The name of the organs of an insect. The internal and external structure of insects

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insect body

The body of an insect consists of three parts: head, chest and back. On the head, 6 segments have merged into one and are not at all noticeable. The chest consists of 3 segments. The back part is usually of 10, on the sides of which there are breathing holes.

insect skeleton

Insects are invertebrate animals, therefore the structure of their body is fundamentally different from the structure of the body of vertebrate animals, which include humans. Our body is supported by a skeleton consisting of the spine, ribs, bones of the upper and lower extremities. Muscles are attached to this internal skeleton, with which the body can move.

Insects have an external rather than an internal skeleton. Muscles are attached to it from the inside. A dense shell, the so-called cuticle, covers the entire body of the insect, including the head, legs, antennae and eyes. Movable joints connect numerous plates, segments and tubes that are present in the body of an insect. The cuticle is chemically similar to cellulose. Protein gives extra strength. Fats and wax are part of the surface of the shell of the body. Therefore, the insect shell is strong, despite the lightness. It is water and air tight. A soft film forms on the joints. However, such a strong body shell has a significant drawback: it does not grow with the body. Therefore, insects have to periodically shed their shell. During life, the insect changes many shells. Some of them, such as silverfish, do this more than 20 times. The insect shell is insensitive to touch, heat and cold. But it has holes through which, with the help of special antennae and hairs, insects determine the temperature, smells and other characteristics of the environment.

The structure of the legs of insects

Beetles, cockroaches and ants run very fast. Bees and bumblebees use their paws to collect pollen in "baskets" located on their hind legs. Praying mantises use their front paws to hunt, pinching their prey with them. Grasshoppers and fleas, escaping from the enemy or looking for a new host, make powerful jumps. Water beetles and bed bugs use their legs for paddling. Medvedka digs holes in the ground with its wide front paws.

Despite the fact that the legs of various insects look different, they have a similar structure. The paw in the basin joins the thoracic segments. Then come the trochanter, thigh and tibia. The foot is divided into several parts. At its end is usually a claw.

body parts of insects

hairs- microscopic sense organs protruding from the cuticle, with the help of which insects come into contact with the outside world - they smell, taste, hear.

Ganglion- a nodular accumulation of nerve cells responsible for the activity of individual parts of the body.

Larva- an early stage of insect development following the egg stage. Larvae options: caterpillar, worm, nymph.

Malpighian vessels- excretory organs of an insect in the form of thin tubes that go into the intestine between its middle section and the rectum.

pollinator An animal that carries pollen from one flower to another of the same species.

oral apparatus- specially designed to bite, prick or lick, organs on the head of an insect with which they take food, taste, crush and absorb it.

Segment- one of several components of the body of an insect. The head consists of 6 almost merged segments, the chest - of 3, the back - usually of 10 well-defined segments.

Shell change- a repeatedly repeated process in the life of an insect; it sheds the old shell in order to grow. In place of the old shell, a new one gradually forms.

tendrils- filamentous antennae on the head of an insect. They perform the functions of the sense organs and serve to obtain olfactory, gustatory, tactile and even auditory sensations.

compound eye- the compound eye of an insect, consisting of individual eyes, the number of which can reach several thousand.

Proboscis- the mouthparts of piercing-sucking or licking-sucking insects, such as bugs, mosquitoes, flies, butterflies and bees.

Exuvia- the old shell of an insect, which it sheds when it hatches.

Despite the huge variety, all insects have a common external structure, which is characterized by three invariable signs:

1. notch on the outer surface. The outer cover consists of cuticles - a very strong shell that forms an exoskeleton, consisting of separate segments or segments, which ensures mobility. Each segment is covered with chitin shields.
2. Three sections of the body of insects. The external structure of the body consists of segments. There can be up to twenty of them, and they are combined into departments, which are: the head, abdomen, and also the chest. The head consists of five or six segments, the chest includes only three, and the abdomen can include up to twelve segments. As a result of evolution, the number of segments has decreased and does not exceed fourteen. On the head is a mouth, eyes and a pair of antennae. The thoracic part contains limbs and wings, usually two pairs, and the abdominal part contains various appendages. Segments of the abdominal part, except for the last two, contain spiracles. In different insects, the body size can be from fractions of a millimeter to 30 cm in length.
3. The number of legs is the same. Despite the diversity of insects, all species contain three pairs of limbs, the base of which has two long segments: the thigh and lower leg. At the end of the leg is a jointed tarsus, on the terminal segment of which there is a pair of claws. They help insects move along an inclined surface and along the lower surface of various objects. Sometimes there are suction cups between the claws to facilitate movement on smooth or slippery surfaces.

The internal structure of representatives of the class of insects consists of the following systems:

• Respiratory. Oxygen, as well as carbon dioxide, is transported through the tracheal system, they open outward with spiracles. Most insects have an open tracheal system;
• Circulatory. Blood carries nutrients and has a protective function. It does not participate in the transfer of carbon dioxide and oxygen;
• Nervous. It consists of the peripharyngeal nerve ring, the ventral nerve cord and the brain, which are formed as a result of the fusion of nerve nodes;
• excretory. Maintains biochemical constancy within the body, and also monitors the ionic composition of the blood. Excretions are substances that are removed from the body, and the process itself is called excretion;
• Sexual. Well developed and located on the belly. Insects are dioecious animals. Their sex glands are paired. Fertilization is internal.

insect head

The cranium is strongly compacted. It consists of several merged segments. In different insects, their number ranges from 5 to 8 pieces. On the head are 2 eyes that have a complex structure, and from 1 to 3 simple eyes or eyes, as well as mobile appendages, which are antennae and mouth organs. The outer surface of the head is divided into sections, between which there are sometimes seams:

• the forehead is between the eyes;
• the crown is located above the forehead;
• cheeks are placed under the eyes from the side;
• the occiput follows the crown;
• upper lip borders on clypeus;
• there is a clypeus downward from the forehead;
• the upper jaws adjoin from below to the cheeks.

According to the external structure, the head of insects can be of the following shape: round (in a fly), elongated (in weevils) and laterally compressed (in grasshoppers), and its setting depends on which species it belongs to.

organs of vision

A pair of compound eyes is located on the sides of the insect's head and consists of several hundred, and sometimes thousands of facets. This is precisely due to the fact that the organs of vision of some insects, for example, dragonflies, occupy almost the entire head. Most adult insects and larvae have such eyes.

Between the compound eyes are ocelli or simple eyes, their number is usually three. One of them, having a triangular shape, is located on the forehead, and the other two are on the crown of the head. In some cases, only two side ones remain, and the middle one disappears. It happens and vice versa, there is only a triangular eye, and there are no side pairs.

tendrils

Otherwise they are called antennas. They are organs of smell and touch. A pair of antennae is located on the lateral parts of the forehead and is located in the antennal fossae. Each antennae has a thickened base of the segment, a stalk, and a flagellum.

In different species and groups of insects, the external structure of the antennae is different. They just determine the insect. Males and females of the same species may have a slightly different structure of these organs.

Mouth organs

Their structure depends on the food that insects eat. Those who eat solid food crush it with two mandibles. And sucking nectar, juice and blood, instead of chewing, have a proboscis, which can be needle-shaped in mosquitoes, thick in flies, long and crowded in butterflies.

From above and below, the oral organs are obscured by plates, which are lips - upper and lower. Some insects (gnawing-sucking or gnawing-licking) have both a proboscis and a mandible. The needle-like apparatus will be called piercing-sucking if the insect pierces the skin before sucking. Mouth organs in some species may not be fully developed.

Wings

Breast

In external structure, the chest of insects consists of three segments: anterior, middle, posterior. Each of which is located a pair of limbs. In flying insects, these are wings that are located on the middle and rear segments. Depending on the lifestyle, the following limbs are distinguished:

• digging;
• grasping;
• walking;
• swimming;
• jumping;
• running.

Abdomen

The body is made up of segments. Their number can vary from eleven to four. Lower insects have paired limbs, while in higher insects they are modified into an ovipositor or other organs. In adults, the number of body segments can be no more than three. This is due to the fact that some of them merge with each other, and the rest become a copulatory organ. Nevertheless, in most cases, five to eight segments are clearly visible, they separate the lower and upper parts.

They are interconnected by a thin membrane, which allows the abdomen to increase during the maturation of eggs or overflow of the intestines with food. In most insects, the external structure of the body is cylindrical or convex at the top and almost flat at the bottom. In addition, the belly can be flat, round, triangular in cross section and club-shaped. For example, in ants, the body is connected to the chest with the help of a small stalk, consisting of two segments, in wasps and bees - with a narrow constriction. Most primitive insects have two jointed appendages at the end of the body.

Cover (shell)

The entire body of insects, like other arthropods, is enclosed in a strong outer shell, the skeleton of which consists of chitin. It is a soft and brittle material in its purest form. In insects, on the top layer it is covered with a protein substance called sclerotin, it is this element that gives the necessary strength and rigidity to the skeleton. The top layer consists of wax-like substances that do not allow water to pass through.

Therefore, the external skeleton thoroughly protects the internal organs, keeps them from drying out, and also increases the hardness of the entire body. The secret of the strength of the cover of insects lies in their structure - a tube with a soft core is three times stronger than the same tube with a rigid rod, which is present in all vertebrates. But if the tube is made very thick, then it will lose its advantages, since the strength of a hollow cylinder decreases significantly with an increase in its diameter, which in turn limits the thickening of the body, and hence the size of invertebrate arthropods.

Biology. Insect class

The main adaptations that ensure the rapid development of insects:

• The ability to fly allows them to quickly explore new places and overcome various obstacles. Mobility is provided by well-developed muscles and jointed limbs.
• The chitinized cuticle, which consists of several layers, refers to the features of the external structure of insects. It contains special elements that protect the body from moisture loss, mechanical damage, as well as the influence of ultraviolet radiation.
• Small size contributes to survival and creates the conditions that are required for life even in small spaces, for example, in a crack in the bark of trees.
• High fertility. The average number of eggs that insects lay is two hundred to three hundred pieces.

Insects are found literally everywhere: in the garden, forest, field, garden, soil, water, on the body of animals. Examples of insects:

• the cabbage butterfly lives in the garden, in the field and in places where cabbage grows;
• the Maybug can be found in gardens and forests;
• The housefly lives near human dwellings.

The huge variety of habitats in the terrestrial environment has contributed to their speciation and wide distribution.

Insects are our constant companions in life. No matter how they sterilize the operating rooms, at least some fly will fly in, and even in houses they are always in large numbers ... For robotics engineers, insects are an inspiration, because only they can move on any surface, but repeating this in an artificial model is very complicated.

Like others, insects have an external (exo-) skeleton consisting of chitin. Outgrowths are often observed on the integument of the body - hairs, horn formations, scales, etc.

Body: head, thorax and abdomen separately. 3 pairs of walking legs. Most insects have wings(usually 2 pairs).

Features of the internal structure of insects

There are terrestrial insects, there are also aquatic representatives, so there are differences in respiratory system:

- in aquatic insects, breathing is carried out by the entire surface of the body;

- in terrestrial - respiratory organs - trachea.

Circulatory system: open circulatory system , insect blood is called hemolymph. The main vessel containing the hemolymph runs along the length of the insect in the dorsal part. The back of this vessel contains a "heart" - several pulsating chambers connected in series with each other.

Digestive system:

1. A very interesting oral apparatus - it is different for different species:

- gnawing- in those insects that eat solid food, or this food must be obtained (gnawed out);

- sucking (piercing-sucking) - for taking liquid food (butterflies and mosquitoes);

- muscoid (both gnawing and sucking like flies)

2. A system consisting of the stomach, intestines, rectum and anus.

excretory system:malpighian vessels(similar to arachnids).

Features of the structure of the nervous system of insects and sensory organs:

Insects have a very intense movement, and not chaotic, but quite purposeful, so such movement must be well coordinated. Insects already have a real nervous system - ganglion, consisting of three departments - the nerve node, the ventral nerve cord and a network of neurons throughout the body.

- antennae (antennas) - organs of touch;

- eyes - can be faceted (complex) and simple, but then there should be several of them.

- insects perceive and distinguish smells well (they have the basis of communication - the isolation and recognition of various chemicals).

reproductive system:

Insects are dioecious. Fertilization is mostly internal.

Development takes place as

Insects are very closely related to many other organisms on Earth.

For them - irreplaceable pollinators, for animals - food.

112. Look at the picture. Sign the name of the body parts of the beetle, indicated by numbers.

1. Mouth apparatus (head)

3. Prothorax

4. Elytra

113. Describe the class Insects.

Insects are a class of invertebrate arthropods, there are 1.5 million species of them.

The body is covered with a chitinous cuticle, which forms an exoskeleton, and consists of three sections: head, thorax, and abdomen.

Habitat: ground-air, water, soil, organism.

Body length - from mm to 15 cm.

Structure: a pair of antennae on the head, mouth organs (lower, upper jaws; lower lip), a pair of compound eyes. Chest - two pairs of wings (one pair - on the prothorax, the second - on the metathorax), three pairs of walking limbs. Wings - folds of chitinous cover. The abdomen has no limbs.

Sense organs: touch, smell - antennae; taste - palps of the lower lip and lower jaw; vision - simple and compound eyes.

114. Look at the pictures. Write down the similarities and differences between the animals depicted.

Similarity: they belong to the same type Arthropods, therefore they have an external skeleton formed by a chitinous cuticle and a segmented body with paired jointed limbs.

Differences: a crab (Crustaceans) has five pairs of limbs, a spider (Arachnids) has four, a bumblebee (Insects) has three. A spider and a crab have a cephalothorax and an abdomen; a bumblebee has a head, thorax, and abdomen. The bumblebee has wings. The respiratory system differs (gills, lung sacs, tracheas). The way of life and habitats also differ.

115. In the picture, color the systems of the internal organs of the insect with colored pencils and write the names of the organs that make them up.

Nervous system: peripharyngeal nerve ring, supraesophageal ganglion and ventral nerve cord.

Digestive system: mouth, pharynx, esophagus, stomach, middle and hind intestines, anus. There are salivary glands.

Circulatory system: heart, blood vessels.

Reproductive system: in males - testes, vas deferens, ejaculatory canal; in females - ovaries, oviducts, vagina.

Excretory system: Malpighian vessels.

116. Look at the picture. Sign the names of the organs of the insect, indicated by numbers.

1 - antennas

2 - peripharyngeal nerve ring

3 - thoracic ganglion

4 - trachea

5 - ovary

6 - Malpighian vessels

7 - middle intestine

8 - stomach

9 - esophagus

117. Fill in the table.

INSECT BODY SYSTEMS.

Insect organ systems	Organs	Functions
body integuments	chitinized cuticle, inner layer of cells	protective, attachment of muscles, regulation of water evaporation
body cavity	mixed - hemocoel	contains an open circulatory system
muscular	muscle bundles	motion
nervous	peripharyngeal nerve ring, supraesophageal ganglion and ventral nerve cord	regulation of vital activity, unification of the body into a single whole
sense organs	sensitive receptor cells	relationship with the environment
circulatory	heart, blood vessels	blood circulation, nutrient transport
Respiratory	trachea	gas exchange
digestive	mouth, pharynx, esophagus, stomach, middle and posterior intestines, anus. Has salivary glands	digestion
excretory	malpighian vessels	excretion of metabolic products from the body
Sexual	in males - testicles, vas deferens, ejaculatory canal; in females - ovaries, oviducts, vagina	procreation
Endocrine	glandular formations	release of substances to attract individuals of their own kind, to scare away enemies, to warn of danger

118. How does a butterfly develop?

Butterflies are insects with a full cycle of transformation. Between the larval stage (caterpillar) and the adult stage (butterfly) is the pupal stage. All development can be represented in the following way: egg - caterpillar - chrysalis - butterfly. Butterfly larvae are completely different from adults. At the pupal stage, a global restructuring of the whole organism occurs, with the formation of tissues and organs of an adult individual.

119. Name and characterize the types of development of insects.

1) Development with incomplete transformation. Three stages: egg-larva-adult insect (cockroaches, mayflies, dragonflies, praying mantises, lice, etc.). The eggs hatch into larvae that look like adults. they differ from adults in size, underdevelopment of the reproductive system and the absence of wings. The larvae grow, molt several times and gradually become like an adult. After that, the insect no longer grows.

2) Development with complete transformation. Four stages: egg-larva-pupa-adult insect (butterflies, wasps, flies, ants, etc.). The larvae are not at all like the adults. The body is usually worm-like; simple eyes or no eyes at all. The larvae grow and molt several times. Then the larva turns into a chrysalis, and their pupae are already an adult.

120. Using the picture, tell about the development of a grasshopper. What is this type of development called?

The grasshopper has development with incomplete transformation. They have juveniles that hatched from an egg, similar to an adult. With each molt, this similarity becomes more and more.

121. Fill in the table.

TYPES OF DEVELOPMENT OF INSECTS.

122. What is the importance of insects for humans?

Insects are of great importance in economic activity, as pollinators, increase the yield of cultivated plants.

The skin of insects has a complex, multilayered structure. First of all, they are divided into outer layer - cuticle and the inner layer skin cells - hypodermis. The substance that determines the basic properties of the cuticle is the nitrogenous polysaccharide chitin, which has high mechanical and chemical resistance.

Digestive system of insects

The digestive system is divided into three general sections: the anterior, middle, and hindgut.

The foregut includes the oral cavity, into which the salivary glands open, a pharynx with highly developed muscles, an elongated esophagus, a goiter - a reservoir for the accumulation of food, well developed in sucking insects, and a compact muscular stomach that grinds food, better developed in gnawing insects.

The main digestion occurs in the midgut under the action of secreted enzymes. The walls of the midgut absorb nutrients. In many insects, the midgut forms blindly closed processes that increase the digestive surface. In the thicker hindgut, excess water is absorbed with dissolved low molecular weight substances, excrement is formed, which is removed through the rectum and anus.

excretory system of insects

The main excretory organs of insects- Malpighian vessels, tubular tubules (from two to a hundred), the closed ends of which are freely located in the abdominal cavity, with the other ends they open into the intestine at the border of the middle and posterior intestines. Liquid metabolic products - excess salts, nitrogenous compounds - are selectively absorbed by the thin walls of blood vessels, concentrated and excreted through the hindgut.

Respiratory system of insects

It is represented by a complex of tracheas - air tubes with elastic walls containing chitin. Air enters the trachea through spiracles - small paired openings located on the sides of the segments, in many insects, from the mesothorax to the end of the abdomen. In the spiracles there are locking devices that regulate air exchange. Further, the trachea repeatedly branch up to the thinnest tracheoles, penetrating the entire body and delivering air directly to organs and tissues.

Insect circulatory system

The circulatory system of insects is not closed; part of its path, the blood passes not through special vessels, but in the body cavity. The central organ is the heart, or dorsal vessel, lying in the upper part of the abdominal cavity and subdivided into a series (6-7) of homogeneous pulsating chambers. The heart passes into the aorta, which, heading forward, opens into the cavity of the head. Further, the blood spreads into the body cavity due to the work of the heart and the contraction of the diaphragms, entering the vessels of the limbs, antennae and wings. Blood is sucked into the chambers of the heart through openings in the side walls. The blood of insects is called hemolymph.. It is usually unstained and does not contain hemoglobin or similar oxygen scavengers delivered directly by the tracheal system. The hemolymph performs the transport of nutrients and excretions, as well as the function of immunity.

Nervous system of insects

The central nervous system is represented by the supraesophageal nerve ganglion, or the brain, consisting of three pairs of fused nerve nodes. A near-pharyngeal nerve ring departs from it, connected below with a pair of subpharyngeal ganglia. From them in the lower part of the body cavity stretches the abdominal nerve chain. Initially paired nodes in each segment in some insects merge in the thoracic region. The peripheral nervous system is connected with the central nervous system - a set of nerves extending from the nodes to the muscles, and the sympathetic system that goes from the subpharyngeal nodes to the internal organs.

Sense organs of insects

Despite their small size, insects have complex, highly sensitive sense organs. The organs of vision are represented by complex compound eyes and simple eyes. The compound eye consists of thousands of elementary visual units - ommatidia. Insects have developed color vision, the spectrum of which is somewhat shifted to the ultraviolet region. Simple eyes, apparently, serve as additional photosensitive organs and are able to perceive polarized light. Insects show a highly developed visual orientation, some of them are guided by the sun, taking into account its declination.

The main organs of smell are antennas that carry many special sensitive receptors. The sharpness and specificity of the sense of smell of insects is unusually great. The males of some moths find the female, guided by the smell of the sex pheromone, from a distance of 10-12 km.

Only some insects have specially developed hearing organs. Taste receptors are concentrated mainly on the oral appendages - sensitive palps, and in some insects (butterflies and bees) are found even on the paws. Insects have a highly specific taste, which makes it possible to accurately identify food objects.

In the skin of insects, in addition to numerous tactile receptors, some receptors register pressure, temperature, microvibrations of the environment, and other parameters.

reproductive system of insects

The reproductive system of insects is represented by the genital and adnexal glands, excretory ducts and external genital organs. The female reproductive system consists of paired glands - ovaries, consisting of egg tubes. They produce numerous eggs. The excretory ducts are paired oviducts coming from the ovaries, uniting into an unpaired oviduct, which opens with a genital opening. A chamber for storing sperm is connected to the oviduct - a seminal receptacle. In the male reproductive system, paired glands are developed - the testes, consisting of small lobules that produce spermatozoa. Paired spermatic ducts depart from them, uniting in the ejaculatory canal, passing through the copulatory organ of the male. Fertilization in insects is internal.