Features of the internal structure of chordates. Type chordates

Type Chordates combines animals that are very diverse in appearance, lifestyle and living conditions. Representatives of chordates are found in all the main environments of life: in water, on the land surface, in the thickness of the soil and, finally, in the air. They are geographically distributed throughout the world. The total number of species of modern chordates is approximately 40 thousand. The Chordata type includes non-cranial (lancelets), cyclostomes (lampreys and hagfish), fish, amphibians, reptiles, birds and mammals.

As shown by the brilliant studies of A. O. Kovalevsky, the chordates also include a peculiar group of marine, largely sessile, animals - tunicates (appendicularia, ascidians, salps). Some signs of similarity with chordates are found by a small group of marine animals - enteropneusta, which are sometimes also included in the chordate phylum.

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, initially appearing in the form of a dorsal string, or chord. The notochord is an elastic, non-segmented strand that develops embryonically by lacing it from the dorsal wall of the germinal gut: the notochord is of endodermal origin. The subsequent fate of the chord is different. It persists for life only in lower chordates (with the exception of ascidia and salps). In most representatives, the notochord is reduced to one degree or another in connection with the development of the spinal column. In higher chordates, it is an embryonic organ and in adult animals it is to some extent displaced by the vertebrae, in connection with this, the axial skeleton becomes segmented from a continuous non-segmented cord. The spine, like all other skeletal formations (except the chord), is of mesodermal origin and is formed from a connective tissue sheath surrounding the chord 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 neural tube grows and forms the cerebrum. The internal cavity is preserved in this case in the form of the ventricles of the brain. Embryonally, the neural tube develops from the dorsal part of the ectodermal bud.

3. The anterior (pharyngeal) section of the digestive tube communicates with the external environment with two rows of holes, called visceral fissures. In lower forms, gills are located on their walls. Gill slits are preserved for life only in lower aquatic chordates. For the rest, 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, besides chordates, representatives of some other groups also have. chordates, as well as

1. Type Chordates

Chordates are divided into lower (Cranial and Tunic) and higher (Vertebrates).

Typical signs of chordates:

1) the presence throughout life or 1 of the period of the dorsal string - a chord that acts as an internal axial skeleton. During ontogenesis, it is replaced by the spinal column, which becomes a vertebra.

2) The central nervous system has the form of a tube, its internal cavity is a neurocoel, it is connected by a neuropore to the external environment. The neural tube lies above the chord, is divided into 2 sections - the spinal cord and the brain.

3) the digestive tube - its anterior section - the pharynx - performs 2 functions - digestive and respiratory. The pharynx is pierced by gill slits, in water gills appear in their place, in terrestrial ones, lungs appear as protrusions of the pharyngeal wall.

4) the circulatory system is in the form of a tube, the heart is located on the ventral side under the chord and digestive tube.

Features that unite with invertebrates:

Secondority, is formed by breaking through the wall of the gastrula. In place of the gastropore, a posterior opening is formed.

The secondary cavity of the body - the whole

The presence of metamerism - the segmental arrangement of organ systems

Bilateral, bilateral symmetry

Subtype Cranial

Origin:

According to A.N. Severtsov, the ancestors of the non-cranial were free-swimming, bilaterally symmetrical animals. This group gave rise to two branches. One retained a free-swimming lifestyle and led to vertebrates. The other has adapted to a sedentary, near-bottom or burrowing lifestyle. Subsequently, some non-cranial animals moved to life in the bottom soil, they developed metallural folds and a peribranchial (atrial) cavity (lancelets and epigonichths). The other part remained to live in the water column (amphioxides).

Systematics. Class Cephalothordates

Sem. Brachiostomy- lancelets (European, Asian)

Sem. Amphioxide- signs of larvae are characteristic, 1.5 cm.

Sem. Epigonichthids- differ in asymmetry, small lancelets up to 5 cm.

The body is elongated, laterally compressed. The body is covered with a fin fold, in the region of the back it is called the dorsal fin, which passes into the caudal fin, then into the caudal fin, metapleural folds pass along the gods of the body, they merge with the caudal folds. The skin of the lancelet consists of 2 layers:

Single layer epidermis (unicellular glands, f mucus - protective)

Thin gelatinous connective tissue - cutis, or corium

Muscular system: 50-80 segments are adjacent to the chord - myomers. The segments are separated by myoseptae (septa).

CNS: There is only a chord in the head. The neurocoel is the rudiment of the ventricle of the brain. In larvae, it communicates with the external environment through the neuropore. In adults, in place of the neuropore - the fossa of Kelliker - the organ of smell. The spinal and abdominal nerves depart from the neural tube.

Digestive system. Breath: The pharynx performs 2 functions - it is an organ of digestion and respiration. The walls of the pharynx are pierced by gill slits. They breathe oxygen dissolved in water. At the bottom of the pharynx there is a groove - endostyle, on which there is a glandular and ciliary epithelium: it secretes a large amount of mucus. The intestines are in the form of a straight tube, ending with an anus.

excretory system: Nefridial. In the anterior part above the pharynx lies about 100 pairs of nephridia (a short strongly curved tube with holes).

Reproduction: Dioecious. There are sex glands. Females have ovaries, males have testes. There are no genital ducts. Mature germ cells enter the atrial cavity through cell ruptures. Fertilization is external, the development of the egg in water.

2. Subtype larval-chordata (tunicates)

Tunicates are a branch of chordates. All typical signs of chordates are developed only in the larval stage. Some species lead a sedentary lifestyle, while others move slowly in the water column. All marine animals feed passively by filtering water flows. Hermaphrodites. Asexual reproduction by budding. The circulatory system is of an open lacunar type.

Ascidia class. 3 Squads:

Neg. solitary sea squirts- gastroascidia or spherical.

Neg. Synascidia, or Colonial- colonies are connected with other bases, united by a common tunic, have independent oral siphons. Fertilization is possible between different colonies.

Neg. Pyrosomats, or Firemen- an ascidian-like zooid is formed from a fertilized egg. there is an oral and cloacal siphon. there is a sole. The body is covered with a tunic.

Tunic layers:

1) hard cuticle outside, under the cuticle - a fibrous network impregnated with tunicin (methane-like substance.

2) two-layer mantle, or musculoskeletal sac: 1. layer - epithelium, skin, two-layer. 2. transverse muscle fibers.

Digestive system, nutrition: Mouth → huge pharynx (gill openings - stigmas; endostyle). The pharynx is a respiratory organ. There is a heart - tubular, the edges are reduced alternately, creating a pendulum-like movement of blood.

Organs of excretion and reproduction: renal vesicles, throughout life there is an accumulation of urea crystals. Sex cells enter the water through the cloacal siphon. They are captured by the oral siphon of another individual. Fertilization is external. A tailed larva is formed, which differs sharply from the adult organism in structure. The larva breaks the egg membranes → goes out into the environment. Swimming 2-3 hours. attached to the substrate → regressive metamorphosis.

Salpa class- floating, sea.

Neg. True salps- colonies exist for a short time.

Neg. kegs- polymorphic colonies

Outwardly, the body resembles a cucumber or a barrel, dressed in muscular ribbons. The entire body is occupied by the atrial and pharyngeal cavities, separated by a dorsal outgrowth. The successive contraction of the muscle bands from the anterior end of the body drives water from the pharynx into the atrial cavity and pushes it out with force → the salpa jerkily moves forward. Salps are characterized by alternation of sexual and asexual reproduction - metagenesis. The asexual salpa develops from the fertilized egg. A kidney stolum is formed on the ventral side of the body, it grows, buds form on the sides, and turns into a chain of daughter individuals. One egg matures in the ovary. Sperm enters the cloacal siphon and fertilizes the egg there. The egg matures in the ovary, breaks the egg shells and comes out. The mother's body dies. The fetus is growing.

Appendicular class- floating. A small oval body from which a tail extends. 1 pair of gill openings. From the base to the tail stretches the chord, neural tube, muscle cords. There is no real tunic. The ectodermal cells of the mantle secrete mucus with a chitin-like substance. With the movement of the tail, the mucus is knocked into a kind of house. Opposite the oral siphon, a lattice of thickened threads of mucus is built. With a blow of the tail, he breaks the house and leaves it. Floats for a while. Builds a new house in 2 hours.

Development and reproduction: In sexually developed individuals, the spermatozoa come out. Eggs mature in the ovary. Sperm enters the ovary, fertilization occurs. An embryo is formed in the eggs, it grows, leaves the mother's body. Comes out. It looks like an adult, differs only in size.

3. Subtype Vertebrate or Cranial

The main features of the organization of vertebrates

Body Shape: In aquatic vertebrates, the body is divided into the head, trunk, and tail. Terrestrials have a variety of body shapes. The cervical region appears, the mobility of the head increases. Unpaired fins are reduced, paired ones turn into limbs. In aquatic limbs, they again turn into fins.

Skin covers: two-layer skin: 1) outer - epidermis, (from ectoderm) 2) inner - corium (dermis) (from mesoderm). Function: protection, metabolism, thermoregulation.

Skeleton: Represented by departments: skull, axial, limb girdles, skeleton of free limbs

Axial skeleton: in the evolutionary series - the chord is replaced by the vertebral column. The spinal column is differentiated, the cervical, thoracic, lumbar, sacral, caudal regions appear.

skull skeleton: The medulla closes the brain. On the sides of the chord, parachordalia are formed, in front of the lateral cartilages and trabeculae. In bony fish, the skull remains cartilaginous, and a shell forms on top. In bony bones, ossification occurs, primary or cartilaginous bones are formed. There are 2 types of brain skull: platybasal - a wide base of the skull, the brain is located between the eyes (fish, amphibians, some reptiles) and tropibasal - the eye sockets are close together, the brain part is behind the eyes (birds, mammals). There are several types of attachment of the brain apparatus to the brain skull:

1) protostyle - the jaw and hyoid arches are suspended from the skull (primitive maxillary)

2) hyostylia - the pendant is attached to the auditory part of the brain skull

3) amphistyly - the upper element of the jaw arch is connected to the skull with the help of special processes (sharks, bone ganoids)

4) autostyly - the upper element of the jaw arch fuses with the skull.

Musculature: Skeletal, smooth, cardiac. Water has a segmental structure (metomeric). With the transition to the ground image, ribbon-like muscles (muscles) are formed. In higher vertebrates, the metomeric structure remains only in the location of the muscles of the spinal column.

CNS: It consists of the brain and spinal cord. The neural tube is differentiated into 2 sections: the head and dorsal. In the anterior part, 3 brain bubbles are formed: anterior, middle, posterior. Further differentiation leads to the formation of 5 departments. From the anterior part of the anterior cerebral bladder, the brain is formed. The back of the anterior cerebral bladder turns into the diencephalon. There are 12 pairs of cranial nerves. Aquatic - 10.

Sense organs: Vision - twin eyes. Organs of hearing: anatomically connected with the organ of balance. In higher, the spiral coiled canal (cochlea) is the organ of hearing. The organs of smell are immersed in the skin. The organs of taste: taste buds are an accumulation of sensitive and supporting cells. In fish on the fins, in others in the mouth.

Digestive system: Starting with the ancient jaws, the oral apparatus is sucking, in modern cyclostomes it is a suction funnel, in fish, a mouth apparatus armed with teeth is being formed. At the bottom of the oral cavity, a tongue with its skeleton (sublingual apparatus) is formed. In the oral mucosa scattered taste buds. The pharynx in aquatic is permeated with gill slits, in terrestrial ones the lungs are connected with it. Pharynx-esophagus-stomach. Sections of the stomach: the cardial part (the esophagus empties), the bottom or fundus part, the pilar intestine (differentiates). Intestines: large intestine, small intestine, rectum. It ends either in the cloaca or the anus.

Respiratory system: Gill slits develop in aquatic animals, gill sacs develop in jawless fish, gill filaments develop between gill slits, which together make up gills. The main function is gas exchange. Amphibians have respiratory organs - lungs.

Circulatory system: Skullless - closed. The heart first appears in cyclostomes as an expansion of the abdominal aorta. First, the heart is 2-chambered. Further 3-chamber (amphibians, reptiles). Starting with amphibians - 2 circles of blood circulation: small and large.

excretory system:

Vertebrate larvae develop a pronephros or pronephros. It is represented by a collection of nephridia. The main element of the kidney is the Malpighian bodies. Amniotes develop pelvic buds (metanephros).

reproductive system: Most are dioecious. The ovaries have a granular structure, the testes are smooth. For anamnia, external fertilization is characteristic, in some internal. Eggs develop only in the aquatic environment. There is a live birth. In amniotes, embryonic membranes appear, the amount of yolk increases. Development is not in the aquatic environment.

4. Section Jawless (class Cyclostomes)

The most ancient primitive vertebrates. They reached their heyday in the Silurian-Devonian. By the end of the Devonian, most of them died out. their remains have not been found. Groups of modern jawless appeared in the Carboniferous.

class cyclostomes

Includes modern jawless. 2 subclasses. The most ancient class. Representatives (lampreys, hagfishes) are characterized by a worm-like shape, bare mucous skin, a mouth opening in the depth of the suction funnel, no jaws, a cartilaginous visceral skeleton, an axial chord covered with a thick mucilaginous membrane - a fatty cushion that covers the spinal cord. Respiratory organs - gill bags (5-16 pairs). They live in the seas and fresh waters. There are unpaired fins.

P / cl. Lampreys

1Neg. Lampreys- 3 groups are distinguished by habitat:

1) Marine or anadromous lampreys- live in the seas. They go to rivers to spawn. Representatives: Atlantic, Caspian.

2) river lamprey- Inhabit coastal areas of the seas. Spawning in rivers. Representatives: European river, Japanese.

3) Impassable river, lake, stream lampreys- small, live in one place all their lives, do not migrate.

P / cl. Mixins– incl. 2 groups

Mixin group- Gill sacs flow into the common subcutaneous canal, which opens outwards with 1 opening.

Bdelostoma group- each gill sac opens outward. 5 to 16 gill sacs.

Unpaired fins. The caudal fin is equal-bladed, there are 2 dorsal fins. In females, an anal fin develops before spawning. The hagfish do not have developed dorsal fins.

covers: the epidermis is multi-layered, numerous skin cells lie in it, secrete abundant mucus (protection).

Skeleton and muscular system: Myochordal complex There is a notochord. The skull is not formed, is at an evolutionary stage, surrounds the brain only from below and from the sides. Visceral skeleton: consists of 3 sections:

a) The skeleton of the preoral funnel - elasticity

b) Gill skeleton - closes the toad sacs

c) Pericardial cartilage - clothes the heart.

The muscular system consists of muscle segments - myomers, separated from each other by partitions - myoseptae.

Digestive organs and nutrition:

Respiration and gas exchange: Respiratory organs - gill sacs. Gas exchange occurs in the capillaries of the walls of the gill sacs.

Respiratory tract: in lampreys: Mouth → pharynx → breathing tube → internal openings of gill sacs → 7 pairs of gill sacs → external openings of gill sacs on the side walls of the body. At the mixin: Oral opening → pharynx → independent openings of gill sacs (5-16 pairs) → gill sacs → gill canal opening outward.

Circulatory system: Closed, 1 circle of blood circulation. There is a 2-chambered heart, 1 atrium and 1 ventricle. Hematopoiesis is carried out in the walls of the esophagus and intestines, in the kidneys, liver.

excretory system: Excretory organs - paired mesonephric (trunk) kidneys located on the dorsal side of the body above the gonads

Reproductive system and reproduction: Separate sexes. The sex glands are paired (ovary or testis), occupy almost the entire abdominal cavity of the body. There are no sexual ducts. Fertilization is external. Lamprey eggs are small. die after spawning and fertilization. They breed once in a lifetime. The larva is a sandworm. After 4-5 years, metamorphosis occurs, the gerbil turns into an adult lamprey. Hagfish have large eggs, development without metamorphosis, a young individual hatches from the egg, differing from the adult only in size. Polycyclic.

Nervous system: The head of the brain is small, lies in the same plane. 5 parts of the brain lie without leaning on each other. The medulla oblongata passes into the spinal cord.

Sense organs: Chemical sense organ: nasohypophyseal sac: Unpaired nostril → nasal passage → olfactory capsule - pituitary outgrowth. Lateral line organ - perception of water currents, registration of the approach of objects. There are weak electrical organs, temperature, tactile receptors and chemoreceptors.

5. Section Jaws. Superclass Pisces. Class Cartilaginous fish

Their earliest fossil remains in the form of scales were found in the Upper Silurian deposits. Representatives of very diverse groups are already found in the Devonian deposits. One of the earliest groups known from the early Silurian are armored fish, their body was covered with a bone shell. They lived until the Carboniferous and then became extinct. Another group were small freshwater acanthodia whose body was covered with bone plates. Actually cartilaginous fish known from the late Silurian - early Devonian. Lamellarbranchs survived two bursts of adaptive radiation - in the Silurian - Devonian and in the early Mesozoic. From the end of the Mesozoic, modern families of this subclass took shape.

External structure: Marine. Torpedo body. paired fins appear: pectoral, ventral. The skin is naked or covered with placoid scales. The function of the axial skeleton is performed by the spinal column. The skull is giostelic. 5-7 pairs of gill slits open on the sides of the body. In whole-headed they are covered by a common gill cover. An arterial cone develops in the heart, and a spiral valve develops in the intestine.

Covers: Fish skin consists of 2 layers:

1) upper - epidermis - multi-layered, it contains a large number of glands that secrete mucus (protective function)

2) corium - the actual skin or dermis - scales are located. The scales consist of plates and a spike lying on it. The main substance is dentin, covered with enamel, the cavity is the pulp, vessels and nerves - such scales are placoid.

Skeleton and muscular system: The skeleton is cartilaginous. The skeleton consists of sections: skull, axial skeleton, free fin skeleton, fin girdle. The axial skeleton is represented by the vertebral column: 2 sections - trunk and tail. The vertebrae are amphicoelous (biconcave). The skull consists of 2 sections - cerebral and visceral. The medulla consists of the olfactory and auditory capsules, the rostrum (snout), and the orbit. Visceral - consists of 3 arches: gill, hyoid, jaw. Musculature consists of myosepts,. Feature- autonomy of the muscles - the muscles can contract with a violation of the central nervous system.

Digestion and nutrition: Predators and filtrates. rectal gland (reservoir for the accumulation of salts). Large, three-lobed liver (up to 25% of body weight), source of vitamin A.

Respiratory system: They breathe oxygen. Respiratory organs - gills.

Inhalation-exhalation mechanism: When inhaling, the gill arches diverge to the sides. Water enters the mouth, then into the pharynx, passes into the external gill slits. When you exhale, the gill arches approach each other, water is pushed out.

Circulatory system: The heart consists of a venous sinus, atrium, ventricle, abdominal aorta, it begins with an arterial cone. For the first time, the spleen appears, which lies near the stomach and performs the function of a blood depot, is a hematopoietic organ.

The organs of excretion - the kidneys (trunk), in the form of ribbon-like bodies lie immediately under the spinal column.

reproductive system: Dioecious, fertilization is internal. Males: testes - vas deferens - renal tubules - Wolffian canal - cloaca - female reproductive tract. The eggs are large, covered with a horn-like shell.

CNS: Brain - 5 departments: anterior, posterior, oblong, middle, intermediate. The medulla oblongata passes into the spinal cord. 10 cranial nerves leave the brain.

Sense organs: The main receptor is the sense of smell - The olfactory sacs communicate with the external environment through the nostrils. Capable of echolocation - capturing waves reflected from the bottom and objects. Seismosensory organs - lateral line, holes. Ampoules of Lorenzini - allows you to find prey. Eyes with a large crystal, fixed eyelid. Organs of hearing: only the inner ear.

Systematics

The class is divided into 2 subclasses: P/Cl. elasmobranchs And P/Cl. Whole-headed.

1) P/Cl. elasmobranchs

· N/neg. sharks

Neg. Placiformes

Neg. Polygills

Neg. Miscellaneous

Neg. Lamellae:Sem. fox sharks, Sem. Herring, Brownie shark

Neg. Carchariform or sawtooth:Sem. Giant, Sem. Grey, Sem. feline

Neg. Catranoid (spiny) sharks

Neg. Sawtoothed

Neg. Squatinous or sea angels

N/neg. stingrays

Neg. Sawfish (sawfish)

Neg. Rough-like

Neg. Diamond-shaped or diamond-shaped slopes

Neg. Eaglet or stingray:Sem. Orlyaki, Sem. horned rays

Neg. Gnus-like or electric rays

2) P/Cl. Whole-headed- the body is valky, skin ossifications - gill covers are developed. The skull is autostylic. Teeth merge into dental plates. The interbranch septa are reduced. Neg. Chimera The first dorsal fin has a spike. Tail in the form of a tourniquet. Marine. The female lays 1-2 eggs with a filiform appendage.

6. Class Bony fish

General characteristics:

Bone scales develop in the skin. Skull hyostylic or amphistylic (loosely attached to cranial box). The tail is hetero-, homo-diphycercal. 5 pairs of gill slits covered by a common gill cover. A swim bladder is formed. Some have lungs (double breathing), some retain the arterial cone (cross-finned), others are replaced by the aortic bulb. Fertilization is external, in some internal - there is a capulative organ - an outgrowth of the anal fin. Neutral buoyancy - 2 types: open and closed bubble. Functions of the swim bladder: hydrostatic, participation in gas exchange, is a baroreceptor, creation and amplification of sounds.

Covers: Consists of 2 layers:

1) multi-layered epidermis - a large number of glands that secrete mucus

2) corium - cells are colored, called chromatophores - provide a color change under the action of the central nervous system. Scales are protective bony formations in the skin. The crossopterans have cosmoid scales in the form of a bone plate, externally covered with cosmin. Ganoid scales, covered with ganoid, arose from the cosmoid. Ganoid scales can fuse with each other, forming a shell. Normal scales - cycloid - in the area of ​​the lateral line in the scales there are holes that communicate with the lateral line canal.

Digestive system: There is a language. The glands secrete saliva without food enzymes. There is a liver, spleen, gallbladder.

Respiratory system: 2 types of breathing: air and water. Aquatic: oxygen from water - gills. Air - from the air - the swim bladder, lungs, sections of the intestinal mucosa.

Excretory organs, water-salt metabolism: kidneys, gill apparatus, skin, digestive tube, liver. filtering apparatus of the kidneys, many vascular glomeruli - glomerulus

reproductive system: Dioecious. Males have testes, females have ovaries. In crossopterygians, the reproductive and excretory systems are connected, the vas deferens flows into the kidney. The Wolfian canal is the function of the vas deferens and ureter, the Müller canal is the function of the oviduct. care for offspring.

CNS and sensory organs: The brain is divided into 5 sections: anterior (olfactory lobes). Intermediate brain. Midbrain (2 visual lobes). The cerebellum covers the medulla oblongata. Eyes.

SYSTEMATICS:

1. P / class. lobe-finned- scales cosmoid or bone. The notochord persists throughout life. The paired fins are covered with scales. Beaded fin. In the intestines there is a spiral valve, in the heart - an arterial cone. There is a cesspool.

1) N/neg. CrossopterygiansNeg. coelacanths

2) N/neg. Dipnoi Neg. Horn-toothed or one-lung,Neg. Bipulmonary

2. P / class. ray-finned- ganoid or bone scales. There are naked, with shells. Joan is not. The fins are formed by bone rays - lipidotrichia → name. The arterial cone is replaced by the aortic bulb. Instead of light swim bladder.

Cartilaginous ganoids

Neg. sturgeons Sem. Sturgeon Fam. paddlefish

Neg. Polyperiformes

Bone ganoids

Neg. Amieformes

Neg. shell-shaped

3. P / class. bony- bone scales. High degree of ossification. Bone rays supporting the leathery edge of the gill cover are developed. In the heart, instead of an arterial cone, an aortic bulb appears. The swim bladder is devoid of cellularity. The intestine does not have a spiral valve. 1 dorsal fin, the second, if present, without bone rays - fatty.

1 ) N/neg. Clupeoid (herring)

Neg. herring Sem. Herring Sem. Anchovies

Neg. salmon

Neg. cetaceans

Neg. Myctophiformes

2) N/neg. Aravanoid

Neg. Aravaniformes

Neg. beaked

3 ) N/neg. Angveloid

Neg. eels

Neg. Saccular

Neg. Spinosiformes

4) N/neg. Cyprinoids

Neg. Cypriniformes

Neg. Catfish

7) N/neg. percoid

Neg. Sticklebacks

Neg. Cithale-shaped

Neg. Perciformes

Neg. Flatfishes

IN THE OREN. REGION: family of Karpovs (rudd, asp, tench, podust, gudgeon, bleak, crucian carp, carp). from the loach family from the catfish family from the perch family, zander, bersh, perch, from the cod burbot family.

7. Superclass Quadrupeds. Class Amphibians or Amphibians

Class 4 - Amphibians, reptiles, birds, mammals.

Amphibians - anamnia (primary aquatic): 1) the main development in the aquatic environment 3) there is a stage of metamorphosis 4) eggs develop without the formation of embryonic membranes

Origin and evolution. The transition of vertebrates from an aquatic to a terrestrial way of life is accompanied by the appearance of breathing atmospheric oxygen and movement on a solid substrate. In parallel, other organ systems also changed: integument, blood circulation, sensory organs, and the nervous system. The first amphibians that appeared in fresh water at the end of the Devonian are ichthyostegida. They were true transitional forms between lobe-finned fish and amphibians, they had the rudiments of a gill cover, a real fish tail. The skin was covered with small fish scales. However, along with this, they had paired five-fingered limbs of terrestrial vertebrates. Later, in the Carboniferous period, a number of branches arose ( labyrinthodonts). In the Carboniferous, a second branch of primary amphibians also arose - lepospondylus - stegocephalic(shell-headed) for a solid shell of skin bones that covered the cranium. The ancestors of stegocephals were bone fish. They are closest to stegocephals lobe-finned fish. Stegocephalians survived until the beginning of the Mesozoic. Modern detachments of amphibians are formed only at the end of the Mesozoic. intensive speciation of modern amphibians began in the early Mesozoic.

Amphibious class. Adults are characterized by paired limbs with a hinge joint, unequal. The skull is attached to 1 cervical vertebra, an atlas is formed - the occipital joint (the head is mobile). The upper element of the hyoid arch - pendants - turns into the auditory ossicle of the middle ear - the stirrup. The pelvic girdle is connected to the transverse processes of the sacral vertebrae. 2 circles of blood circulation are formed, but they are not completely separated. The lateral line organs disappear in adults. Signs of aquatic animals: 1) the skin is permeable to water 2) trunk (mesonephric) kidneys 3) body temperature depends on the ambient temperature - poikilothermia . Eggs are laid only in water. Larva → metamorphosis → adult.

Leather: Consists of 2 layers: epidermis (multilayered) and corium (thin, with capillaries). The skin is rich in glands that secrete mucus. In those living in dry places, this mucus thickens, forms a film, and reduces moisture loss. The secret can be poisonous (toad, toad). The corium contains pigment cells. The cells of the epidermis become keratinized, claws and nails appear. The legless have bony scales scattered in the corium. Anurans under the skin have lymphatic lacunae - reservoirs that allow, under favorable conditions, to accumulate water supplies.

Muscular and digestive system: The muscles of the limbs increase, the oral cavity becomes more complicated. All adults are carnivorous; larvae can feed on algae and detritus. Prey is captured with the help of the tongue. There is a pancreas, a liver.

Respiratory system: Respiratory function - skin, lungs, mucous membranes of the oropharyngeal cavity. In larvae, this function is performed by the skin, external and internal gills. Breathing mechanism: ventilation of the lungs occurs due to the movement of the bottom of the oropharyngeal cavity.

Circulatory system: The heart is 3-chambered. Blood mixes in the ventricle. Hollow veins appear, they are paired, formed by mixing 3 veins, mixed blood. The bone marrow appears for the first time.

Excretory organs, water-salt metabolism: Larvae have head buds (probuds). During metamorphosis, trunk buds appear. There is a bladder. Decay products: in larvae - ammonia, in adults - urea.

reproductive system: paired sex glands. The function of the oviduct is the Muller canal.

In males: testes → vas deferens → kidney, where they open into the Wolf canal, the lower part of which forms a swelling - the seminal vesicle (reservoir for storing reproductive products). In anurans, fertilization is external (in males, genital calluses are on the paws to hold the female). In caudates - internal. Neoteny - the ability of larvae to sexual reproduction (ambystoma, axolotl) (under unfavorable conditions)

CNS, sense organs: The larvae have lateral line organs. The sense of smell is well developed, there are external nostrils. Jacobson's organs are necessary for the perception of the smell of food in the mouth. The organs of vision are developed in almost everyone. Developed color perception.

Systematics

P / Class Arcuvertebral

N/neg. Jumping

Neg. Primitive anurans

Neg. tailless- flattened body, small limbs, large head. Hind limbs powerful pushing.

Sem. round-language- Protective coloring. Midwife toad - the female lays eggs in the form of cords, the male fertilizes and carries on her paws until hatching.

Sem. pip- Surinamese pipa - the female lays eggs on her back, the male fertilizes and presses into the skin. Cells are formed around the eggs. They stay there until they become frogs.

Sem. spadewort

Sem. toads– Representatives: yeah, leaf frogs. in Russia - gray and green toads. Behind the eyes there are poisonous glands - parotids.

Sem. tree frogs- the tips of the paws are expanded into disks (suckers). Caring for offspring. Representatives: blacksmith tree frog (they build a pool where they lay eggs), marsupial tree frog - on the back of a bag where eggs are laid

Sem. real frogs- Goliath frog, brown, grassy, ​​green frogs

Sem. copepods

P/Class Thin Vertebrates

Neg. Tailed- the body is compressed from the sides, a small head, a tail-balancer, limbs on the sides, small, equal

Sem. Siren- descended from the neotenic larvae of the ambistome. There is no adult stage. There are only forelimbs, external gills are preserved throughout life, there are lungs

Sem. Proteic- Neotenic salamander larvae. There are external gills. Fertilization is internal. Representatives: European, American. Proteus

Sem. real salamanders- gills are reduced, there are ovoviviparous and viviparous

Sem. Tritons- winter on dry land. Representatives: common newt and comb

Sem. Lungless salamanders

Neg. legless- Representative: worms - a worm-like body, a small head. Constrictions divide the body into segments. Limbs and their belts are absent, there is no tail, at the end of the body there is a cloaca. They secrete poisonous mucus. Underground lifestyle, some aquatic. Viviparous.

8. Class Reptiles or Reptiles

Amniotic signs:

1) Embryonic development in the air with the formation of embryonic membranes (serous, amnion, allantois)

2) The eggs are large, covered with a shell

3) Internal fertilization

4) Strengthening care for offspring

5) No larval stage

Origin of reptiles: Terrestrial vertebrates arose in the Devonian. These were armored amphibians, or stegocephalians. They were closely associated with water bodies, since they bred only in water, lived near water bodies, where there was terrestrial vegetation. Rearrangements: adaptations for protecting the body from drying out, for breathing atmospheric oxygen, walking on a solid substrate. All these features took shape in reptiles. Mesozoic reptiles are primarily terrestrial animals. Many of them have adapted to life in the water. Some mastered the air environment. The oldest reptiles are known from the upper Permian deposits. North America, Western Europe, Russia and China. They are called cotilosaurs. Most of the groups have acquired greater mobility; their skeleton became lighter, but at the same time stronger. The solid shell of the skull has undergone a partial reduction. The present-day crypto-necked and side-necked tortoises to a greater extent preserve the primary appearance of the Triassic land tortoises. Marine and soft-skinned appeared in the late Mesozoic. crocodiles appear at the end of the Triassic. Jurassic crocodiles differ from modern crocodiles in the absence of a true bony palate. The vertebrae were still amphicoelous. Crocodiles of the modern type are descended from ancient archosaurs - pseudosuchians. They are known from the chalk. By the end of the Mesozoic more development received highly organized birds and mammals.

Covers. The skin is dry, devoid of glands, breathing is due to the movement of a closed chest (snakes do not have it). The skin is a multilayer epidermis. The upper one is the stratum corneum, the lower one is the Malpighian layer (living, germ). Skin ossifications (plates) lie in the skin. The skin has lost the ability to permeate water and gases. Under the epidermis there is a corium, in the upper layer of which there are pigment cells (coloration).

Skeleton. In the axial skeleton: cervical, thoracic, lumbar, sacral, caudal. In the cervical, the first 2 vertebrae are differentiated (atlas with epistrophy). The lumbar region has short ribs. Capable of autotomy (tail drop).

Circulatory system. An incomplete septum appears in the heart. Mixed blood with a predominance of arterial.

Digestive system: Mostly predators. In the oral cavity there are glands without enzymes. Poisonous ones are converted into poisonous ones. There is a liver, pancreas.

Excretory organs: The kidneys are metanephric, located in the pelvic cavity. 2 types of filtration:

1. those that live in water - a well-developed filtering apparatus (glameruli and nephron). Allocate products into the lumen by filtering the blood plasma. 2. in land animals - the secretory apparatus of the renal tubules is enhanced. The end product of metabolism is uric acid.

reproductive system: Dioecious.

CNS and sensory organs: The brain is enlarged. The olfactory lobes are developed, there is a pituitary gland and an epiphysis. The cerebellum is enlarged. There are 11 pairs of cranial nerves. The organs of hearing are the middle (the stirrup is in it) and the inner ear.

Systematics

1) P / cl. Anapsida (neg. Turtles)

2) P / class. Archosaurs (neg. Crocodiles)

3) P / class. Lepidosaurs (neg. Beakheads, neg. Scaled)

1) P / class Anapsida

Neg. Turtles- Modern ones have a shell consisting of a dorsal shield - a carapace and an abdominal one - a plastron. The carapace is formed by bone plates of skin origin. The ribs and trunk spine are fused with it. The plastron is formed from bone plates. From above, the shell is covered with horny shields. Only the caudal and cervical regions are movable; the rest is fused with the carapace. Jaws without teeth. Well developed lungs. Additional respiratory organs are paired anal bladders and outgrowths of the pharynx. Well developed vision, sense of smell. 5 suborders: P/neg. Hidden neck turtles Sem. freshwater,Sem. Land;P/neg. sea ​​turtles; P/neg. Soft-shelled turtles (soft-skinned); P/neg. Side-necked turtles; P/neg. Turtles

2) P / class. Lepidosaurs

Neg. beakheads- 1 view. Tuatara or Hatteria is the oldest species among modern ones. Up to 70 cm. Island New Zealand. Protected.

Neg. scaly

P/neg. Chameleons- a keel runs along the back. The limbs are transformed into grasping pincers in the form of 2 opposed groups of fingers. Eyelids fused.

P/neg. lizards – Sem. geckos; Sem. iguanas- sea, wood, land .; Sem. Agamas; Sem. real lizards- viviparous.; Sem. Fusiform; Sem. monitor lizards- the largest, arboreal, terrestrial; Sem. Yadozuby- 2 types. Poisonous; earless monitor lizards.

P/neg. Amphisbaena (two-walkers)

P/neg. snakes- Legless. They are able to open their mouth wide - a movable articulation of the bones of the facial part of the skull. Poisonous ones have poisonous glands and teeth. Belts and limbs are absent. Sem. Slepuns- digging lifestyle; Sem. false-footed; Sem. already shaped;Sem. aspids are mostly poisonous. Sem. sea ​​snakes. Sem. Vipers Sem. pitheads.

P / class Archosaurs

Neg. crocodiles

The body is valky, covered with horny scutes. The nostrils open on the tubercles, the eyes are raised above the surface of the muzzle. On the head and at the anus - odorous glands (mark the territory) lay up to 100 eggs, bury them in the sand. Live up to 180 years. Sem. alligators, Sem. real crocodiles, Sem. gharials– 1 species – Gavialus Ganveticus (Indostan)

9. Bird Class

Origin of birds. P their rarest were ancient lizard reptiles - archosaurs. By the beginning of the Mesozoic (Triassic) - birds. Birds are closest to the squad thecodonts. The evolution of the group proceeded by adapting to climbing trees, in connection with which the hind limbs served to support the body on a solid substrate, and the forelimbs specialized for climbing by grasping the branches with their fingers. Subsequently, the ability to jump from branch to branch developed. Scales, forelimbs formed feather rudiments of the wing plane. An important stage in the development of birds is the transformation of scales into feathers, which first developed on the wings and tail, and subsequently spread throughout the body. The appearance of feathers not only made it possible to fly, but also played a very important thermal insulation role, and determined the homoiothermy of birds. The immediate ancestors of birds have not yet been established. In the last century, in the Jurassic deposits were found and described archeopteryx. There are currently seven known fossil remains of Archeopteryx. Archeopteryxes are characterized by many features of reptiles: the absence of a horny beak, the presence of teeth, a narrow and keelless sternum, and abdominal ribs.

Covers: The skin is thin, dry, devoid of glands. The skin layer is divided into the skin itself - the dermis, blood vessels pass through it, the feathers are strengthened, and muscle fibers are located. The second layer - subcutaneous tissue - a loose layer adjacent to the muscles, accumulates fat reserves. One gland - coccygeal (well developed in waterfowl) - produces a fat-like secret. They lubricate the feather, prevent wetting, a source of vitamin D. The growth of the keratinized layer of the skin forms the horny cover of the beak - ramphoteka. Horny scales cover the fingers, prehensile, part of the lower leg. In some species, males form a bone outgrowth on the flail - a spur.

Pen types, structure: The main feather is contour, consists of a rod, 2 fans on the sides. The part of the trunk to which the fan is attached is called the stem. The lower part is the chin, fixed in a feather bag. Each fan is formed by horny plates - barbs of the 1st order, from which thin barbs of the 2nd order extend, with small hooks located on them. Hooks fastening with each other, form a plate of the fan. Pigments accumulate in feathers - melanins (black, brown color) and lipochromes (red, yellow, green). Contour feathers are fixed in the skin in special fields - pterylia, they alternate with fields where there are no quills of the feather - apterylia. Under the contour feathers - downy (thin rod, beards without hooks).

Propulsion system: The peculiarity of the structure of the neck muscles allows you to turn your head 180 0, owls 270 0. The thoracic vertebrae fuse into the dorsal bone, connect to the sacrum, the trunk is immobile. There is a large sternum with a process - a keel, for attaching the muscles involved in the flight. The tail vertebra turns into a coccygeal bone - a pigastil, the bases of the tail feathers are attached to it. The jaw turns into a beak. The clavicles fuse into a fork - the role of a shock absorber during a wing stroke.

Digestion: In filterers - the tongue is fleshy, in those who feed on nectar - it folds into a tube, in woodpeckers - with hooks. Salivary glands (some have amylase). Some have a goiter - an expansion of the lower part of the esophagus (temporary storage of food when the stomach is full; in pigeons, the cells of the goiter undergo fatty degeneration - bird's milk).

Breath: Through the nostrils, air enters the nasal cavity → choanae → oral cavity. There are 2 larynxes - the upper one (does not have vocal cords), behind which is the trachea, and the lower one (forms the vocal apparatus). Sounds are generated by vibrations as air passes through the eardrums.

Inhalation-exhalation is carried out due to the movement of the chest. Oxygen saturation occurs continuously during inhalation and exhalation (double breathing).

Isolation, water-salt exchange: kidneys → ureters → cloaca. The metabolic product is uric acid. A loop-like section appears in the nephron - the loop of Henle (water readsorption) - allows you to remove harmful substances.

reproductive system: In females: only 1 left ovary develops. Fertilization in the upper part of the oviduct. Holases (cords) - the dense part in the egg - allows the yolk to spin, the germinal disc will always be on top. The smaller the bird, the larger the clutch. Sexual dimorphism is pronounced.

Nervous system, sense organs: 12 pairs of cranial nerves. The main receptor is vision. Color vision. Recognize sweet, bitter, salty. Thermoreceptors, touch receptors.

Systematics:

Aquatic, near-water birds

N/neg. floating

Neg. penguins Neg. loons Neg. Toadstools.Neg. Petrel-like (Tube-nosed) Neg. Pelicans (Copepods) Neg. Storks (Archives) Sem. Herons, Storks, Ibises, Flamingos . Neg. Anseriformes

Birds of open landscapes

Neg. ostriches Neg. Nandu-shaped Neg. cassowaries Neg. Kiviformes (Wingless) Neg. Falconiformes P/neg. Amer. Vultures P/neg. falconsSem. Hawks, Falcons. Neg. Galliformes Neg. Cranes Sem. Real Cranes, Bustards Neg. Pigeons Neg. parrots Neg. cuckoo Neg. Owls Neg. Swift-shaped P/neg. Swifts P/neg. hummingbird Neg. Woodpeckers P/neg. Primitive woodpeckers P/neg. real woodpeckers Neg. passeriformes P/neg. Hornbeaks P/neg. Screaming P/neg. passerines Sem. Larks Sem. swallowtail Sem. crows Sem. Blue fam. Thrush Sem. Wagtail Sem. Starlings Sem. finches

10. Class Mammals or Animals

The progressive evolution of mammals has been associated with the acquisition of: high body temperature, the ability to thermoregulate, a high aerobic metabolic rate. This was facilitated by changes in the respiratory and circulatory systems: this was expressed in the division of the heart into four chambers and in the preservation of one aortic arch, which led to the immiscibility of arterial and venous blood, in the appearance of a secondary bone palate, which provided breathing during meals, accelerated digestion of food. changes in the structure of the jaws, differentiation of teeth, development of the jaw muscles. The animal-toothed reptiles closest to mammals were cynodonts. The most pronounced features of skeletal changes were found among them in thrinaxodon from the early Triassic. In the subsequent development of mammals, paleontologists emphasize changes in the dental system. This led to the separation of two groups - morganucodonthod And Cuneotheriidae→Eupantotherium. Biologically, they were to a certain extent close to terrestrial and arboreal insectivores. At the end of the Mesozoic, the division into two independent stems - Inferior, marsupials, And higher, placental. Most ancient group marsupials are a family of possums.

Placental mammals arose in the Cretaceous period. Fossil monkeys have been known since the Paleocene. tree monkeys - propliopithecus- gave rise to gibbons and close to anthropoids, Ramapithecus. Of great interest are australopithecuses. The class of mammals is of pyphyletic origin, i.e. its individual branches arose from different groups of animal-like reptiles. Modern mammals are divided into:

1) First passers (first beasts)

2) Real mammals (animals)

There are egg-laying mammals.

Covers: 1) Epidermis (multilayer, keratinized) → dermis → fiber. The epidermis is the lower layer of cells, they become keratinized and rejected (dandruff). Derivatives of the epidermis - hair, nails, etc. in the epidermis there is a pigment - melanin (coloring, tanning, protection from sunlight). 2) Corium (skin itself) - formed by fibrous tissue, rich in blood vessels. The lower layer of the corium is subcutaneous fat.

2 types of hair: outer (long, hard) and down (soft). The outer hair consists of a trunk protruding outward and the base of the bulb, reinforced in the dermis. Glands (derivatives of the epidermis): sebaceous - their ducts open into the hair bag. The secret lubricates the skin, hair; sweat - open anywhere on the surface of the skin (thermoregulation). A modification of the sweat glands is the mammary gland. There are sensitive hairs - virbis (touch), the root of which is in the blood gap.

Skeleton, muscular system: The number of bones increases. Axial skeleton - cervical, thoracic, lumbar, sacral, caudal. All have 7 cervical vertebrae. The thoracic region is a closed chest. There are false edges (do not connect). The skull has a zygomatic arch. Limb belt - scapula, clavicle. Free department - shoulder, forearm, hand. Belt of the pelvic limbs - pelvis (closed - fused with the help of bone fusion - symphysis), thigh, lower leg, foot.

Digestive system Oral apparatus - lips, teeth, tongue, cheeks, gums. Heterodontism (raznozubnost) - incisors, canines, small and large molars. Salivary glands - enzymes (amylase), a bactericidal substance (lysozyme), stomach - single-chamber (carnivores) and multi-chamber (herbivores), consists of departments - scar, mesh, book, abomasum.

Respiratory system: Breathing due to the movement of the chest. Oral or nasal cavity → larynx → trachea → lungs (ending with alveoli). 2 types of breathing - abdominal (predominant in herbivores) and chest (predominant in carnivores).

Circulatory system: 4-chambered heart, 2 atria, 2 ventricles.

Excretory organs: The kidneys are pelvic, metanephric (in the pelvic cavity). Consist of 2 layers - cortex and medulla. The unit of the kidney is the nephron. Metabolic products - urea.

reproductive system: In males: the testicles are placed in the scrotum. Around the testicles is the appendage of the testis (maturation of germ cells), from which the vas deferens opens on the seminal mound at the root of the penis. In females: paired ovaries → oviducts open next to the uterus. Types of uterus: double (2 bodies, 2 horns, 2 vaginas; in rodents), bicornuate (dogs, pigs), simple (in primates, humans), bifid. The cervix opens into the vagina. The ovaries mature in the follicle - Graf's vesicle. The egg enters the abdominal genital funnel. Fertilization occurs in the upper part of the oviduct.

Systematics

P / class Cloacae (first beasts) - The most primitive. They lay eggs and incubate them. Neg. single passSem. Yachidna- the body is covered with needles, have a beak. Sem. Platypuses- semi-aquatic, between the fingers of the membrane. They filter the water.

P/class Animals

N/neg. marsupials

Neg. marsupials- Babies are born prematurely, carried out in a pouch. There are mammary glands in the bag. Sem. opossums, Sem. carnivorous marsupials, Sem. Marsupial badgers (bandicoots), Fam. Couscous- herbivores, Sem. Kangaroo

N/neg. Higher Beasts (Placental)- capable of sucking milk

Neg. Insectivores Sem. Hedgehogs- in Orenb. Region - eared and common hedgehog, omnivores, Sem. Moles, Sem. shrews- the smallest - a tiny baby shrew (2-3 g)

Neg. Woolly wings (kaguans) Neg. Bats– echolocation, active at night

P/neg. fruit bats

P/neg. The bats They feed on blood, nectar, insects Sem. bagwings, Sem. fish-eating, Sem. False vampires, Sem. Vampires, Sem. Ordinary the bats

Neg. edentulous- characterized by underdevelopment of teeth. Sem. Anteaters,Sem. armadillos

Neg. Lagomorphs Sem. pikas, Sem. Hares

Neg. rodents Sem. beaver, Sem. squirrels, Sem. jerboas, Sem. Mouse, Sem. Hamsters, Sem. Agouti, Sem. Chinchilla

Neg. cetaceans- forelimbs - flippers, hind limbs are absent.

P/neg. baleen whales Sem. Smooth (real) whales, Sem. Gray whales, Sem. Stripes

P/neg. toothed whales-there are teeth (homogeneous). Sem. river dolphins, Sem. Sperm Whales, Sem. Dolphins

Neg. PredatorySem. Doggystyle, Sem. Raccoons, Sem. Bears, Sem. Cats, Sem. Hyenas

Neg. pinnipeds Sem. eared seals, Sem. real seals, Sem. walruses

Neg. Odd-toed ungulates- the phalanges of the fingers end in a hoof. Sem. Tapirs, Sem. Rhinos

Neg. artiodactyls- an even number of fingers

P/neg. Non-ruminants- simple stomach, 4-fingered limbs Sem. Pigs,Sem. Bakers,Sem. hippos

P/neg. Ruminants- The stomach is complex. Belching food - chewing gum. Sem. musk deer, Sem. deer, Sem. giraffes

P/neg. calluses- limbs have 2 fingers, devoid of hooves Sem. camels

Neg. Primates- 5-toed, plantigrade. 1 finger is opposed to the rest. Odd-toothed. Big brain, convolutions appear

P/neg. Lower primates (semi-monkeys)Sem. Tupai- primitive, woody Sem. Lemurs, Sem. Lori– arboreal, tropics

P/neg. Greater primates (monkeys) Section of broad-nosed monkeys: small marmosets, callimico and major capuchin monkey. Narrow-nosed section: Sem. Monkeys,Sem. Gibbon, Sem. hominids

The type includes about 43 thousand species of animals that inhabited the seas, oceans, rivers and lakes, the surface and soil of continents and islands. The appearance and size of chordates are varied, as are their sizes: from small fish and frogs 2–3 cm to giants (some species of whales reach a length of 30 m and a mass of 150 tons).

Despite the huge variety of representatives of the Chordata type, they are characterized by common features organizations:

1. The axial skeleton is represented by a chord - an elastic rod located along the dorsal side of the animal's body. Throughout life, the notochord is retained only in the lower groups of the type. In most higher chordates, it is present only at the embryonic stage of development, and in adults it is replaced by the spine.

2. The central nervous system looks like a tube, the cavity of which is filled with cerebrospinal fluid. In vertebrates, the anterior end of this tube expands in the form of bubbles and transforms into the brain, in the trunk and tail sections it is represented by the spinal cord,

3. The anterior part of the digestive tube - the pharynx - is permeated with gill slits, through which it communicates with the external environment. Terrestrial animals have gaps only in early period embryonic development, while in aquatic chordates they persist throughout life.

4. The circulatory system is closed, the heart is located on the ventral side, under the chord and digestive tube.

Rice. Diagram of the structure of a chordate animal

5. In addition to these distinctive features, which are characteristic only of chordates, they have the following: they are all bilaterally symmetrical, deuterocavous, deuterostome animals.

6. Type Chordata is divided into three subtypes and 12 classes. Let's consider the most important of them.

Subtypes and classes of chordates

The type of chordates includes three subtypes - Cranial, Larval - chordate and Vertebrates. Chordates have an internal skeleton-chord in the early stages of development. Chordates occupy the main environments of life: water, land-air and soil. These are bilaterally symmetrical three-layered animals. Chordates include fish, amphibians, reptiles, birds, and mammals.

Subtype non-cranial

Class lancelets

Lancelets are a small group of animals reaching several centimeters in length. The reason for such a strange name was that the rear end of the body of these animals is similar to the blade of a surgical knife - a lancet. The body of the lancelet is elongated, laterally compressed, its anterior and posterior ends are pointed. The head is not expressed.

Vertebrate subtype

Cartilaginous fish class

About 660 species belong to the class of cartilaginous fish. This group includes well-known sharks (frilled, tiger shark, katran) and rays (stingray, saw-fish, manta), combined into two separate superorders, as well as whole-headed (chimeras). These are mostly large animals - the whale shark reaches a length of 20 meters. Like all vertebrates, representatives of this class are bilaterally symmetrical animals.

Class bony fish - the most numerous group of vertebrates. It has about 20,000 species belonging to 4 subclasses: ray-finned, multi-finned, cross-finned, lungfish.

We list the main representatives of the class:

detachment of sturgeons - beluga, sturgeon, sterlet;

salmon-like detachment - salmon, salmon, trout;

detachment cyprinids - bream, carp, crucian carp, silver carp;

detachment cod-like - cod, hake, pollock;

perch-like detachment - perch, horse mackerel, mackerel, pike perch.

Bony fish inhabit a wide variety of water bodies: fresh (ponds, rivers, lakes) and salty (seas, oceans). The body shape of these animals is mainly fusiform, streamlined, which allows to reduce water resistance when swimming.

Bony fish are vertebrates that have a number of adaptations to an aquatic lifestyle:

The mode of transportation is swimming;

Streamlined body shape;

Fixed articulation of the head with the body;

Tiled-like scales;

The organs of motion are fins, which, in addition, perform the function of stabilizers (ensure the stability of the body in water) and depth rudders;

Breathing with gills;

The presence of a swim bladder;

A special organ is the lateral line.

Class amphibians (amphibians)

This class unites animals, the peculiarity of which is that adults can live both on land and in water. However, their reproduction and development of eggs almost always occurs in the aquatic environment. This class includes about 3000 species, divided into three orders:

A detachment of legless amphibians, represented by a small group of organisms with reduced limbs and a tail - caecilians;

A detachment of tailed amphibians, which includes salamanders, newts, proteas, sirens;

Order tailless amphibians, which has the greatest species diversity, including such animals as frogs, toads, tree frogs, spadefoot, toads.

Almost all amphibians are small in size. The body of adults is divided into the head, trunk, tail (caudate in the detachment) and two pairs of limbs (in worms, the limbs and their belts are reduced). In connection with landfall, the body of the majority is flattened in the dorsal-abdominal direction, and the head is movably articulated with the body. The skin of amphibians is naked, so water and gases can freely diffuse through it.

Class reptiles or reptiles

There are about 6600 species of reptiles in the world fauna. The living reptiles are grouped into the following groups:

Detachment of the Turtle (representatives: caiman turtle, green turtle);

Order Beakheads (a very ancient group with the only surviving species - the tuatara, which is found in New Zealand. Among modern reptiles, the tuatara is closest to the scaly order;

Order Scaly (these include animals such as chameleons, lizards, snakes);

Detachment Crocodiles (representatives: Mississippi alligator, Nile crocodile, etc.).

Representatives of the reptile class are real land animals. The development of adaptations for life on land allowed the ancestors of these animals to leave the aquatic environment and spread widely across the Earth. However, in all orders (with the exception of beakheads) there are forms that have passed to life in water for the second time.

bird class

This class includes about 8600 species of living birds. They are subdivided into two superorders. Superorder Penguins (or Floating). Representatives of this group (king penguin, little penguin, Galapagos penguin, etc.) are large animals, they cannot fly, the main mode of transportation is swimming. The forelimbs are modified into flippers. Penguins are common in the cold regions of the southern hemisphere - in Antarctica and the islands of the Subantarctic. The superorder New-palatine, or Typical birds, is represented by a large number of orders: ostriches, anseriformes, chickens, cranes, bustards, waders, gulls, owls, woodpeckers, parrots, passerines, etc. Almost all the features of birds are associated with the development of airspace and the presence of adaptations to flight. The body of birds has a streamlined aerodynamic shape. It is covered with feathers, which are divided into contour and down. The axial part of the pen is the rod and the core. Quite the feather is immersed in the skin, and the fans depart from the rod. In the contour pen, they are formed by barbs of the first order, bearing barbs of the second order, fastened together by small hooks in such a way that a plate is formed. The core of the down feather is thin, there are no hooks. A downy feather, the beards of the first order of which extend in a bundle from the quill, is called down. Contour feathers give the body a characteristic shape, while down feathers serve as a heat-insulating material. Periodically, birds change their plumage - molting.

Class Mammals (or Beasts)

The class mammals is the last of the classes of vertebrates we are considering, representing the most highly organized group in the entire animal kingdom. Mammals inhabit a wide variety of habitats; they can be found in tropical forests and arctic deserts, in mountains and in ocean expanses.

This class includes seemingly completely different animals: the blue whale and the common hedgehog, the African elephant and the squirrel, the bat and the kangaroo, etc. We also systematically belong to this group. What, nevertheless, is common between all these different creatures?

Mammals are characterized by the following features:

development of hair on the skin;

a large number of skin glands: sweat, sebaceous;

the presence of mammary glands that secrete milk;

feeding the young with milk and caring for the offspring;

live birth (with the exception of single pass);

constant body temperature - homoiothermia;

intensive flow of basic life processes;

four-chambered heart, two separate circles of blood circulation;

lungs of an alveolar structure, there is an epiglottis;

the presence of a diaphragm separating the abdominal and thoracic cavities;

teeth are differentiated into incisors, canines, premolars, molars;

there are seven cervical vertebrae in most species (the exceptions are dugongs, manatees and sloths);

large relative sizes of the brain, significant development of the cerebral cortex, high level development of the sense organs.

There are about 4.5-5 thousand species of mammals in the world, belonging to three subclasses and 21 orders, although some experts distinguish only 18 orders:

Subclass I - cloacal (oviparous or first animals) with one detachment - single pass;

II subclass - marsupials with one detachment of marsupials;

Subclass III - placental (or higher animals) with nineteen orders: insectivores, bats, woolly-winged, semi-monkeys (lemurs), monkeys (primates), edentulous, lizards (pangolins), aardvarks, rodents, hares, carnivores, pinnipeds, cetaceans, artiodactyls , calluses, equine, hyraxes, proboscis (elephants), lilac (sea cows).

In a number of representatives of this class, the size and weight of the body vary within a very wide range. The smallest animal of the world fauna, the baby shrew, weighs only 1.2 g and reaches 45 mm in length, and the largest is the blue whale, about 150 tons and 33 m, respectively. The skin of animals is represented by the stratum corneum of the epidermis, the Malpighian layer, the corium (skin itself), and also a layer of connective tissue, which may contain (sometimes significant) fat accumulations. Animals of this class are characterized by a large number of horn formations, which include:

hair (characteristic of almost all mammals, except cetaceans), as well as their various modifications: whiskers or sensitive hair (for example, "whiskers" in cats), bristles (pigs), needles (hedgehogs, porcupines, echidnas);

scales (in pangolin lizards);

horny plates (armadillos);

horns in rhinos, horn covers in bovids (cows, goats);

nails (human and other primates);

claws (predators, anteaters);

hooves (horses, cows, tapirs, hippos).

Often the hairline is highly developed and forms thick fur. There are two types of hair:

Long and relatively sparsely spaced, called ostia;

Short and dense, called undercoat.

The skin is rich in glands, among which sebaceous and sweat glands are distinguished. The sebaceous glands have a groin-shaped body, from which channels extend, opening in the hair bag. These glands secrete an oily secret. Sweat glands look like tubes folded into a ball, opening on the surface of the body. The lactiferous and odorous glands are modified sweat glands. The mammary glands that secrete the milk necessary for feeding offspring have a vine-like structure and open on the nipples. In monotremes (platypus, echidna), these glands have a tubular structure and do not open on the nipples, since they do not exist, but into hair bags. Platypus and echidna cubs simply lick drops of milk from their mother's fur. The skeleton has a number of features. The surface of the vertebrae is flat, not saddle-shaped, as in birds, and not convex-concave, as in reptiles. The spinal column is divided into five sections:

Cervical (in the vast majority of cases it consists of 7 vertebrae);

Thoracic (numbers from 9 to 24, more often 12, vertebrae);

Lumbar (2-9 vertebrae);

Sacral (from 4 to 9, while true sacral vertebrae - 2);

Tail (contains from 3 to 49 free vertebrae).

The girdle of the forelimbs (shoulder) is represented by the shoulder blades and clavicles (absent, for example, in ungulates), the coracoid is reduced and fuses with the shoulder blade, forming the coracoid process. The free forelimb consists of: the humerus, ulna and radius, wrist, metacarpal bones and phalanges of the fingers. The belt of the hind limbs (pelvic) is represented by the pelvic bones (sciatic, pubic and ilium). The free hind limb consists of the femur, tibia, tibia, tarsus, metatarsal bones, and phalanges of the fingers.

The digestive system is represented by: the oral cavity, pharynx, esophagus, stomach and intestines. The intestines are divided into three sections:

small intestine;

colon;

rectum.

Brief description of the 16 most famous units:

Detachment single pass. Representatives: platypus, echidna and prochidna. They are characterized by a number of primitive features: the presence of a cloaca, the absence of nipples, the laying of eggs, significant fluctuations in body temperature, etc.

Order of marsupials. Representatives: kangaroo, marsupial devil, koala, wombat, etc. Characteristic: underdevelopment of the placenta, the presence of marsupial bones and a bag in which the cubs are born, the cubs are born underdeveloped.

Order of insectivores. Representatives: hedgehogs, shrews, moles, desman, etc. - the most primitive detachment of placental mammals.

Detachment woolly. Representative: woolly wing, living in South-East Asia. Characteristic features are similarities with insectivores, bats and primates. A membrane covered with hair is developed on the sides of the body.

Order of bats. Representatives: bats (evening, bats, horseshoe bats, vampires, etc.) and fruit bats. The forelimbs are turned into wings: the fingers are elongated and a membrane is stretched between them.

Squad of lemurs. Representatives: loris, indri, tarsier, ring-tailed lemur, etc. Occupy an intermediate position between insectivores and primates.

A detachment of primates. Representatives: monkeys, spider monkeys, chimpanzees, gorillas, humans, etc. They are characterized by a significant development of the brain, a large number of furrows and convolutions of the cortex.

Squad of rodents. Representatives: rats, mice, porcupines, squirrels, marmots, nutria and many others. The most numerous group. Animals belonging to this order are characterized by a significant development of incisors (2 each on the upper and lower jaws), there are no fangs.

Detachment hare. Representatives: hares, pikas, rabbits. On the upper jaw there are not two incisors, as in rodents, but four.

Squad of carnivores. Representatives: cats, lions, leopards, mongooses, martens, wolves, dogs, hyenas, bears, raccoons. They have poorly developed incisors, powerful fangs and molars with sharp cutting surfaces.

Detachment pinnipeds. Representatives: seals, fur seals, walruses, ringed seals, etc. Characterized by: valky massive body, modified flippers fore and hind limbs. The teeth are usually conical in shape.

Order of cetaceans. Representatives: baleen whales (blue, bowhead whale, humpback, fin whale, etc.) - teeth are laid at the embryos, but do not develop in adult animals, a horn formation hangs into the mouth - a whalebone; toothed whales (dolphins, sperm whales, killer whales, etc.) have well-developed more or less uniform conical teeth. In all whales, the forelimbs are transformed into fins, and the hind limbs are reduced. A horizontal caudal fin is developed, as well as a dorsal fin.

Detachment artiodactyls. Representatives: pigs, hippos, bulls, giraffes, antelopes, deer, goats, sheep, etc. The greatest development of only two fingers on each foot is characteristic.

Detachment callosities. Representatives: camels, llamas. They have claw-like hooves, two-toed limbs (they used to be classified as artiodactyls).

Detachment equids. Representatives: horses, tapirs, rhinos, donkeys, etc. They are characterized by the fact that only one toe on each foot (or an unpaired number) is most developed.

Proboscis squad (elephants). Representatives: Indian and African elephants. They are characterized by a significant development of incisors (tusks), only four molars (two each on the upper and lower jaws), have a trunk, which is formed as a result of fusion of the nose and upper lip.

Chordates are animals with a high organization and a developed nervous system. Chordates are fast in movement, can easily get their own food, quickly adapt to a changing environment. About 40 thousand species of Chordates inhabit our planet.

There are representatives of Chordates of small size (ascidians), and large individuals (blue whale weighing up to 160 tons), live in water bodies, air, on the expanse of land, in the depths of the soil. They are diverse, but they are characterized by common properties.

Chordates have internal skeleton- chord. This is a support structure that stretches along the body like an elastic cord, is formed from the endoderm. It is present in the embryonic stage in all representatives. In the process of development, in highly developed Chordates it is replaced by inert tissue, forming the spine, in the lower ones it remains for the entire period of existence.

Nervous system Chordate animals are represented by the neural tube, which is located near the chord, inside there is a band formation - a neurocele. The anterior part of higher animals is transformed into hemispheres.

Bilateral symmetry(mirror reflection internal organs) evolved as an adaptation to surface crawling in actively moving individuals.

Visceral fissures located in the pharynx in the form of two holes. In the embryonic period, gills are located on their walls, which are preserved in lower animals; in other representatives they do not function.

Origin of Chordates

To this day, it has not been possible to form a single point of view on the origin of the Chordates. This question was asked by scientists in the 19th century. It was assumed that their ancestors may have been arthropods, but soon this hypothesis was refuted, due to significant differences between them in the embryonic period.

Next hypothesis: the origin of the Chordata from the coelenterates(due to the presence of gill slits, stomochord). Over time, it turned out that they have more differences than similarities. Modern biologists still cannot solve this problem.

A group of deuterostomes is distinguished, which have a number of similar features with Chordates:

• The structure of the digestive system;
• nervous system;
• circulatory system.

It is assumed that the predecessors of the Chordates were free-swimming animals, which were divided into inactive individuals Lancelet and Shell, and another branch gave Vertebrates, which actively began to develop. The sides of the body of vertebrates have made a coup: the transition from the ventral to the dorsal side. It is believed that this event became a key event in their further evolution.

Systematics of Chordates

The phylum Chordata is divided into three subtypes.

Subtype Tunicates (larval chordates) has about 1000 species that have a chord only in the initial stages of development.

Ascidian class leads a sedentary lifestyle, they cling to stones at the bottom of the sea, or to the base of ships, forming continuous layers of small individuals. Ascidians have openings: the mouth serves as a filter for trapped water, the filtered food enters the intestines and then the products of digestion are excreted through the anus.

Salps and Appendiculars able to move freely in the water.

Tunicates are hermaphrodites(both testes and ovaries are present), larvae emerge from the eggs, which bear little resemblance to an adult, have signs of an internal skeleton, which indicates a relationship with vertebrates.

Subtype Cranial- marine inhabitants of the near-bottom territory, retained the signs of typical chordates (neural tube, gills, notochord). The brain is not developed, they lead a primitive way of existence, reaching a maximum size of 7 cm, representatives are dioecious individuals, spawn, live in the sands at the bottom of the sea depths and oceans, leaving only a part of the body with an oral cavity outside for food. Allocate one Class Lancelets.

Subtype Vertebrates- highly organized individuals, with the presence of developed hemispheres of the brain and cranium, the spinal column, which serves as a protective sheath for the spinal cord. In the process of evolution, they received a complex morphological structure, improved sense organs, switched from a sedentary lifestyle, began to easily move across the expanses of earth, air and water. Vertebrates include amphibians, fish, birds, reptiles, mammals and cyclostomes.

Classification of Chordates - scheme

Features of the structure of chordates

What features of the structure were formed in chordates in the process of evolution?

Skin in non-cranial they consist of a single-layer epithelium, in vertebrates it is fluff, feathers, scales, and also from derivatives of the epidermis - claws, horns, hooves. There are glands that secrete sweat, sebum, odorous substances. For example, in cows, goats, sheep, mammary glands are formed to feed offspring.

Phylogenesis circulatory system chordates comes from the mesoderm, a circle of blood circulation is formed (closed), the heart is in the abdominal region, the dorsal and abdominal arteries, which are connected by anastomoses. The walls of blood vessels are expelled by endothelial cells, which helps to maintain homeostasis, the amount of blood glucose and proteins has increased (rudiments of immunity).

Nervous system in the embryonic period, it looks like a layer of thickened ectoderm, its endings are closed and form a neural tube. The phylogenesis of the brain of chordates comes from the anterior end of the neural tube, the dorsal from the posterior. The formation of the brain (cephalization) has become a necessary condition for the evolutionary development of Chordates. They began to distinguish external stimuli, to perceive the world around them with the help of their senses. Higher chordates have a brain with five divisions, which were formed from three cerebral vesicles.

The development of the respiratory system and the digestive system is closely connected; there is a common laying under the guise of a straight tube, which in higher chordates is differentiated into two independent systems.

In the lower chordates digestive tract has no departments, in lancelets, the mouth opening with many tentacles communicates with the pharynx, where the filtering apparatus is located, then the food is then sent through the posterior groove to the intestine and excreted by the anus, the glands are not developed. In vertebrates, the digestive system already consists of separate structures: the pharynx, esophagus, gastrointestinal tract, secreting glands appear: the liver and pancreas.

Breath carried out by gills and lungs (terrestrial vertebrates). After leaving the water, amphibians have formed lungs, but functionality they are insufficient, so additional gas exchange is carried out through the skin. Thus, for the Class Amphibians, skin-pulmonary respiration is characteristic.

The class Birds is characterized by the presence of double breathing.. The respiratory apparatus consists of the larynx, trachea, bronchi, lungs with air sacs. During the flight, birds use air sacs for gas exchange, the inhaled air passes through the lungs twice - both on inhalation and on exhalation - this is the mechanism of double breathing.

breeding system in chordates, it is represented by testes and vas deferens in males, ovaries and oviducts in females. Chordates, with the exception of larval-chordates, are dioecious.

Lecture: chordate animals. Characteristics of the main classes

chordate animals

Evolutionarily, this taxon is the youngest. Today there are 60 thousand species.

Distinctive features of their structure and metabolism are:

1. The presence of an elastic rod-chord or a full-fledged spine;

2. The neural tube is located on the dorsal side of the body, forming the spinal cord;

3. Developed brain;

4. Oxygen respiration;

5. The intestine does not enter the tail section.

Among the chordates there are marine inhabitants, as well as species living on land, in the soil, in the air.

lancelets

These are marine animals of a primitive structure. Many scientists consider them as a transitional group from invertebrates to vertebrates.

The structural features of this animal are:

thin chord;

the presence of gills;

located in the dorsal part of the body neural tube.

The lancelet has a translucent body, on the back and ventral side, as well as the end of the tail, there are fins, the main function of which is movement and maintaining balance in the water. The skin is thin, one-layer. The central nervous system is represented by a single tube. There is no differentiation between spinal cord and brain. The tentacles located around the mouth are used as sensory organs. There are simply arranged light-sensitive eyes. The skeleton is represented by a chord, along which are strands of muscles.

The pharynx can occupy up to a third of the length of the body, and gill slits are also located in it. The intestine is primitive, undifferentiated, ending in an anus. There is a hepatic outgrowth that secretes enzymes. The excretory system is similar to that of annelids - a system of convoluted tubules, metabolic products are excreted through the gills. The lancelet breathes the entire surface of the body. The circulatory system is developed, partially closed, there are vessels. Lancelets are dioecious, fertilization is external. The eggs develop in an aquatic environment.

Fish

A characteristic feature is the presence of developed jaws and gill breathing. The outer covers are leather. In bony it is covered with scales, in cartilaginous it is naked, with rows of plaques. They can move with the help of fins.

The spinal cord is located inside the spine. There are ribs. The brain consists of five sections. Along the body is the organ of tactile senses - the lateral line. Eyes of complex structure. There are organs of taste and smell. The organs of hearing are paired. Most representatives have a single circle of blood circulation and a two-chambered heart.

Fish grab food with their mouths, tear them apart and hold them with their teeth. The lump enters the throat, then through the esophagus into the stomach. The anal opening is located in the region of the posterior pelvic fins. The body of the fish maintains its osmotic pressure by excreting excess salts by the kidneys.

Fish are bisexual for the most part, hermaphrodites are rare, some of them are capable of self-fertilization. Mating behavior is quite complex - nests are built where eggs are laid. Fertilization is external.

Amphibians

This is a relatively small taxon of animals adapted to living on land and in water. For reproduction, most species require a reservoir, since in the larval stage the amphibian lives in the aquatic environment.

The skin is thin and smooth, it is easily permeable to gases and liquids, and is equipped with a huge number of capillaries for additional gas exchange. It contains many mucus-producing glands. The skeleton has a complex structure, divided into the spine, skull and limbs. The muscle system has a rather complex structure, providing mobility. Respiratory organs are gills, lungs and skin.

The circulatory system consists of two circles of blood circulation, the heart is three-chambered (two atria and one ventricle). Metabolic rate is low, animals are completely dependent on temperature external environment are cold-blooded. All amphibians are predators. The trapping organ is long tongue. The intestines are divided into sections and open into the cloaca. The excretory system is represented by the kidneys and the bladder, which has an outlet to the cloaca. Some substances are removed through the skin.

The brain is larger than that of fish, there are nerve plexuses in the area of ​​​​the shoulders and lower back. The eyes are adapted to the atmospheric environment, equipped with eyelids. There are two olfactory sacs. The hearing aid is quite complex structure, there is a tympanic membrane and a middle ear. The skin contains many nerve endings and is the organ of touch.

All species have separate sexes, fertilization is external. The development is complex, stage by stage - egg, larva, metamorphosis, adult. Eggs are laid in water by most species.

reptiles

In this taxon, mainly terrestrial species are represented, the distinctive features of which are:

dry skin covered with scales or scutes;

more pronounced division of the spine into sections. The head can turn;

all but snakes have a chest, there are intercostal muscles that provide breathing.

The developed nervous system, the brain consists of 5 departments. There are 6 sense organs. Breathing is pulmonary. The heart is three-chambered, a partial septum appears in it, separating venous and arterial blood. A more complex gastrointestinal tract, where differentiation into departments is more pronounced. Excretory system in the form of kidneys, bladder and cloaca. Reproduction is bisexual, with internal fertilization. The embryo develops in an egg equipped with a leathery or calcareous shell. Some species have live birth. The development is direct. There is care for offspring.

Birds

This is a class of egg-laying warm-blooded animals adapted to flight in the atmosphere. In connection with this, there were qualitative changes body structure:

forelimbs in the form of wings;

lightweight skeleton, the presence of a pectoral keel and powerful muscles;

the presence of a feather cover;

powerful respiratory system consisting of lungs and five pairs of air sacs;

streamlined body shape;

the presence of a beak;

four-chambered heart;

there are no teeth, food is crushed in the stomach, for which the bird swallows sand and pebbles;

fast metabolism.

A very developed brain with a large cerebellum that controls body position and motor activity. Complex intellectual behavior.

Reproduction is bisexual, fertilization is internal. The embryo develops in the egg. Most species are monogamous. Marriage behavior is complex.

Birds are important contributors to ecosystems. They contribute to the spread of plants by spreading seeds, predators regulate the number of small animals.

mammals

The most evolutionarily young and progressive taxon. It has a number of fundamental differences from all other animals:

Live birth (except for the first animals) and feeding offspring with milk;

Real warm-bloodedness;

Strong development of sebaceous and sweat glands;

Division of the internal cavity of the body into two by a diaphragm;

High development of the nervous system;

differentiated teeth.

Representatives of this class are capable of higher nervous activity, an active lifestyle.