Class Insects. general characteristics

The body of insects consists of a head, thorax and abdomen. The only group of invertebrates that acquired the ability to fly.

From above and from the sides, the head is covered with a head capsule. On the sides of the head are two compound eyes, between which there are usually simple eyes.

The head has a pair of jointed antennae. The antennae contain tactile and olfactory receptors.

The mouth is located on the ventral side of the head and is surrounded by modified limbs that form the oral apparatus. Gnawing mouthparts have beetles, cockroaches, grasshoppers, butterfly caterpillars, etc. It is formed by the upper lip, upper jaw, lower jaw and lower lip. The tongue belongs to the oral apparatus.

The chest is formed by three segments. Three pairs of walking legs are attached to the segments of the thorax.

On the dorsal side of the second and third segments of the chest are wings - two-layer folds of the integument of the body. The trachea and nerves pass through the wing. Their occurrences form thickenings - veins. In beetles, cockroaches, the first pair of wings turns into hard elytra. In Diptera (flies, mosquitoes), only the first pair of wings is developed, and the second is turned into halteres - organs of stabilization during flight. Among insects, there are primarily wingless species that belong to ancient, primitive groups. There are secondarily wingless insects that have lost their wings due to lifestyle features, such as fleas, lice, etc.

The abdomen is made up of different number segments. There are no limbs on the abdomen, but their rudiments may be found: styli, cerci, ovipositors.

The mouth leads into the oral cavity, the ducts of several pairs of salivary glands flow into it. The oral cavity passes into the pharynx, behind which is the esophagus, sometimes expanding into a goiter. The stomach is muscular, the intestine ends with an anus. Insects do not have a liver.

Excretory organs - Malpighian vessels. The fat body takes part in the excretion. Modified areas of the fat body in some insects (firefly beetles) form organs of luminescence.

The nervous system is formed by the brain, the peripharyngeal nerve ring and the ventral nerve cord.

The ganglions of the thoracic segments are the most developed, since they innervate the legs and wings. The sense organs are complex and diverse, there are organs of touch, smell, taste, sight, and in some species - hearing.

Breathing is only tracheal. The tracheae begin with paired respiratory openings. Inside the body of an insect, the trachea branch and braid internal organs.

The circulatory system is relatively poorly developed. The heart is tubular and located on the dorsal side of the abdomen.

Insects have separate sexes, sexual dimorphism is pronounced. Sex glands are paired, located in the abdomen. Fertilization is internal.

The development of primitive insects proceeds without metamorphosis. In highly organized insects - development with metamorphosis (or with transformation). In the latter case, development can be with incomplete transformation and with complete transformation.

During development with incomplete transformation, the organism goes through the following stages: egg - larva - adult insect. The larva hatched from the egg resembles the adult insect in a number of important ways. Larvae and adult insects have a common body plan, the same type of mouth apparatus, and, consequently, a similar spectrum of nutrition, and usually live in the same environmental conditions. Larvae differ from adult insects in the underdevelopment of wings, an incomplete number of abdominal segments, and the absence of secondary sexual characteristics. With incomplete transformation, insects of the orders Orthoptera (grasshoppers), Cockroaches, Hemiptera (bugs), Homoptera (aphids), lice, etc. develop. In insects with complete transformation, development proceeds according to the following scheme: egg - larva - pupa - adult insect. Larvae fundamentally differ from adult insects in terms of the general plan of body structure, as a rule, have a different type of organization of the oral apparatus and a different spectrum of nutrition, and live in different environments (for example, a mosquito and its aquatic larvae). The larva after the last molt passes into a state of rest - it pupates. With complete transformation, insect orders develop: Coleoptera, Lepidoptera, Hymenoptera, Diptera, Fleas, etc.

1. Arthropods. General structure

This is the most numerous type of animal. It has three classes - crustaceans, arachnids and insects. Mastered all the environments of life. Unites more than 1.5 million species. Arthropods are the pinnacle of the invertebrate evolutionary branch. They began their development in the seas of the Cambrian period and became the first land animals capable of breathing atmospheric oxygen.

Arthropods are characterized by common features:

1. The body is covered with chitin - a horny substance, sometimes impregnated with lime. Chitin forms the outer skeleton and performs protective functions.

2. The limbs have an articulated structure, connected to the body through joints, each segment has one pair of legs.

3. The body is segmented and divided into two or three sections.

4. The muscles are well developed and attached in the form of muscle bundles to the chitinous cover.

5. The circulatory system is open, there is a heart. Blood - hemolymph pours into the body cavity and washes the internal organs.

6. There are respiratory organs - gills, trachea, lungs.

7. The nervous system of the nodal type is more perfect. There are complex compound eyes, antennae - organs of smell and touch, organs of hearing and balance.

8. The excretory system is more perfect than that of annelids.

9. Arthropods are mostly dioecious animals that reproduce by eggs.

2. Class crustaceans.

The class includes about 20 thousand species. It includes crayfish, crabs, lobsters, daphnia, cyclops, wood lice, shrimps and more. etc. Basically, these are inhabitants of the waters, and their respiratory organs are gills.

Consider the external structure crustaceans on the example of crayfish.

The body is divided into three sections: head, thorax and abdomen. Head and chestmerge to formcephalothorax,covered with a common shell; On the head are two pairs of antennae and three pairs of jaws. First couple -antennuleslocated on the head, and the second pair -antennas -on the first segment of the trunk (long). On the chest there are three pairs of mandibles and five walking legs, and the first pair of walking legs has powerful claws. On the abdomen, on each segment, there are also limbs - abdominal. The female holds the eggs with them.

Consider the internal structure.

Living in water, crayfish breathe through gills. They are located under the lateral edges of the cephalothoracic shield. The circulatory system is not closed, there is a heart. Crayfish feed on carrion, biting the body with claws; have a complex digestive system. The nervous system of crayfish is the same as that of all invertebrates. It is represented by the ventral nerve cord, the peripharyngeal nerve ring, consisting of the subesophageal and supraesophageal nerve nodes. Cancer has a well-developed sense of smell and touch, there is an organ of balance and stalked eyes, consisting of many simple eyes - facets, the number of which increases with age. Each eye sees only a part of the object, but as a whole an image is formed. This vision is called "mosaic vision".

crayfish segregated animals. After internal fertilization, the female lays eggs. Development comes frommetamorphosis -complex transformation. The larva molts several times in the process of growth, each time becoming more and more similar to the adult form.

According to their structure, crayfish can be divided into two groups: lower crayfish and higher crayfish.

The lower crustaceans include more primitive animals - daphnia and cyclops. They are pretty small creatures. They can be seen at low magnification of the microscope. Atdaphniathere are two-branched antennae, which are not only sense organs, but also organs of movement. Daphnia feed on bacteria, algae and other small organisms.

At cyclopshave a head. Powerful antennules (the first pair of antennae) serve as the main organ of locomotion. These small crustaceans (daphnia and cyclops) are food for fish and form zooplankton.

The higher crustaceans include:crayfish, crabs, lobsters, lobsters, shrimps.

At crabsfive pairs of legs extending from the powerful cephalothorax carapace are clearly visible. The abdomen is shortened, flat. Many crabs and shrimp are of commercial importance.

Unlike crabs, lobsters and lobsters have a long, well-developed abdomen. These crustaceans live in the seas and oceans and are also of commercial importance.

At hermit crabthe fleshy abdomen is covered only with a thin soft film. Therefore, he hides it in the empty shells of sea mollusks, which is why the body takes the form of a swirling cavity of the shell. When the cancer grows after molting, it changes the shell to a more spacious one.

Almost all crustaceans are edible and have almost the same taste.

3. Arachnids.

About 60 thousand species are known.

Consider the external structure of spiders.

The body is divided into sections: the cephalothorax and the abdomen are rounded. Four pairs of legs depart from the cephalothorax, i.e. 8 pieces with claws. The legs are equipped with tactile hairs. There are no antennae on the cephalothorax, but there are tentacles,which serve as organs of touch. There are jaws - chelicerae, which serve to grasp and tear food.

Internal building.

In connection with the terrestrial way of life, the lungs and trachea are developed.

The circulatory system, like all arthropods, is open. In the abdomen, the heart and blood vessels.

The nervous system is the same: the ventral nerve chain and the peripharyngeal nerve ring. Spiders have simple eyes, so their eyesight is poor. There are many tactile hairs on the body and limbs, to which nerve endings fit.

The upper jaws have sharp curved ends where the ducts open.venom glands. At the end of the abdomen there are arachnoid warts, to which ducts openspider glands. They produce a thick liquid, which, when leaving the body, solidifies into a thin transparent thread - a web. The web is a trapping net and serves to capture prey. The spider on the web approaches the entangled victim and pierces it with its upper jaws, injecting poison and digestive juices. The venom kills the prey, and the digestive enzymes begin to digest the prey. After a while, the spider sucks out the digested food. This type of digestion is called external.

The excretory organs are the Malpighian vessels - branching tubules that open into the intestines.

Separate sexes. They reproduce by eggs that are laid in a cocoon. The offspring are protected. The development of born spiders occurs gradually with numerous molts.

Most famouscross spiderwith a cruciform light spot on the back,house spider, silver spider, living in the water. The silver spider builds a “cocoon” from the web, which is filled with air, which the animal needs to breathe underwater.

In the southern regions, in Ukraine and the Caucasus, there is a large spidertarantula.He lives in a mink, which he pulls out in the ground, and the entrance to it is braided with cobwebs. Its bite is very painful.

A small black spider lives in the deserts and steppes in the south.karakurt(translated from Turkic means "black death"). The bite of this spider is extremely dangerous. The poison of the karakurt causes pain, convulsions, vomiting, and sometimes death. The bite of karakurt is fatal for camels and horses, but sheep calmly eat it along with grass.

Spiders are very useful animals that destroy many harmful insects. The venom of most spiders is not dangerous to humans.

Causing a lot of harmflour(barn), cheese, cereals And bulb mites. scabies mite (up to 0.3 mm ) gnaws numerous passages under the skin of a person, causing acute itching (scabies). The disease is contagious - transmitted by shaking hands.

taiga tick suffers from a severe viral disease - encephalitis. When bitten, the virus enters the bloodstream, reaches the brain, causing inflammation, and in severe cases, death can occur.

Ticks are carriers of such dangerous diseases.

Scorpions - these are the oldest arachnids, at first glance more like crustaceans. They are descendants of an ancient group of crustacean scorpions that became extinct about 190 million years ago. They have a jointed abdomen, the body is covered with a thick chitinous cover, and there are claws on the cephalothorax, very similar to crayfish claws. But upon closer examination, you can see that four pairs of legs depart from the cephalothorax, and the claws are a modified second pair of jaws. The posterior abdomen has a pair of venom glands with a sting. Scorpion, grabbing prey with claws, bends its abdomen over its head and stings the victim. Scorpions are poisonous, tropical species are of particular danger to humans. The stings of scorpions, which live in our Volga region and the Caucasus, are painful, but not fatal.

4. Class insects

The largest group among animals. It is believed that their number ranges from about 1.5 to 2 million. Insects have mastered all the environments of life: air, water, land, soil. Their evolution followed the path of adaptation to terrestrial existence.

Body structure.

The jointed body is covered with a chitinous cover, divided into three sections: the head, chest and abdomen. They have three pairs of jointed limbs. Most adults have wings. On the head there is one pair of antennae (antennae) and three pairs of mandibles, forming different types horn apparatus. The oral apparatus consists of one pair of lower and upper jaws, lower and upper lips.

According to the structure of the oral apparatus, insects can be divided into 4 groups:

licking or varnishing,organs have bumblebees, bees, wasps, feeding on liquid food - the nectar of flowers.

sucking organs characteristic of butterflies.

Piercing-sucking mouthparts have mosquitoes, bedbugs, aphids.

In connection with the different lifestyles, the limbs of insects are:

- running(cockroach),

- digging(bear),

- swimming(swimming beetle),

- jumping(Grasshopper).

Internal structure:

· The nervous system of insects is well developed. The sense organs have reached a high organization: touch, smell, taste, sight, hearing. Compound compound eyes are especially well developed (up to 28 thousand facets in each). Insects see green-yellow, blue and ultra-violet rays. Many of them hear well, including ultrasound.

· The respiratory system of insects is represented by tracheae. Tracheal trunks, branching many times in the body of an insect, openholes-spiracles on the sides of the metathoracic and abdominal segments.

· The excretory organ, in addition to special tubes-outgrowths of the intestine, is alsofat body,where metabolic products are deposited.

development of insects. All insects are dioecious animals. After internal fertilization, the female lays several dozen eggs. The female always lays her eggs near the food that the larva will eat: plant leaves, soil, water surface, sewage, meat, etc. After a while, a larva hatches from the egg, which actively feeds and grows. Depending on the type of larva and its development into an adult insect, it may have a complete or incomplete transformation.

With a complete transformation - Metamorphosis develops in four stages: egg, larva, pupa, adult insect (imago). The larva is completely different from the adult form, but more like an annelids. Its type of food and habitat may not coincide at all with that of an adult insect. The larvae have chewing mouthparts, actively feed and grow, molting several times. When the larva reaches its maximum size, it freezes, becomes covered with a new chitinous shell or cocoon and turns intochrysalis.At this stage, insects do not feed (sometimes the whole winter). After some time, an adult form, an imago, appears from the pupa, with all the signs characteristic of an adult insect (wings, limbs, mouth apparatus).

Development with complete metamorphosis is characteristic of evolutionarily younger orders. Evolutionarily older insects are characterized by incomplete transformation.

With incomplete conversion development proceeds in three stages: egg, larva-adult. The pupal stage is absent. The larva in body shape resembles an adult insect, differing only in size and lack of wings. In the process of growth, the larva molts several times before reaching the size of an adult. In insects with incomplete metamorphosis, eggs usually hibernate.

The class of insects is very diverse. It has more than 30 detachments, differing from each other mainly in the structure of the wings, mouthparts and development.

The most widespread lower insects with incomplete metamorphosis arecockroaches, dragonflies, orthoptera (grasshoppers, locusts, crickets), hemiptera (bugs).

The higher insects with complete metamorphosis areColeoptera (beetles), Lepidoptera (butterflies), Hymenoptera (bumblebees, wasps, bees, ants, riders), Diptera (flies, horseflies, mosquitoes). mimicry characteristic for unprotected individuals— imitation of protected individuals (wasp flies).

Insects may have chemical "weapons" of defense, like bombardier beetles, which can shoot out with the end of the abdomen to form a smoky cloud. Ants excrete a large number of formic acid, which has a burning effect.

There are social insects: bees, ants, termites, forming large families - colonies in which duties are clearly distributed, and individuals are differentiated: queen (large female), drones (males), workers, or soldiers.

Due to the ability to actively move, insects inhabited all environments of life. They can be found in all natural areas.

Most insects have small size(up to 1-3 cm). This allows them to live in places inaccessible to other animals. Thanks to various adaptations, they successfully survive in the struggle for existence.

Insects are characterized by seasonal and daily activity, migration in space. So, for example, butterflies can be diurnal and nocturnal. Locusts are capable of moving great distances.

The behavior of insects is made up of direct reactions to environmental factors, and is also determined by instincts - hereditary unconditional reflex activity. Instincts are very complex and provide the expediency of the insect's behavior. For example, a bee, performing a certain "dance" (flight), shows the way to flowers with nectar. By the evening, ants close the passages to the anthill, expel foreign individuals. Some ants grow fungal mycelium in anthills, cultivate aphids, “milk” them, forcing them to release special sugary substances.

Others are of great benefit, destroying pests of plants, contributing to their pollination. So, for example, riders lay eggs in larvae or adults of other insects, thereby exterminating many agricultural pests.

There are insects bred by man: the silkworm, from the cocoon of which silk fiber is obtained.Serve people and bees. Soil insects loosen the soil, contribute to its aeration, the accumulation of organic matter. In general, insects are an important link in complex food chains and are an integral part of various biocenoses.

1) Segmented body, jointed limbs.
2) Chitin cover.
3) The circulatory system is open, the heart tube is on the dorsal side.
4) Periopharyngeal nerve ring and ventral nerve cord.

Differences

1) Body sections: in crayfish and spiders - the cephalothorax and abdomen, in insects - the head, chest and abdomen.

2) Legs: crayfish can have a different number (crayfish 10), spiders 8 (4 pairs), insects 6 (3 pairs).

3) Wings only in insects, 2 pairs, located on the chest.

4) Eyes: in crayfish, complex, faceted (consisting of many simple eyes), in spiders, simple, in insects, simple and complex.

5) Mustache: crayfish have 2 pairs, spiders do not, insects have 1 pair.

6) Respiratory and circulatory systems:

• Crayfish breathe through gills, oxygen from the gills to all organs of the body is carried by blood, so the circulatory system is well developed.
• Insects breathe through tracheae: thin tubes that carry air to every cell in the body. Blood does not carry oxygen, so the circulatory system is poorly developed (blood carries nutrients, metabolic products, hormones, etc.)
• Spiders breathe with lungs and tracheae, the circulatory system is moderately developed.

7)excretory system: metanephridia (green glands) and malpighian vessels, in crayfish only metanephridia.

In all insects, development is indirect (with metamorphosis, with transformation). The transformation can be complete or incomplete.

• Complete: egg, larva, pupa, adult insect. It is typical for butterflies (lepidoptera), beetles (coleoptera), mosquitoes and flies (dipterous), bees (hymenoptera), etc.
• Incomplete: egg, larva, adult (no pupal stage). It is typical for grasshoppers and locusts (Orthoptera), bedbugs.

Choose one, the most correct option. The grasshopper has development
1) indirect
2) with a doll
3) direct
4) with complete transformation

Answer

Choose one, the most correct option. What are the functions of the circulatory system of insects?
1) transports nutrients and harmful waste products
2) carries out the transfer of gases
3) delivers oxygen to cells
4) participates in metabolism and energy conversion in the cell

Answer

Establish the sequence of stages of development of the cabbage white
1) egg
2) chrysalis
3) caterpillar
4) adult insect

Answer

1. Establish a correspondence between the sign of the animal and the class for which it is characteristic: 1) arachnids, 2) insects
A) pre-digestion of food outside the body
B) dividing the body into cephalothorax and abdomen
C) eyes are simple, from two to eight pairs
D) the presence of one pair of antennae on the head
D) the presence of three pairs of limbs on the chest
E) compound eyes, complex structure

Answer

2. Establish a correspondence between the sign of the animal and the class for which it is characteristic: 1) arachnids, 2) insects
A) the presence of the cephalothorax and abdomen
B) one pair of antennae
B) four pairs of walking legs
D) eyes are simple or absent
D) only tracheal breathing

Answer

3. Establish a correspondence between the signs of animals for which they are characteristic: 1) spider, 2) insect
A) respiratory organs - only the trachea
B) developed chelicerae
B) excretory organ - fat body
D) three pairs of walking legs
D) the body is divided into three sections
E) four pairs of walking legs

Answer

4. Establish a correspondence between the structural features of arthropods and the class for which they are characteristic: 1) arachnids, 2) insects. Write the numbers 1 and 2 in the order corresponding to the letters.
A) the body consists of the head, chest, abdomen
B) have a mustache
B) 3 pairs of walking legs
D) there are only simple eyes
D) most have wings
E) there are lung sacs and tracheae

Answer

5. Establish a correspondence between the characteristics and classes of arthropods: 1) Arachnids, 2) Insects. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) respiratory organs - exclusively trachea
B) direct development in the majority
C) the presence of three pairs of limbs
D) blood does not carry gases
D) the body consists of the cephalothorax and abdomen
E) the presence of one pair of antennae

Answer

Choose one, the most correct option. Incomplete transformation is characteristic
1) butterfly Peacock eye
2) fire bug
3) dragonfly-yoke
4) housefly

Answer

1. Establish a correspondence between the insect and the type of its postembryonic development: 1) with incomplete transformation, 2) with complete transformation
A) Asiatic locust
B) May beetle
B) cabbage white
D) housefly
D) green grasshopper
E) honey bee

Answer

2. Establish a correspondence between the type of animal and the type of its postembryonic development: 1) with complete transformation, 2) with incomplete transformation. Write the numbers 1 and 2 in the correct order.
A) desert locust
B) bread beetle
B) common praying mantis
D) honey bee
D) birch moth

Answer

3. Establish a correspondence between a representative of the class of insects and the type of its development: 1) with incomplete transformation, 2) with complete transformation. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) locust
B) stag beetle
B) a cockroach
D) grasshopper
D) bed bug
E) cabbage butterfly

Answer

4. Establish a correspondence between insect species and types of their development: 1) with complete transformation, 2) with incomplete transformation. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) beetle
B) forest bug
B) green grasshopper
D) May beetle
D) urticaria butterfly

Answer

5. Establish a correspondence between insect species and types of their development: 1) with complete transformation, 2) with incomplete transformation. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) swimming beetle
B) migratory locust

B) bear
D) ladybug
D) dragonfly rocker
E) red ant

Answer

COLLECTING 6

D) gravedigger beetle

D) Colorado potato beetle
E) a bug is a harmful turtle

Establish a correspondence between the trait and the type class Arthropods: 1) Crustaceans, 2) Insects. Write the numbers 1 and 2 in the correct order.
A) cephalothorax and abdomen
B) Excretory system - antennal glands
C) respiratory organs - trachea
D) Respiratory organs - gills
D) Three pairs of walking limbs
E) head, thorax and abdomen

Answer

Establish a correspondence between the characteristics and classes of arthropods to which it belongs: 1) crustaceans, 2) arachnids. Write the numbers 1 and 2 in the correct order.
A) the presence of two pairs of antennae
B) regulation of the number of insects
C) the presence of four pairs of limbs
D) the transfer of certain types of diseases dangerous to humans
D) external digestion
E) purification of water bodies from organic residues

Answer

Read the text. It is known that the king crab is one of the largest species of crustaceans, an inhabitant of the Far Eastern seas. Using this information, select three statements from the text below that relate to the description of these features of this organism. Write down the numbers under which they are indicated. (1) The crab breathes oxygen dissolved in water. (2) The muscles of the limbs of the crab are used as food. (3) Crabs are eaten by humans. (4) The body parts of a crab are the cephalothorax and abdomen. (5) Poaching significantly reduces the crab population. (6) Males reach 23 cm in shell width, 1.5 m in leg span, and 7 kg in weight.

Answer

Choose three correct answers from six and write down the numbers under which they are indicated. What are the characteristics of the animal shown in the picture?
1) closed circulatory system
2) division of the body into head, thorax and abdomen
3) abdominal nerve chain
4) four pairs of legs
5) one pair of antennae
6) breathing with the help of lung sacs and trachea

Answer

All but two of the characteristics below are used to describe the animal depicted in the drawing. Identify two terms that "fall out" from the general list, and write down the numbers under which they are indicated.
1) five pairs of walking legs
2) the presence of two to twelve simple eyes
3) the presence of a green gland
4) the body consists of the cephalothorax and abdomen
5) the presence of the spider gland

Answer

Choose three correct answers from six and write down the numbers under which they are indicated. Specify the features characteristic of insects with incomplete metamorphosis:
1) three stages of development
2) external fertilization
3) the larva looks like an annelids
4) the larva is similar in external structure to the adult insect
5) the larval stage is followed by the pupal stage
6) the larva turns into an adult insect

Answer

Establish a correspondence between the classes of animals and their characteristics: 1) crustaceans, 2) insects. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) respiratory organs - trachea
B) respiratory organs - gills
B) three pairs of walking legs
D) five pairs of walking legs
D) direct development
E) development with complete and incomplete transformation

Answer

All but two of the examples below refer to orders of insects with complete metamorphosis. Identify two examples that "fall out" from the general list, and write down the numbers under which they are indicated.
1) Coleoptera
2) Hemiptera
3) Diptera
4) Orthoptera
5) Lepidoptera

Answer

Choose three correct answers from six and write down the numbers under which they are indicated. What are the characteristics of insects?
1) division of the body into the cephalothorax and abdomen
2) division of the body into head, thorax and abdomen
3) tracheal respiratory system
4) pulmonary respiratory system
5) four pairs of walking limbs
6) six walking limbs

Answer

Select three statements related to the difference between arachnids and insects.
1) They have an external chitinous skeleton, which serves as a frame for the entire body.
2) Four pairs of simple eyes.
3) Open circulatory system.
4) There are Malpighian vessels.
5) Four pairs of walking legs.
6) The body consists of the abdomen and cephalothorax.

Answer

Choose one, the most correct option. Aromorphic changes in arthropods include the appearance
1) organs of sight and touch
2) closed circulatory system
3) limbs, consisting of departments
4) nervous system in the form of a chain

Answer

Establish a correspondence between the sign of animals and classes: 1) Insects, 2) Crustaceans. Write the numbers 1 and 2 in the correct order.
A) respiratory organs - trachea
B) three pairs of limbs
C) five pairs of walking legs
D) respiratory organs - gills
D) hard chitinous shell
E) excretory system - Malpighian vessels

Answer

Choose three options. What features unite crayfish, cross-spider and May beetle into the Arthropod type?
1) the same structure of the excretory organs
2) chitinous cover of the body
3) compound eyes
4) closed circulatory system
5) division of the body into sections
6) abdominal nerve chain

Answer

Set the correspondence between the animal and the class to which it belongs: 1) Arachnids, 2) Insects
A) honey bee
B) scorpion
C) red forest ant
D) malarial mosquito
D) taiga tick

Answer

Establish a correspondence between an arthropod and the class to which it belongs: 1) Crustaceans, 2) Arachnids, 3) Insects. Write the numbers 1, 2 and 3 in the correct order.
A) scorpion
B) spider-cross
B) egg-eating rider
D) king crab
D) Black Sea shrimp
E) bed bug

Answer

Establish a correspondence between examples and classes of animals: 1) Arachnids, 2) Insects, 3) Crustaceans. Write down the numbers 1-3 in the order corresponding to the letters.
A) king crab
B) bed bug
B) ladybug
D) spider-cross
D) Black Sea shrimp
E) common praying mantis

Answer

Find three errors in the given text. Specify the numbers of proposals in which they are made.(1) Insects are dioecious animals. (2) The females lay fertilized eggs, which hatch into larvae. (3) In some insects, the larvae do not look like adults, this type of development is called development with incomplete transformation. (4) In development with incomplete transformation, the insect goes through the phases: egg - larva - pupa - adult. (5) Different nutrition of larvae and adults reduces competition and promotes the survival of the species as a whole. (6) Grasshoppers, crickets, bedbugs, and mosquitoes are representatives of insect orders with incomplete metamorphosis. (7) Representatives of insect orders with complete transformation include butterflies, beetles, bees, bumblebees.

Answer

Answer

Choose three correct answers from six and write down the numbers under which they are indicated. What features of organization contributed to the wide distribution of insects on the planet?
1) development of a secondary body cavity
2) the presence of the nervous system of the nodal structure
3) high fertility
4) a variety of oral apparatus
5) the presence of stinging organs
6) the presence of wings

Answer

Choose three correct answers from six and write down the numbers under which they are indicated. If in an animal the heart has the structure shown in the figure, then this animal is characterized by
1) the presence of hemoglobin in erythrocytes
2) pelvic kidneys
3) tubular nervous system
4) open circulatory system
5) branched tracheal tubes
6) indirect development

Answer

Establish a correspondence between characteristics and organisms. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) gill breathing
B) has two pairs of antennas
B) simple eyes
D) has five pairs of walking legs
D) usually has spider glands
E) walking legs do not have claws at the end

Answer

© D.V. Pozdnyakov, 2009-2019

Task 1. Perform laboratory work.

Topic: "The external structure of the insect".

Objective: to study the external structure of insects on the example of a cockroach or a large beetle.

1. Make sure that the workplace has everything you need to perform laboratory work.

2. Using the instructions given in paragraph 26 of the textbook, complete the laboratory work.

3. Fill in the table.

Task 2. Fill in the table.

Task 3. Color the internal organs of the insect (red - blood organs; yellow - organs of the nervous system; green - organs of the digestive system) and label them.

Fill in 4. Fill in the table.

Digestive system, digestion, type of nutrition mouth, pharynx, esophagus, stomach, intestine. Extracellular digestionmouth, oral cavity, pharynx, esophagus, goiter, chewing stomach, midgut, hindgut, anusSense organsSense organs

Comparative characteristics of arachnids and insects
Comparable feature	Class
	arachnids	Insects
Distribution and lifestyle	land and terrestrial arthropods	all habitats except seas and oceans
Body sections	cephalothorax and abdomen, no antennae, 2 pairs of mouthparts	head, chest, abdomen; 1 pair of compound eyes, 1 pair of antennae
Limbs: number, location, structure	4 pairs of walking legs	three pairs of legs or wings
Digestive system, digestion, type of food	mouth, pharynx, esophagus, stomach, intestine. extracellular digestion	mouth, oral cavity, pharynx, esophagus, goiter, chewing stomach, midgut, hindgut, anus
Respiratory system	lungs and trachea	trachea
Nervous system	cephalothoracic ganglion	large supraesophageal node
sense organs	well developed, several pairs of eyes	well developed
Reproduction and development	fertilization internal	dioecious insects

Task 5. Write down the numbers of the correct statements.

1. The class Insects includes all tracheal-breathing arthropods with three pairs of legs.

2. In all insects, the body consists of a head, chest and abdomen.

3. The legs of insects are located on the chest and abdomen.

4. Insects live not only on land, but also in water and soil.

5. Insects eat anything that contains organic matter. Some of them even adapted to eat wool, wood and beeswax.

6. Along with compound eyes, many well-flying non-insects also have simple eyes.

7. Antennae of insects - organs of smell.

8. Aquatic insects have developed gill breathing.

9. Insect excretory organs - Malpighian vessels.

10. Blood in insects flows only through the blood vessels.

Correct statements: 1, 2, 4, 5, 6, 7, 9.

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This part of the body has many variants of morphology, so it is quite difficult to talk about some kind of absolute uniformity in its external structure.

Number of abdominal segments

In typical cases, it includes ten or eleven segments - "rings" that are attached to each other and form the visceral section. The 11th segment is found only in bessyazhkovyh, two-tailed and other Primary wingless - the most primitive forms of insects. In highly developed species, the posterior segments are reduced or screwed into the body.

The number of abdominal segments also depends on the stage of development: they, as a rule, have the maximum possible number, and they have fewer.

In adults, they also often merge with each other and have uneven thickness, therefore, owners of a short abdomen and small body sizes are distinguished by the fact that on their visceral region the number of clearly distinguishable rings can be reduced to three. However, in most representatives of the insect class, the average number of segments ranges from 5 to 8.

The first segment of the abdomen in the stalked-bellied (Hymenoptera) is called and merges with the back of the thoracic region, and the second (in ants - both the second and the third) is transformed into a thin stalk. Due to this structure, the abdomen acquires greater mobility in relation to, and it becomes more convenient for the insect to manipulate (bees) or inject injections (riders).

Segment structure

The cuticular rings of the visceral region have a structure resembling morphology. Each segment is divided into two parts in the form of semirings - upper and lower. On the sides of the body, they are interconnected by a thin elastic pleyral membrane. (a photo) The same movable structure is located at the joints of adjacent segments. This adaptation allows the abdomen to change quite strongly in size, stretching 2-5 times after eating or during maturation (in females).

In song insects - mayflies, cicadas - there are air cavities in the abdomen. By stretching and contracting the playral membranes, they inflate and release air from the abdominal region, being able to reproduce characteristic sounds. And some, for example, worker ants of the genus Myrmecocystus, have special reserve organs within the abdomen, in which they accumulate food substrates in large quantities for feeding the inhabitants of the nest and for their own nutrition. Being "filled", the abdomens of these ants look like transparent golden drops several times larger and ; as needed, insects regurgitate food for their fellow tribesmen, and then replenish stocks again.

Atypical shape of the abdomen

Abdominal shape

The shape of the abdomen can be very different, and its features mainly depend on the lifestyle: the better the insect flies, the more streamlined and regular the shape of its visceral region. In order not to resist when moving in the air, all appendages on the abdomen (primarily hairs) grow in the direction from front to back.

In addition to being cylindrical, the abdomen can be spherical, flattened in the upper-lower direction, clavate, triangular in cross section, etc. In most beetles, it is thickened in the middle and narrowed towards the end, while its lower surface is almost flat, and the upper, under, is convex.

In front, the abdominal region can directly pass into (butterflies), or be separated from it by a “stalk” (bumblebees) or constriction, as in some ground beetles. In the back, it most often narrows spindle-shaped, forming a rounded top. However, for example, bark beetles are distinguished by a shortened, as if “chopped off” abdomen, which has the shape of a truncated cone. (a photo)

Abdominal appendages in the form of altered limbs

and external formations of the abdomen

By origin and purpose, all additional structures of the visceral department can be divided into three groups:

Due to the fact that different insects have a different number of segments of the abdomen, many appendages and organs do not have a "permanent" place and can be located in different parts of it. Most of them are located at the posterior end of the body.

() - holes closed by a thin membrane through which gas exchange occurs. They are located on each segment of the visceral region, on the sides, in the area of ​​​​the connection of the upper and lower half rings.

False legs

- reduced and modified limbs. They do not contain locomotor muscles and do not serve for movement in adults, but have a simplified structure and are actively used in true and false caterpillars. In addition, on the body of insects of any stage of development, there may be reduced legs that do not perform functions or are generally presented in the form of outgrowths. For example, the caterpillar of the royal hazelnut butterfly has a very unusual view: in addition to the main false ones, on each segment of its abdominal region there are several reduced branched pseudopods. (a photo)

- jointed appendages located on the last segment of the abdomen in the form of a "tail". There are two of them, less often three, they come from a reduced 11th segment and can have different lengths: from almost imperceptible in a fly to very pronounced in a house cricket. The higher forms of insects lack these additions.

Sexual appendages and organs

- components of the reproductive system, which are usually located on 8 or 9 segments. Conventionally, they are considered to be the main part of the abdomen. Moreover, sometimes the segment of the visceral region on which they are located is isolated into a separate genital segment. Accordingly, the rings lying in front of it are called pregenital, and behind - postgenital.

Depending on the features of morphology, in many insects the abdomen can acquire additional significance. In caterpillars moving on false legs, it is involved in the implementation of the locomotor function. Special muscle bundles responsible for increasing and decreasing the length of the body connect adjacent segments to each other. Thus, relaxing and straining them "to the beat" of walking, accelerates its progress.

The movable connection of the abdomen with the chest and the presence of an altered one in the stalked-bellied facilitate their defense. The glowing organs of fireflies and the resonating cavities of cicadas help them communicate and ensure safety, and with the help of the accumulation of nutrients, ants - "honey barrels" are able to survive even in adverse conditions of deserts and semi-deserts.