomer.

The spine is divided into four sections. In a lizard, like in all reptiles, the spine is composed of a significant number of vertebrae. Biconcave (amphicoelous) vertebrae are an extremely rare phenomenon among reptiles; in most forms the vertebrae are anterior concave (procoelous).

A characteristic feature of reptiles is the appearance of a chest (absent in snakes and turtles), the formation of which is associated with the presence of ribs and sternum. The ribs articulate with the transverse processes of the vertebrae. True ribs articulate with the sternum; there are also freely ending false ribs.

The girdles of the limbs of reptiles are quite durable formations. In the lizard, a lot of cartilage is still preserved in the girdle of the forelimbs, but the girdle is firmly connected to the chest, and the support for the forelimbs is well expressed here. The skeleton of the forelimb is of a typical terrestrial type, but is still poorly developed.

The pelvic girdle is well developed, composed of three massive bones; at the place of their articulation, the acetabulum is formed, into which the head of the femur enters. Both halves of the belt are connected to each other through a cartilaginous layer.

Unlike amphibians, a double pubic-sciatic joint appears between both halves of the pelvis, which helps strengthen the pelvis. The ilium of each side is attached to the transverse processes of the two sacral vertebrae behind the acetabulum.

The skeleton of the hind limb retains the structure usual for terrestrial vertebrates.

Topic: Characteristics of birds

Birds are a progressive branch of reptiles (adapted to flight.

The most important features that distinguish birds from reptiles include:

1. Further development of the nervous system, higher complexity nervous activity and perfection of the senses, especially vision and hearing.

2.High and constant body temperature.

3. A perfect method of moving through the air by flying, which does not entail loss of the ability to move on the ground or climb.

4. Reproduction is accompanied by such complex biological phenomena as nest building, incubation of eggs, feeding and protection of chicks, which ensure increased survival of the offspring.

The noted features allowed the birds to spread widely throughout to the globe.

Among vertebrates, constant body temperature, or homeothermy, first arose in birds. This happened due to the complete separation of arterial and venous blood flows (four-chamber heart and one aortic arch) and intensive supply of tissues with oxygen. The latter increases the metabolic rate and causes the appearance of a constant body temperature.

Maintaining a constant body temperature is also ensured by the large size of the heart, which increases the speed of blood flow; the presence of heat-insulating feather cover that protects the body from cooling; extremely energetic breathing processes, providing an abundant supply of oxygen to the blood and excretion carbon dioxide; the presence of air sacs that increase the intensity of breathing and prevent the body from overheating during flight; rapid assimilation of food, promoting vigorous metabolism.

When analyzing the structure of birds, it is important to note, firstly, features that show their relationship with reptiles, and, secondly, features associated with flight.

The first signs include:

1) thin skin, poor in glands;

2) strong development of horny formations;

3) one occipital condyle;

4) intertarsal joint;

5) the presence of a cloaca, etc.

The second ones include:

1) transformation of the forelimbs into wings;

2) feather cover, which increases the load-bearing surface of the body and gives it a streamlined shape;

3) a decrease in body density due to the pneumaticity of the bones and the replacement of heavy jaws with a light, horny, toothless beak;

4) the keel of the sternum as the attachment point for the highly developed pectoral muscles that move the wings;

5) air sacs, which perform various functions, especially important for breathing during flight;

6) a number of skeletal features.

In addition, the tight fixation of the lungs in the body cavity, the absence of a bladder and asymmetry in the female reproductive system (almost all birds do not have a right ovary and a right oviduct) are also often associated with flight.

The skeleton of birds is durable and light, which is a consequence of their adaptation to flight. Strength is achieved both by the high content of mineral salts in the bones and by the complete fusion of individual bones. Lightness is due to the pneumaticity of many bones, resulting from bone marrow reduction. The air cavities of the bones are connected to the cavity of the air sacs. However, the relative mass of the skeleton (relative to body weight) in birds is approximately the same as in mammals (8-18% and 6-14%, respectively), although in the latter the bones are thicker and there are no air cavities in them. This is explained by the fact that in birds the relative length of the skeletal elements of the limbs and some other parts of the body is noticeably greater.

The forelimbs are transformed into wings. The bones of the hand are underdeveloped and lightweight, providing support for long flight feathers. Due to the transfer of the function of walking and grasping only to the hind limbs, a complex sacrum develops in the process of evolution as a reliable support for them.

The spine is completely differentiated into 5 sections: cervical, thoracic, lumbar, sacral and caudal. The cervical spine is mobile, the vertebrae of the remaining sections grow together, forming a strong support for the body.

The sternum is strongly developed and bears a high crest, or keel, to which are attached large muscles that move the wings. The keel is absent only in flightless birds, such as ostriches, but is retained, however, in penguins, whose wings function when diving.

Low mobility of the spine, the presence of a large sternum and funnel-shaped processes on the ribs give the chest and the entire body special strength, which is of great importance during flight.

Topic: Characteristics of mammals

The perfection of organization allowed mammals to spread widely across the globe. Currently, they are absent only in the central part of Antarctica.

Based on the nature of their connections with their environment, several groups of mammals are distinguished: terrestrial, underground, arboreal, flying (aerial) and aquatic animals. In addition, there are transitional groups that clearly demonstrate the paths of adaptive evolution of this class of vertebrates.

In addition to viviparity and feeding offspring with milk, mammals are characterized by a number of characteristics; some of them are also found in other groups of vertebrates, some are not characteristic of all species of mammals, and only a few such characters are unique. Among these features:

· Presence of hair (fur), sweat and sebaceous glands

· A special type of brain structure (including strong development of the telencephalon, the transition to it of the functions of the main visual center and the control center for complex forms of behavior)

· The presence of three auditory ossicles of the middle ear, the external ear canal and the auricle

· Seven vertebrae in the cervical spine

Warm-blooded

· Four-chambered heart. One (left) aortic arch

Alveolar structure of the lungs

· Teeth sitting in the cells (alveoli) of the jaws; heterodontity (different teeth)

Anucleate red blood cells

In mammals, the spine is divided into five sections: cervical, thoracic, lumbar, sacral and caudal. Only cetaceans do not have a sacrum. The cervical region almost always consists of seven vertebrae. Thoracic - from 10-24, lumbar from 2-9, sacral from 1-9 vertebrae. Only in the caudal region their number varies greatly: from 4 (in some monkeys and humans) to 46.

True ribs articulate only with the thoracic vertebrae (rudiments can also be on other vertebrae). They are connected in front by the sternum, forming the rib cage. The shoulder girdle consists of two shoulder blades and two clavicles. Some mammals do not have clavicles (ungulates), while others have them poorly developed or replaced by ligaments (rodents, some carnivores).

The pelvis consists of 3 pairs of bones: iliac, pubic and ischial, which are tightly fused together. Cetaceans do not have a true pelvis.

The forelimbs are used by mammals to move on land, swim, fly, and grasp. The humerus is greatly shortened. The ulna is less developed than the radius and serves to articulate the hand with the shoulder. The hand of the forelimb consists of the wrist, metacarpus and fingers. The wrist consists of 7 bones arranged in two rows. The number of metacarpus bones corresponds to the number of fingers (no more than five). The thumb consists of two joints, the rest - of three. In cetaceans, the number of joints is increased.

The respiratory system of mammals consists of the larynx and lungs. The lungs are characterized by a large branching of the bronchi. The thinnest of them are the bronchioles. At the ends of the bronchioles there are thin-walled vesicles (alveoli), densely entwined with capillaries. The diaphragm is a characteristic anatomical feature of mammals. Plays an important role in the breathing process.

Mammals have a four-chambered heart. It consists of the right and left ventricles, as well as the right and left atria. The chambers of the heart communicate with each other and with the great vessels using valves. The heart supplies the body tissues with oxygen and nutrients, freeing them from waste products. Arteries have elastic walls, veins are equipped with valves inside. Mammals have one (left) aortic arch.

The kidneys in mammals are bean-shaped and located in the lumbar region, on the sides of the spine. In the kidneys, as a result of blood filtration, urine is formed, then it flows through the ureters into the bladder. From it, urine exits through the urethra.

In mammals, the forebrain and cerebellum are especially developed. The cerebral cortex is formed by several layers of nerve cell bodies and covers the entire forebrain. It forms folds and convolutions with deep grooves in most mammalian species. The more folds and convolutions, the more complex and varied the animal’s behavior. Mammals also have a well-developed peripheral nervous system, which provides them with the highest speed of reflexes. The sense organs include: 1. Organs of vision 2. Organs of hearing 3. Organs of smell 1. Organs of vision are of great importance in the life of mammals. Unlike birds, whose each eye sees objects separately, mammals have binocular vision. 2 The hearing organs contain the external auditory canal and the auricle. 3 The olfactory organs are located in the anterior and posterior sections of the nasal cavity.

The digestive system of mammals is the gastrointestinal tract, a tube that connects the mouth to the anus. The digestive system includes: oral cavity, salivary glands, pharynx, esophagus, stomach, intestines, anus.

Most mammals have teeth (except for monotremes, some cetaceans, lizards and anteaters). They are located in the cells of the jaw bones. There are four types of teeth: incisors, canines, false molars and true molars.

After entering the oral cavity, food is chewed with the teeth. The food is then moistened with saliva, which flows through the ducts from the salivary glands. This makes it easier to swallow and move down the esophagus. Under the influence of saliva, complex carbohydrates (starch, sugar) contained in food are converted into less complex ones. Salivary glands are highly developed in herbivores. A cow, for example, secretes 60 liters of saliva per day. In most animals, saliva has pronounced antiseptic properties.

The esophagus allows the bolus of food to enter the stomach.

Most mammals have a single-chamber stomach. In its walls there are glands that secrete digestive juice. But herbivorous mammals like deer, cow, goat, sheep, etc. have a multi-chambered stomach.

The intestine is divided into thin and thick. The small intestine includes the duodenum, jejunum and ileum. To the colon - the cecum, colon and rectum.

In the small intestine, food is digested under the influence of digestive juices. They are secreted by the glands of the intestinal walls, as well as by the liver and pancreas, which open into the initial part of the small intestine - the duodenum. Nutrients in the small intestine are absorbed into the blood, and the remains of undigested food enter the large intestine.

At the junction of the small and large intestines, the ileocecal valve is located, which prevents the forming feces from being thrown back into the small intestine. In the cecum, under the influence of bacteria, indigestible food substances change. Also, most mammals have a large amount of lymphatic tissue in the walls of the cecum, which makes it an important organ of the immune system. In many animals (for example, rabbits, beavers) the cecum has big sizes. In some animals it occurs with the appendix. In the colon, stool is dehydrated, accumulates in the rectum and is then expelled through the anus.

Topic: Animals listed in the “Red Book of Kazakhstan”

The vastness of the territory of Kazakhstan and the uniqueness of its geographical position in the very center of Eurasia have led to great diversity natural conditions and, accordingly, plant cover and animal life. According to the Book of the Genetic Fund of the Fauna of Kazakhstan, there are 835 species of vertebrates alone - fish, amphibians, reptiles, birds and mammals.

It includes 125 species and subspecies, 40 mammals or animals, 56 birds, 10 reptiles, 16 fish species, 3 amphibians.

Subject to special protection

· ungulates - goitered gazelle, Turkmen kulan, argali; Ustyurt, Altai, Karatau mouflons; tugai deer;

· predatory - Snow Leopard, Tien Shan Brown bear, sand cat, caracal, manul, honey badger;

· rodents - beaver, Menzbier's marmot, selevinia, five-toed and three-toed dwarf jerboas;

· insectivores - muskrat, long-spined hedgehog;

· waterfowl - Dalmatian and pink pelicans, whooper swan, flamingos, white and black storks;

· inhabitants of steppes and deserts - bustard, jack, lapwing, demoiselle crane; birds of prey - bearded vulture, kumai, golden eagle, imperial eagle, white-tailed eagle, falcons - peregrine falcon and saker falcon;

· reptiles - monitor lizard, yellow belly, mottled roundhead, ocellated foot-and-mouth disease, 4 species of snakes, amphibians - Semirechye newt;

· fish - Aral and Caspian salmon, Syrdarya silverfish and lysach (pike-like asp).

LABORATORY WORK PLAN

LESSON 1-2. EXTERNAL AND INTERNAL STRUCTURE OF THE LANCELLE

Target: study the features of the external and internal structure of Lancelet.

1. Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE ASCRANALIA - ACRANIA

CLASS Cephalochordates – SERNALONORDATA

REPRESENTATIVE LANCELATE – BRANCHIOSTOMA LANCEOLATUM

2. Tasks:

2.1. Consider the external and internal structure using wet preparations, micropreparations of longitudinal and transverse sections of the lancelet, and tables.

2.2. Draw the general location of the internal organs, a cross-section in the pharynx, and a diagram of the circulatory system.

Answer the questions.

Name the characteristics of the chordate type in skullless animals.

List the characteristics of invertebrates in Lancelet.

What is the primitiveness of Lancelet?

What is endostyle, name the functions of endostyle.

Tell us about the Lancelet's lifestyle.

What are the features of the external structure of Lancelet

Which organs are metameric in Lancelet?

Name the features of the internal structure of Lancelet

What is the meaning of Lancelet

LESSON 3-4. EXTERNAL AND INTERNAL STRUCTURE OF CYCLYSTOMES

Target: study the features of the external and internal structure, highlighting the features of specialization of cyclostomes.

1. Systematic position

TYPE CHORDATE - SNORDATA

CLASS CYCLYSTOMATES – SUCLOSTOMATA

REPRESENTATIVE LAMPIRE – LAMPETRA SP.

2. Tasks:

2.1. Consider the external and internal structure and skeleton of the lamprey.

2.2.Draw the general location of the internal organs, diagram of the circulatory system, brain (top view), skull (side view).

Answer the questions.

1. Name the primitive features of the lamprey

3. What are the progressive features of the lamprey compared to the lancelet?

4. What is the external structure of the lamprey?

5. What are the features of the internal structure of the lamprey?

6. What are the features of the lamprey skeleton?

LESSON 5-6. EXTERNAL AND INTERNAL STRUCTURE OF CARTILAGE FISH

Target: study the structural features of cartilaginous fish, highlighting progressive features.

1. Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

SUPERCLASS OF FISH - PISSES

2. Task:

2.1. Consider the external and internal structure of the katran.

Answer the questions.

1. Name the primitive features of cartilaginous fish

2. What are the progressive features of cartilaginous fish?

3. Name the features of specialization of cartilaginous fish

4. Features of the external structure of a shark

5. Features of the internal structure of a shark

6. What is the connection between the reproductive and excretory systems in male cartilaginous fish?

LESSON 7-8. SKELETON OF CARTILAGE FISH

Target: study the skeletal features of a shark

1. Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

SUPERCLASS OF FISH - PISSES

CLASS CARTILAGE FISHES – CONDRICNTНУЭС

SUBCLASS Elasmobranchii –ELASMOBRANCHII

SUPERORDER SHARK – SELACHOMORPHA

REPRESENTATIVE OF KATRAN – SQUALAS ACANTHIAS L.

2. Tasks:

2.1. View the skeleton of a shark

2.2. Sketch the cheren (side view), the skeleton of paired limbs and their belts.

Answer the questions.

1. Name the parts of the shark skeleton

2. What are the progressive features of the skeleton of sharks compared to cyclostomes?

3. Explain the structure of a shark’s skull

4. Name the parts of the spine

5. What is the structure of an amphicoelous vertebra?

6. Explain the structure of the shoulder girdle of a shark

7. Explain the structure of the pelvic girdle of a shark

8. What elements does the skeleton of a shark’s paired limbs consist of?

LESSON 9-10. EXTERNAL AND INTERNAL STRUCTURE OF BONE FISH

Target: study the structure of bony fish, noting features that differ from cartilaginous fish.

1. Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

SUPERCLASS OF FISH - PISSES

FAMILY PERCIDAE – PERSIDAE

2. Tasks:

2.1. Examine the external and internal structure of the perch (perform an autopsy).

To open the fish, take it in your left hand with its belly up. We insert the sharp end of the scissors into the anus and make a cut along the abdominal side of the body to the head, all the way to the mouth. In this case, you need to press the scissors from the bottom up, without putting their ends deep, so as not to damage the internal organs. After the longitudinal incision, we place the fish on its right side, insert the blunt end of the scissors into the incision made near the anus and cut the body wall upward, towards the lateral line. We will make a second transverse incision in the area of the gill cover. Next, we will make a longitudinal cut along the lateral line, connecting both transverse cuts. Unscrew the resulting flap of fabric and remove it. Cut off the gill cover and shoulder girdle. Let's consider the general location of the internal organs.

To expose the brain, the skull cap must be carefully removed. Take the perch in your left hand with your back up, head away from you. Let's make a transverse incision with scissors in the back of the braincase in the occipital area. We will make the side incisions along the edges of the skull forward. Let's finish the job with a cross-section in the front of the head (just in front of the eyes). Grab the roof of the skull with tweezers and carefully remove it.

To view the brain from below, you need to cut the medulla oblongata and tilt the brain forward. It will be held by large optic nerves that go to the base of the skull and form the chiasm.

2.2. Draw the general location of the internal organs, the brain, and a diagram of the circulatory system.

Answer the questions.

1. What are the differences between bony fish and cartilaginous fish?

2. Features of the external structure of perch

3. Features of the internal structure of perch (digestive system, respiratory system, circulatory system, excretory system, reproductive system, nervous system)

LESSON 11-12. SKELETON OF BONE FISH

Target: study the features of the skeleton of bony fish, noting features that differ from the skeleton of cartilaginous fish.

1. Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

SUPERCLASS OF FISH - PISSES

CLASS BONE FISHES – OSTE1SNTNUES

SUBCLASS Ray-finned – ACTINOPTERIGII

SUPERORDER BONEY FISHES – TELEOSTEI

ORDER Perciformes – PERCIFORMES

FAMILY PERCIDAE – PERSIDAE

REPRESENTATIVE RIVER PERCH – PERSA FLUVIATILIS

2. Tasks:

2.1. Examine the skeleton of a crucian carp.

2.2.Draw the skull (side view), the structure of the trunk vertebra, and the girdle of the limbs.

Answer the questions.

1. Name the sections of the perch skeleton

2. What is the simplification of the skeleton of a perch compared to the skeleton of a shark?

3. Explain the structure of the perch’s brain skull

4. Explain the structure of the visceral skull of a perch

5. Name the parts of the spine

6. Describe the structure of the shoulder girdle of a perch.

7. Describe the structure of the pelvic girdle of a perch.

8. What elements make up the skeletons of paired limbs of a perch.

LESSON 13-14. EXTERNAL AND INTERNAL STRUCTURE OF AMPHIBIDES

Target: study the structural features of the frog, highlighting features associated with aquatic and terrestrial environments.

1. Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

CLASS Amphibians - AMRN1B1A

ORDER TAILALS – ANURA

2. Tasks:

2.1. Examine the external and internal structure of the frog (perform an autopsy).

To open it, put the frog in the bath with its belly up and, stretching its limbs, attach them with pins. Using tweezers to pull back the skin at the back of the abdomen, use scissors to make a small transverse incision in front of the base of the limbs. Then we will insert the scissors into the hole formed and from here we will make a longitudinal incision of the skin along the midline of the body up to the chin (in order not to damage the underlying organs, when cutting, it is necessary to pull the scissors upward). At the level of the forelimbs, we cut the skin perpendicular to the longitudinal section to the base of the forelimbs. We turn the resulting flaps of skin to the sides and secure them with pins. After that, let's look at the opened muscles and some blood vessels.

Continuing the dissection, we cut the wall of the body cavity in the same way as the skin. You just need to make a longitudinal incision not along the midline, but on the side of the abdominal vein, in order to avoid bleeding. When cutting the bones of the forelimb girdle, care must be taken to avoid damaging the underlying heart. After this, we turn to the sides and secure the muscle flaps with pins, reattach the forelimbs (their tension has weakened after cutting the shoulder girdle) and carefully rinse the preparation with water. We do not recommend removing any of the internal organs. You can only carefully straighten the intestines and place them next to the animal.

To study the structure of the brain, we remove the skin from the animal’s head. Then we make a small transverse incision just behind the head. Having bent the frog's body along the cut, we insert the tip of the scissors into the opened occipital region and carefully cut the skull from the side to the eye. We do the same on the other side. Using tweezers, carefully lift the incised roof of the skull upward, bend it forward and cut it off.

2.2. Draw the general location of the internal organs, the brain (top view), and a diagram of the circulatory system.

Answer the questions.

1. Name the differences between the skin of amphibians and the skin of fish.

2. Traits of amphibians associated with the aquatic environment.

3. Traits of amphibians associated with access to land.

4. Tell us about the external structure of a frog.

5. Features of the internal structure of the frog (digestive, respiratory, circulatory, excretory, reproductive, nervous systems).

LESSON 15-16. EXTERNAL AND INTERNAL STRUCTURE OF REPTIENTS

Target: study the structure of reptiles using the example of a lizard, noting the features of terrestrial existence.

1. Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

GROUP MAXILLA - GNATHOSTOMATA

ORDER SQUAMATA – SQUAMATA

2. Tasks:

2.1. Examine the external and internal (carry out an autopsy) structure.

2.2. Draw the general location of internal organs, the brain, a diagram of the circulatory system

To open it, we secure the lizard with pins in the bath with its back down. We make a longitudinal skin incision from the anal shield to the edge of the jaw just along the midline of the abdominal side and move the edges of the incision to the sides. Having prepared the skin, where necessary, from the underlying muscles, we thus expose the abdominal wall of the body. The muscles fit very tightly from the inside to the skin, so cutting the skin must be done very carefully. It is necessary to cut the pectoral cartilage and the episternum lying in front of it along with the pectoral muscles. This incision is made back to the cloaca, and the fusion site of the pubic bones of the pelvis is cut. Having turned both halves of the abdominal wall to the sides, you need to pin them to the bath with pins.

To open the brain, we separate the head from the body of the lizard and then, without removing the skin, open the skull from the back and sides, and then remove the roof of the skull with tweezers. By cutting off all the nerves at the base and carefully lifting the brain with the handle of a scalpel or tweezers, you can remove it from the remains of the braincase.

Answer the questions.

1. What are the progressive features of reptiles.

2. Tell us about the external structure of the lizard.

3. What is new in the structure of reptiles compared to amphibians.

4. What is neopallium.

5. How does the suction type of breathing differ from the pressure type.

6. What are the features of the digestive, respiratory, circulatory, reproductive, and nervous systems.

LESSON 17-18. Amphibian SKELETON

Target: study the features of the skeleton, highlighting the features of terrestrial existence.

1. Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

GROUP MAXILLA - GNATHOSTOMATA

SUPERCLASS TETRAPODA - TETRAPODA

CLASS Amphibians - AMRN1B1A

ORDER TAILALS – ANURA

REPRESENTATIVE FROG – RANA SP. L.

2. Tasks:

2.1. Examine the skeleton of a frog

2.2. Draw a skull, limb girdles, and the skeleton of paired limbs.

Answer the questions.

1. Name the progressive features of the frog skeleton

2. What are the primitive features of the amphibian skeleton?

3. What are the features of specialization of the frog skeleton?

4. What parts of the spine are distinguished in a frog?

5. Explain the structure of the shoulder girdle

6. Explain the structure of the pelvic girdle

7. What elements does the skeleton of the fore and hind limbs consist of?

LESSON 19-20. REPEAT SKELETON

Target: study the features of the lizard skeleton, highlighting features that differ from the frog skeleton.

1.Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

GROUP MAXILLA - GNATHOSTOMATA

SUPERCLASS TETRAPODA - TETRAPODA CLASS REPTILES - REPTILIA

SUBCLASS LEPIDOSAURS - LEPIDOSAURIA

ORDER SQUAMATA – SQUAMATA

FAMILY TRUE LIZARDS – LACERTIDAE

REPRESENTATIVE LIZARD – LACERTA SP. L.

2.Tasks:

2.1.Look at the skeleton of a lizard

2.2. Sketch the skull (side view), shoulder and pelvic girdles.

Answer the questions

1. Give a general description of the reptile skeleton.

2. What type of vertebrae do reptiles have?

3. What sections is the spine differentiated into?

4. What are atlas and epistropheus.

5. What are the features of the lizard skull.

6. What are the differences between the limb girdles and the skeleton of free limbs.

LESSON 21-22. EXTERNAL STRUCTURE OF BIRDS

Target: study the external structure of birds, highlighting features associated with flight.

1.Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

GROUP MAXILLA - GNATHOSTOMATA

SUPERCLASS TETRAPODA - TETRAPODA

BIRD CLASS – AVES

2. Tasks:

2.1. Consider the external structure of birds

2.2. Sketch the types of feathers, the structure of the feather, the structure of the fan

Answer the questions.

1. What features of the external structure of birds are associated with flight.

2. Explain the structure of a feather.

3. What types of feathers are distinguished, their functions.

4. What are pterilia and apteria.

5. What is molting, what is it connected with.

LESSON 23-24.BIRD SKELETON

Target: study the skeleton of birds, highlighting features associated with flight.

1.Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

GROUP MAXILLA - GNATHOSTOMATA

SUPERCLASS TETRAPODA - TETRAPODA CLASS BIRD CLASS – AVES

SUPERORDER TYPICAL BIRDS – NEOGNATHAE

ORDER COLUMBIFORMES – COLUMBIFORMES

REPRESENTATIVE ROCK DOVE – COLUMBIA LIVIA.

2. Tasks:

2.1. Examine the skeleton of birds, highlighting features associated with flight.

2.2. Sketch the skull, shoulder and pelvic girdles of the limbs.

Answer the questions

1. Name the skeletal features associated with flight.

2. What sections is the spine differentiated into?

3. What is a keel, its purpose.

4. Which parts of the spine are included in the complex sacrum.

5. What is a heterocoelous vertebra.

6. Describe the shoulder girdle.

7. What are the features of the pelvic girdle.

8. Describe the structure of the skeletons of free limbs.

LESSON 25-26. INTERNAL STRUCTURE OF BIRDS

Target: study the internal structure of birds, highlighting features associated with flight

1.Systematic position

TYPE CHORDATE - SNORDATA

SUBTYPE VERTEBRATES, OR CRANIALS - VERTEBRATE, OR CRANIOTA

GROUP MAXILLA - GNATHOSTOMATA

SUPERCLASS TETRAPODA - TETRAPODA

BIRD CLASS – AVES

SUPERORDER TYPICAL BIRDS – NEOGNATHAE

ORDER COLUMBIFORMES – COLUMBIFORMES

REPRESENTATIVE ROCK DOVE – COLUMBIA LIVIA.

2. Tasks:

2.1. Examine the internal structure of birds (perform an autopsy).

Before proceeding with the dissection, you should make sure that the birds have very voluminous air sacs. To do this, you need to insert a thin glass tube connected to a rubber bulb into the laryngeal slit lying behind the root of the tongue, and, squeezing and releasing the latter, begin to force air into the windpipe. Soon you can see how the skin on the sides of the neck, in the armpits, and on the belly will swell, the sternum will rise and the volume of the bird’s body will increase greatly. This is the result of the air sacs filling with air. Birds have several air sacs: two cervical, one interclavicular, two or three pairs of thoracic and one pair of very large abdominal ones.

Let's put the bird on its back and, pulling the skin up, make a skin incision with scissors along the clearly visible keel of the sternum and then continue it forward along the middle of the neck to the beak (do not damage the crop) and back - almost to the cloaca opening. Then, pulling the skin with tweezers and cutting the underlying layers of tissue with a scalpel, we separate the skin from the muscles and turn it to the sides.

Continuing the opening, we will use a scalpel to make a deep longitudinal incision in the pectoral muscle in its middle part, stepping back from the keel by about a centimeter. We cut it until we see the shiny surface of the fascia of the subclavian muscle, which lies under the sternum.

Next, we will make a longitudinal incision along the midline of the abdominal wall from the posterior edge of the sternum to the opening of the cloaca, and from leading edge This incision consists of transverse incisions along the posterior edge of the sternum. Next, cut with scissors on the right and. on the left are the ribs and bones of the shoulder girdle and remove the sternum along with the coracoids and fork. Now you can see the internal organs in their natural position.

To open the brain, we remove the skin from the entire head, and then use scissors to cut the bones around the skull in a circle from approximately the level of the ear hole to the top of the eye. Next, grasping the edges of the bone with tweezers, remove the entire roof and break off the sides of the skull. Then we cut it with scissors and take out the upper arches of the first 2-3 cervical vertebrae. We cut across the opening section of the spinal cord and, gradually turning it anteriorly, separate it, and then the head m

Chordata ( Chordata listen)) is a phylum of animals that includes vertebrates, larvalochordates, and anecranates. Vertebrates such as birds and fish are the most famous, and are the subphylum of animals to which humans belong.

Chordates have bilateral symmetry, which indicates the existence of a line of symmetry dividing their body into two halves, which are almost mirror images of each other.

Bilateral symmetry is found not only in chordates, but also in (although in the case of echinoderms they are bilaterally symmetrical only during the larval stage of their life cycle, and in adults pentaradial symmetry appears).

All chordates have a notochord, which is present for some or all of their life cycle. The notochord (or dorsal string) is a semi-flexible rod to which the animal's large muscles are attached. It also plays an important role in signaling and coordinating development.

The notochord consists of flat chordae enclosed in a fibrous sheath. In vertebrates, the dorsal chord is present only during the embryonic stage of development, and then the vertebrae develop around it and form the spine. In tunicates, the notochord remains throughout the animal's life cycle.

Chordates have a single, hollow dorsal nerve cord that runs down the animal's back and, in most species, forms the brain at the front of the body. They also have gill slits, which serve as openings between the pharyngeal cavity and the external environment, as well as for filtering water.

Another characteristic of chordates is a structure called the endostyle, a groove-like organ that lies against the wall of the pharynx and secretes mucus and traps small food particles that enter the pharyngeal cavity. The endostyle is present in tunicates and lancelets. In vertebrates, the endostyle is replaced by the thyroid gland, an endocrine gland located in the neck.

Main characteristics

chord;
neural tube (cord);
gill slits;
endostyle or thyroid gland;
muscle tail.

Species diversity

The phylum chordata includes more than 75,000 species of animals.

Classification

Chordata are classified in the following taxonomic hierarchy:

Domain: Eukaryotes ( Eukaryota);
Kingdom: Animals ( Animalia);
Type: Chordata ( Chordata).

Chordates, in turn, are divided into the following subphyla:

Skullless ( Acrania) : There are now about 32 species of skullless. Representatives of this subphylum have notochords that persist throughout their life cycle. Lancelets are the only family of skullless fish whose members are marine animals with long, narrow bodies. Earliest known fossil lancelet, Yunnanozoon, lived about 530 million years ago during. Fossils of these organisms have also been found in the famous Burgess Shale in British Columbia.
Larval chordates, or tunicates ( Urochordata) : There are currently about 1,600 species of tunicates. This subphylum is divided into classes such as ascidians and appendicularians. Tunicates are marine filter feeders, most of which do not move but rather attach to rocks or other hard surfaces on the seabed.

To the question about general characteristics of the chordate type asked by the author Begimai Usonova the best answer is Despite the enormous diversity, all representatives of the Chordata type are characterized by common organizational features that are not found in representatives of other types. Let's look at the main characteristics of the type using an interactive diagram:
The body is bilateral - symmetrical.
The intestine is through.
Above the intestines is the notochord.
Above the chord, on the dorsal side of the body, the nervous system is located in the form of a neural tube.
The walls of the pharynx have gill slits.
The circulatory system is closed. The heart is on the ventral side of the body, under the alimentary canal.
They live in all living environments.
Source: biology

Answer from Lady by the Fireplace[guru]
The phylum Chordata is divided into three subphyla: aneschunates, tunicates, and vertebrates. Despite the wide variety of species, the body of all chordates has a common structural plan and consists of a head, torso, tail and limbs. Main feature representatives of the type is the presence (at least at one of the stages of individual development) of the notochord - a flexible, elastic cord that acts as an axial skeleton. The notochord is located above the intestine and is formed from the endoderm by splitting off a cellular cord from the dorsal side of the intestinal tube.
Despite the exceptional diversity of chordates, they all have a number of common structural and developmental features. The main ones are:
1. All chordates have an axial skeleton, which initially appears in the form of a dorsal string, or notochord. The notochord is an elastic, non-segmented cord that embryonically develops by lacing it from the dorsal wall of the embryonic intestine: the notochord is of endodermal origin. The subsequent fate of the chord is different. It is preserved for life only in lower chordates (with the exception of ascidians and salps). In most representatives, the notochord is reduced to one degree or another due to the development of the spinal column. In higher chordates it is an embryonic organ and in adult animals it is to one degree or another replaced by vertebrae; in connection with this, the axial skeleton from a continuous unsegmented cord becomes segmented. The spine, like all other skeletal formations (except for the notochord), is of mesodermal origin and is formed from a connective tissue sheath surrounding the notochord and neural tube.
2. Above the axial skeleton is the central nervous system of chordates, represented by a hollow tube. The cavity of the neural tube is called the neurocoel. The tubular structure of the central nervous system is characteristic of almost all chordates. The only exceptions are adult tunicates. In almost all chordates, the anterior part of the neural tube grows and forms the brain. The internal cavity is preserved in this case in the form of the ventricles of the brain. Embryonic, the neural tube develops from the dorsal part of the ectodermal primordium.
y. U lower forms gills are located on their walls. Gill slits are preserved for life only in lower aquatic chordates. In others, they appear only as embryonic formations, functioning at some stages of development or not functioning at all.
Along with the indicated three main features of chordates, the following characteristic features of their organization should be mentioned, which, however, in addition to chordates, are also present in representatives of some other groups. Chordates, like echinoderms, have a secondary mouth. It is formed embryonically by rupture of the gastrula wall at the end opposite the gastropore. In place of the overgrown gastropore, an anal opening is formed. The body cavity in chordates is secondary (coelom). This feature brings chordates closer to echinoderms and annelids.
The metameric arrangement of many organs is especially clearly expressed in embryos and lower chordates. In their highest representatives, due to the general complexity of the structure, metamerism is weakly expressed.
Chordata are characterized by bilateral (bilateral) symmetry of the body. As is known, in addition to chordates, many groups of invertebrate animals possess this trait.
Evolutionarily, chordates are characterized by morphophysiological continuity in all organ systems, which can be traced in changes in homologous organs.

Answer from Yana[guru]

Answer from Ivan Yarish[guru]
. All chordates have an axial skeleton or notochord.

3. The anterior (pharyngeal) section of the digestive tube communicates with the external environment by two rows of openings, called visceral clefts

Answer from Nikita Shurshilin[newbie]
All chordates have an axial skeleton or notochord.
2. Above the axial skeleton is the central nervous system of chordates, represented by a hollow tube. In almost all chordates, the anterior part of the neural tube grows and forms the brain.
3. The anterior (pharyngeal) section of the digestive tube communicates with the external environment by two rows of openings, called visceral clefts
the presence of a chord instead of a spine. lack of bones

Chordata on Wikipedia
Check out the Wikipedia article about Chordata

Chordates include about 40 thousand various types individuals that differ from others in structure, lifestyle, and habitat.

The Paleozoic era contributed to the emergence of this type of animal approximately 500 million years ago. Scientists suggest that their ancestors were annelids.

Chordates settled throughout the planet and became habitual inhabitants of the sea, land, air and even soil.

What is a chord and who are chordates?

The internal structure of chordates is different from others. They are characterized by the presence of an axial skeleton - the vertebral column, which is otherwise called the notochord.

It was this feature of the structure of the spine that gave the name to chordates.

Structural features

The following features are characteristic of chordates:

The location of the neural tube above the axial skeleton and the formation of the spinal cord from it.
The presence of a rod - a chord.
Absence of intestines in the caudal region.
Location of the heart under the digestive tract.

Phylum Chordata (chordata) - examples of animals

Representatives of chordates:

Origin and evolution of chordates

Biology as a science considers the origin of chordates to be one of the most important stages development of the historical world of animals.

The emergence of this type meant the emergence of new animals with a unique structure, which allowed them to further evolve into creatures with maximum complexity in structure and behavior.

Some scientists believe that chordates began to exist even before the appearance of annelids, which fed by filtration. Other scientists attribute them to the ancestors of chordates.

One way or another, the evolution of annelids, or, as they are also called, benthic worm-like animals, gave birth to new types: echinoderms, pogonophorans, hemichordates and chordates.

Subsequently, chordates evolved in three directions, depending on their lifestyle:

The habitat of individuals of the first direction was hard ground. This contributed active development a filtering apparatus that provides nutrition during a sedentary lifestyle, and the formation of a thick protective shell over the entire surface of the body. These individuals have the ability to reproduce asexually. This is how tunicates appeared.
The habitat of individuals of the second direction is the bottom. They moved a little more, digging into the ground. This lifestyle simplified their original organization. The development of the myochordal complex required increased mobility, and the growth of the pharynx added new gill slits. This branch has survived to this day in the form of the skullless.
The habitat of individuals of the third direction, which began to lead a floating lifestyle, is fresh water. There was a transition to active nutrition and increased mobility. The nervous system and sensory organs became more sophisticated, which led to more complex behavior and the emergence of more complex forms. This is how a group of vertebrates appeared.

In rivers and other fresh waters, jawless ones also formed, from which jawed ones later separated. They expanded their habitat to salt water and became the progenitors of modern groups of fish.

Later, amphibians separated from fish. Then they came to land, and thus a new species appeared - reptiles.

General characteristics of the type Chordata

The cover consists of two layers of leather. Upper layer represented by the epidermis and its derivatives: scales, feathers, wool, hair. This layer of skin contains scent glands that produce mucus and sweat. The bottom layer is the dermis, consisting of fibrous connective tissue.

Musculoskeletal system presented in the form of a skeleton consisting of a notochord and connecting tissue of the membrane. The skeleton of the head is divided into the brain and facial parts.

Fish develop jaws, and vertebrates develop two pairs of limbs. Bones are connected by joints.

The respiratory system in lower chordates is represented by gills, and in vertebrates by lungs. In addition, the skin of chordates is partially involved in gas exchange.

The digestive system of cephalochordates is a straight tube and almost undeveloped digestive glands. In vertebrates, this is the digestive canal, which has sections.

Food first enters the oral cavity, then passes into the pharynx, begins to be processed in the esophagus, passes into the stomach and finally enters the intestines. In addition to the listed organs, vertebrates have a liver and pancreas.

The circulatory system is closed. In vertebrates, due to an increase in metabolic intensity, the heart appeared and became more complex. Cephalochordates do not have a heart.

In birds, the heart differs from the heart of reptiles only in the presence of a complete septum and the absence of the left aortic arch; Mammals have a four-chambered heart that pumps two types of blood: arterial and venous.

The central nervous system (CNS) of chordates has the form of a neural tube with an internal canal, which in vertebrates forms the brain. The peripheral nervous system includes the cranial and spinal nerves that arise from the central nervous system.

The excretory system of all chordates, except lancelets, is represented by paired kidneys, ureters and a bladder.

Reproductive system: reproduction occurs using testes in males and ovaries in females. Tunicates are hermaphrodites; they reproduce sexually and asexually. Other chordates have sexual division.

Classification of chordates and their subtypes

Chordates are divided into lower (lamprey, lancelet, hagfish) and higher (reptiles, amphibians, fish, birds, mammals).

The following subtypes are distinguished:

skullless;
tunicates;
jawless;
primary: classes of fish;
tetrapods: classes of amphibians or amphibians, reptiles or reptiles, birds, mammals.

What characteristics of chordates does a person have?

In humans, like chordates, in the early stages of development, the formation of the axial skeleton, i.e., the notochord, occurs. The musculoskeletal system in humans is represented, as in vertebrates, by the supporting internal skeleton.

Humans also have the following characteristics of chordates:

central nervous system, which has a tubular structure;
a closed circulatory system with the main circulatory organ - the heart;
a breathing apparatus capable of communicating with the external environment through the pharynx, nasal cavity and mouth.

Monkey eel

Some interesting information:

The importance of chordates is very great; they are classified among the most diverse and numerous types. At the moment, there are about 50 thousand species of chordates. The presence of a common feature in all individuals - the notochord (supporting organ) - gave the name to this type of animal.

The anatomical features of chordates are similar to echinoderms. The lowest representatives of chordates are lancelets, which retain their main character throughout their lives.

This is the most highly organized group of animals that have mastered various habitats. Modern classification type:

Subtype Skullless (Acrania)

Subphylum Larvalchordata (Urochordata)

Subphylum Vertebrata

Section Agnathans - Agnatha

Superclass Jawless - Agnatha

Class Cyclostomata - Cyclostomata

Section Gnathostomata - Gnathostomata

Pisces superclass - Pisces

Class Cartilaginous fish - Chondrichthyes

Class Bony fish - Osteichthyes

Superclass Quadrupeds, or Terrestrial vertebrates - Tetrapoda

Class Amphibians, or Amphibians - Amphibia

Class Reptiles or Reptiles - Reptilia

Bird Class - Aves

Class Mammals, or Beasts - Mammalia

All chordates have an internal skeleton , the main axial element of which is the chord . The notochord arises from the endoderm and is an elastic cord formed by large vacuolated cells. From the outside, the chord is covered by a connective tissue membrane. The notochord serves to support the muscles and is involved in the movement of the animal. Throughout life, the notochord is retained only in the lower representatives of the type. In vertebrates, the notochord is present in embryonic development and is then replaced by the spine. The spine performs the same functions as the notochord.

The central nervous system of chordates has a tubular structure. The neural tube is formed from the ectoderm and is located above the notochord. Inside it there is a canal called the neurocoel.

In the anterior section of the digestive tube, chordates have gill slits. Gill slits connect the pharyngeal cavity with the external environment. In aquatic vertebrates (fish), gills are formed in the gill slits - organs of aquatic respiration. In terrestrial vertebrates, gill slits are present only in embryos at the initial stages of individual development.

In the abdominal part of the body, under the digestive tube, there is a heart, from which blood moves in an anterior direction.

Chordates are bilaterally symmetrical animals, deuterostomes, deuterostomes.