Type Chordata. Typical characters of Chordata. Chordata animals - general characteristics of the type and examples of animals 1 what are the general characteristics of the chordate type

What are the general characteristics of the chordate phylum?

The main general characteristics of the chordate type:

*The body is bilaterally symmetrical.

*The intestine is through.

*Above the intestines there is a chord.

*Above the notochord, 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.

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Phylum Chordata. general characteristics

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 is transformed into the brain; in the trunk and caudal sections it is represented by the spinal cord,

3. The anterior section of the digestive tube - the pharynx - is penetrated by gill slits, through which it communicates with the external environment. In terrestrial animals, gaps are present only in the early period of embryonic development, while in aquatic chordates they remain throughout life.

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

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

Source: Good luck!

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. The main feature of the 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. In 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 different species of individuals, differing 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:

1. The location of the neural tube above the axial skeleton and the formation of the spinal cord from it.
2. The presence of a rod - a chord.
3. Absence of intestines in the caudal region.
4. 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 in the development of the historical animal world.

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:

1. The habitat of individuals of the first direction was hard ground. This contributed to the active development of the filtering apparatus, which 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.
2. 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.
3. 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. The top layer is 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.

The musculoskeletal system is presented in the form of a skeleton, consisting of a chord and connecting tissues 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.

The phylum Chordata unites animals that differ in appearance, living conditions, and lifestyle. Representatives of this type are found in all major environments of life: in water, on land, in the soil, in the air. They are distributed throughout the Earth. The number of species of modern representatives of chordates is about 40 thousand.

The phylum Chordata includes skullless, cyclostomes, fish, reptiles, amphibians, mammals and birds. Tunicates can also be classified as this type - this is a unique group of organisms that lives on the ocean floor and leads an attached lifestyle. Sometimes gastrobreathers, which have some characteristics of this type, are included in the phylum Chordata.

Characteristics of the type Chordata

Despite the great diversity of organisms, they all have a number of common structural and developmental features.

The structure of chordates is as follows: all these animals have an axial skeleton, which first appears in the form of a notochord or dorsal string. The notochord is a special non-segmented and elastic cord that embryonically develops from the dorsal wall of the embryonic intestine. The origin of the chord is endothermal.

Further, this cord can develop differently, depending on the organism. It remains throughout life only in lower chordates. In most higher animals, the notochord is reduced, and in its place a vertebral column is formed. That is, in higher organisms, the notochord is an embryonic organ that is replaced by vertebrae.

Above the axial skeleton is the central nervous system, which is represented by a hollow tube. The cavity of this tube is called a neurocoel. Almost all chordates are characterized by a tubular structure of the central nervous system.

In most chordate organisms, the anterior section of the tube grows to form the brain.

The pharyngeal section (anterior) of the digestive tube comes out at two opposite ends. The openings that emerge are called visceral fissures. Lower organisms of the type have gills on them.

In addition to the three above-mentioned features of chordates, it can also be noted that these organisms have a secondary mouth, like echinoderms. The body cavity in animals of this type is secondary. Chordata are also characterized by bilateral body symmetry.

The phylum Chordata is divided into subtypes:

• Skullless;
• Tunicates;
• Vertebrates.

Subtype Skullless

This subphylum includes only one class - Cephalochordates, and one order - Lancelets.

The main difference between this subtype is that these are the most primitive organisms, and all of them are exclusively marine animals. They are widespread in the warm waters of oceans and seas of temperate and subtropical latitudes. Lancelets and epigonychites live in shallow water, mainly burying the back part of their body in the bottom substrate. They prefer sandy soil.

This type of organism feeds on detritus, diatoms or zooplankton. They always breed in the warm season. Fertilization is external.

The lancelet is a favorite object of study, because all the characteristics of chordates are preserved for life, which allows us to understand the principles of the formation of chordates and vertebrates.

Subtype Tunicates

The subtype includes 3 classes:

• Salps;
• Ascidians;
• Appendiculars.

All animals of the subtype are exclusively marine.

The main difference between these chordates is that almost all organisms lack a notochord and a neural tube as adults. In the larval state, all the characteristics of the type in tunicates are clearly expressed.

Tunicates live in colonies or solitarily, attached to the bottom. There are significantly fewer free-swimming species. This subtype of animals lives in the warm waters of the tropics or subtropics. They can live both on the surface of the sea and deep in the ocean.

The body shape of adult tunicates is round, barrel-shaped. The organisms got their name due to the fact that their body is covered with a rough and thick shell - a tunic. The consistency of the tunic is cartilaginous or gelatinous; its main purpose is to protect the animal from predators.

Tunicates are hermaphrodites and can reproduce both sexually and asexually.

It is known that the ancestors of these organisms were free-swimming, but at present only tunicate larvae can move freely in the water.

Subphylum Vertebrates

Cranial animals are the highest subphylum. Compared to other subtypes, they have a higher level of organization, which is evident from their structure, both external and internal. Among vertebrates, there are no species that lead a fully attached lifestyle - they actively move in space, looking for food and shelter, and a pair for reproduction.

By moving, vertebrate organisms provide themselves with the opportunity to change their habitat depending on changing external conditions.

The above general biological features are directly related to the morphological and physiological organization of vertebrates.

The nervous system of cranial animals is more differentiated than that of lower animals of the same type. Vertebrates have a well-developed brain, which contributes to the functioning of higher nervous activity. It is higher nervous activity that is the basis of adaptive behavior. These animals have well-developed sensory organs, which are necessary for communication with the environment.

As a result of the emergence of sensory organs and the brain, a protective organ such as the skull developed. And instead of a chord, this subtype of animals has a spinal column, which serves as a support for the entire body and a case for the spinal cord.

All animals of the subtype have a movable jaw apparatus and an oral fissure, which develop from the anterior section of the intestinal tube.

The metabolism of this subtype is much more complex than that of all the animals discussed above. Cranial animals have a heart that provides rapid blood flow. Kidneys are necessary for removing waste products from the body.

The subtype Vertebrates appeared only in the Ordovician-Silurian, but in the Jurassic period all currently known types and classes already existed.

The total number of modern species is slightly more than 40 thousand.

Classification of vertebrates

The phylum Chordata is very diverse. The classes existing in our time are not so numerous, but the number of species is enormous.

The cranial subtype can be divided into two groups, these are:

• Primary water organisms.
• Terrestrial organisms.

Primary water organisms

Proto-aquatic eggs are distinguished by the fact that they either have gills throughout their entire life or only in the larval stage, and during the development of the egg, embryonic membranes are not formed. This includes representatives of the following groups.

Section Agnathans

• Class Cyclostomes.

These are the most primitive cranial animals. They actively developed in the Silurian and Devonian; at present, their species diversity is not great.

Section Gastrostomata

Pisces superclass:

• Class Bony fish.
• Class Cartilaginous fish.

Superclass Quadrupeds:

• Class Amphibians.

These are the first animals to develop a jaw apparatus. This includes all known fish and amphibians. All of them actively move in water and on land, hunt and capture food with their mouths.

Terrestrial organisms

The group of terrestrial animals includes 3 classes:

• Birds.
• Reptiles.
• Mammals.

This group is characterized by the fact that in animals, during the development of the egg, embryonic membranes are formed. If the species lays eggs on the ground, the embryonic membranes protect the embryo from external influences.

All chordates of this group live mainly on land and have internal fertilization, which suggests that these organisms are more evolutionarily developed.

They lack gills at all stages of development.

Origin of chordates

There are several hypotheses for the origin of chordates. One of them suggests that this type of organisms originated from the larvae of intestinal-breathers. Most representatives of this class lead an attached lifestyle, but their larvae are mobile. Examining the structure of the larvae, one can see the rudiments of the notochord, the neural tube and other features of chordates.

Another theory states that the phylum Chordates evolved from the crawling, worm-like ancestors of the gastrobreathers. They had the rudiments of a chord, and in the pharynx, next to the gill slits, there was an endostyle - an organ that contributed to the secretion of mucus and the capture of food from the water column.

The article discussed the general characteristics of the type. Chordates are united by many similar features of all organisms, but still each class and each species has individual characteristics.

Table of contents of the topic "Arthropods. Chordata.":

Systematics and characteristic features Chordata type are summarized below. Main distinctive feature chordates- this is the presence of a longitudinal dorsal cord - a notochord, which is located between the dorsal neural tube and the intestine. Chord serves as an internal support for the body and enhances the animal’s locomotor abilities. Chordata, probably evolved from the swimming larval forms of their ancient ancestors. In a form somewhat reminiscent of its original form, the notochord is present in some groups of invertebrate chordates that have survived to this day. However, in the process of evolution most chordates it has largely been replaced by bony vertebrae forming the vertebral column, or spine. Animals with a spinal column are called vertebrates, all others are called invertebrates.

Characteristic characters of chordates:
- At a certain stage of development there is a notochord. This is an elastic rod consisting of tightly adjacent
- vacuolated cells and covered with a durable membrane
- Three-layer coelomic animals
- Bilateral symmetry
- There are gill (visceral) slits (openings in the pharynx)* or arches
- The hollow neural tube is located dorsally
- Muscle blocks (myotomes) are located segmentally and are localized on the sides of the body
- Postanal tail (the beginning of the tail is located behind the anus)*
- Limbs are formed from more than one body segment*

Characteristic vertebrate traits:
- In adults, the notochord is replaced by the vertebral column - the spine (a series of vertebrae consisting of bone or cartilage)
- There is a well-developed central nervous system, including the brain/protected by the skull
- Internal skeleton
- Gill slits are few
- Two pairs of fins or limbs. They are connected to the rest of the skeleton via the pelvic and shoulder girdles."