A colony of arthropods burrowing in the substrate is a typical picture of modern tropical forests. Insects, cockroaches, are the oldest representatives of neoptera with incomplete metamorphosis. Over the years of evolution, they have not undergone major changes. Arthropods have become true cosmopolitans, spreading across all continents except Antarctica. Cockroaches are hardy and agile, shy and omnivorous. Some species have become synanthropic insects.
Classification
The order Cockroaches (Blattopera) belongs to the class insects, phylum arthropods. Termites are included in a large group of 7,570 species. Cockroaches are members of the superorder Cockroaches (Dictyoptera). It includes new-winged insects with incomplete metamorphosis. 4640 species of cockroaches have been found and studied in the world. There is a constant debate among scientists regarding taxonomy. The authors divide cockroaches into different numbers of families and subfamilies, classify them together and separately with termites.
According to the latest data, 8 families have been identified: Nocticolidae, Corydiidae, Blaberidae, Ectobiidae, Cryptocercidae, Tryonicidae, lamproblattidae, Blattidae. The greatest diversity of species is found in the tropics. Insects found an abundance of food and shelter in warm and humid forests. There are 55 species of cockroaches living in the CIS. Some of them are synanthropic, living next to humans.
Information. Is a cockroach an insect or an animal? In everyday reference, animals are four-legged vertebrates, but in scientific classification they include many organisms. Insects are arthropod invertebrate animals.
Adviсe
- If you are faced with a cockroach infestation, you should carry out a very thorough and full-scale pest control. If you do not treat at least one area, cockroaches will survive on it and infest your home again.
- Furniture cockroaches often hide in warm places, such as the top shelves of cabinets.
- If you have a cockroach infestation, it is highly recommended that you store food in airtight packaging or containers to avoid contamination or infestation. The same goes for garbage.
- Black cockroaches like to hide in or near drains, pipes, and dark, cool places.
- Prussians mainly live in places where food is prepared, that is, kitchens.
Structure of a cockroach
Despite the species diversity of the order, the body structure of its representatives is largely similar. The morphology of the imago (adult individuals) is typical. Differences appear in size and color.
External structure of a cockroach
The body of insects is flattened and oval in shape. This structure allows you to crawl into narrow cracks and holes. The length of the imago ranges from 9 to 95 mm. The color of the cover is often dark - brown, black, brown. Reddish and coffee colors are less common. Nocturnal lifestyle, secrecy and the need for camouflage do not require the presence of bright colors.
Interesting fact. The largest species is the Madagascar hissing cockroach, its length is up to 100 mm. For comparison, the size of Prussians is 9-10 mm. More popular information will be told in “Interesting facts about cockroaches: what we know about these insects.”
Body parts of a cockroach
Insects consist of three main sections: head, thorax, and abdomen. Dividing the body promotes mobility. Functional significance of each department:
The head is triangular or heart-shaped, movable, covered from above by a pronotal shield. The organs of vision and touch are located on it. Antennae are movable appendages consisting of segments. The type is bristle-like. The functions of the antennae of a cockroach are touch and smell. With the help of appendages, they determine the taste of food, find sexual partners, and communicate between individuals. The mouthparts are directed downwards.
Information. The number of segments in the antennae increases with changing ages of the larvae. They are added after molting.
Thorax - the middle section consists of three segments, divided into tergites and sternites. The upper half rings form the back, the lower half rings form the chest. The largest segment is the pronotum; it can be flat or convex. Elytra and wings are attached to it. Each part of the chest belongs to one pair of limbs.
The abdomen is the largest section and consists of 10 segments. At its end there are paired segmented appendages of the cerci. The abdomen houses the respiratory and digestive systems, and in females the ovipositor. The anal plate is located on the 10th tergite.
Systems from the inside
Experts say that insects are driven by the instincts of thirst, hunger, safety, and sex. It becomes interesting whether the cockroach has a brain. Another interesting observation suggests that a Prussian can live for a week without a head.
Nervous system
The functions of the brain are performed by 2 large nerve plexuses located in the head. They are responsible for the functional activity of the eyes, lips, and antennae. The central nervous system consists of 11 nodes, which are responsible for the movement of the wings, paws, head, thoracic region, and sensitivity of the reproductive system.
Interesting!
The division of functions between the brain center and the central nervous system makes it possible to live without a head for almost a month in cool conditions. The brain does not regulate breathing and is not responsible for digestion. There is no pressure in the circulatory system, so the cockroach does not bleed. Energy is not wasted, which allows you to do without food.
The nervous system of the cockroach ensures the activity of all senses and coordinates movement.
Circulatory system
A cockroach's blood is white, functions freely inside, and washes its organs. There is no pressure in the system, so the Prussian does not suffer from bleeding in the event of a serious injury.
The cockroach's heart is formed by a tubular organ that helps circulate blood inside. But the process occurs slowly, which is why cockroaches are unusually sensitive to low and high temperatures. At zero, all life processes slow down; at temperatures above 35 degrees Celsius, the insect dies from dehydration.
Respiratory system
On the sides of the abdomen there are 10 segments of spiracles, which provide oxygen to all internal organs and systems. An interesting feature of holding their breath for 40 minutes makes cockroaches the laziest creatures on the planet. Insects do not breathe for most of their lives.
Features of the structure of cockroaches
Each of the main parts of the body contains organs that provide vital functions for insects.
What kind of eyes does a cockroach have?
The main organ of vision in cockroaches is compound or compound eyes. They are located on the sides of the head. They have different sizes (large in winged forms) and are kidney-shaped. The interocular space is well defined. Additional organs of vision, simple eyes, help assess the intensity of light. They are small and located at the top of the head. How many eyes does a cockroach have? Insects have 2 main eyes and 2 simple ocelli, which have atrophied in some species.
You will learn about the phenomenal endurance of insects in the article “Without food, water and a head: how long do cockroaches live?”
Type of cockroach mouthparts
Insects that eat solid food have developed gnawing type mouthparts. It consists of several parts:
- Upper lip - sensitive hairs on its surface help in studying food.
- The upper jaw (mandibles) consists of a durable chitinous plate with teeth. Used for biting and grinding food.
- The lower jaw (maxilla) is a movable organ consisting of several segments that supports food during grinding.
- The lower lip helps push food into the pharynx; its palp is an organ of touch.
The cockroach's mouthparts have remained unchanged throughout the entire period of its existence. It allows you to absorb plant residues and any organic matter.
Cockroach limbs
Running is the main method of movement for representatives of the cockroach order. The structure of their legs helps them with this. The limbs consist of 5 parts. They are attached to the body with the help of a coxa, which has developed muscles. The longest segments are the thigh and tibia. The flexible foot consists of 5 segments. There are spines on the legs and thighs. How many legs does a cockroach have? Insects have 2 pairs of limbs, each of which is attached to a specific part of the chest.
Information. Some species have a suction cup on the foot, allowing insects to move along vertical surfaces.
Limbs are used for more than just running and jumping. With them, the imago cleans the antennae and body of food debris. The legs are flexible and mobile, they allow you to quickly change the trajectory of movement in case of danger. The average speed of a Prussian is 3-4 km/h.
The structure of the wings of a cockroach
The ancestors of insects had developed wings and the ability to fly. Many modern species have lost it. Appendages appear only in adults. They consist of two pairs. The first is the leathery elytra. They perform a protective function and do not participate in flight. The second pair are membranous wings. The length and development of the appendages depends on the species. In females, the wings are less developed. In a calm state, insects fold them on their backs.
Flying cockroaches are most often found in the tropics, but some species are found in Central Asia and Europe. Among domestic insects, the American cockroach demonstrates the ability to fly. Although Prussians have long wings, they rarely spread them and can glide.
Internal structure of a cockroach
The vital activity of insects is provided by the main systems:
- circulatory;
- nervous;
- digestive;
- excretory
To understand how insects can live for months without food and about a week without a head, we need to study them in more detail.
Circulatory system - blood (hemolymph) flows in the space between the internal organs of the insect. There is only one vessel in the body connected to the heart. Main muscle. The pumping blood consists of 13 chambers, 2 of them are in the chest, the rest in the abdomen. The function of blood is to transport nutrients and remove waste products. The respiratory system distributes oxygen. This is the main reason for the reduction of blood vessels. The blood movement is slow, the insect does not maintain a constant body temperature.
Information. If you deprive a cockroach of its head, the hemolymph quickly sinteres and the body does not bleed.
When depicted schematically, the respiratory system resembles a tree. It consists of a tracheal system that encircles all important organs. Branches extend from the main trachea, gradually decreasing in diameter. The system is connected to the external environment using 10 stigmas, which are called spiracles in cockroaches. Two pairs of stigmas are located on the sides of the chest, the main part is located on the abdomen. Breathing occurs when the department contracts.
The digestive system is an intestine divided into several sections. In the mouth, food is ground and moistened with saliva. Next, it is pushed into the pharynx, then into the crop, where digestion and absorption begin. Food is fed into the stomach in small portions. It is prepared and sent to the midgut. In this section, the digestive secretion is secreted and the main absorption occurs. Excrement comes out through the anus.
The excretory system or Malpighian vessels remove waste products from the body through the hindgut.
What is the body of a cockroach covered with?
The typical cover of arthropods is a chitinous shell. For cockroaches, this is a shell that protects internal organs. It allows the body to maintain its shape and serves as a skeleton. The outer cover prevents the rapid evaporation of moisture. At the base of the limbs, the layer of chitin is thinner to provide mobility to the legs. The hard shell limits the growth of insects. During development, the larvae have to shed it. The tight shell cracks and the insect crawls out of it. At first his body is white and soft. This is a sign of the absence of chitin. After a few hours the cover is restored.
Information. An encounter with molted arthropods gave rise to myths about white cockroaches.
Troop Lice
Represented exclusively by external parasites of mammals. The sucking mouthparts of lice are structured in a unique way, unlike, for example, the sucking mouthparts of bedbugs (Fig. 17).
Rice. 17. Squad Lice
The transformation of lice is incomplete. They don't have wings.
Lice should never be confused with fleas, which is often done due to their similar parasitic lifestyle. In fleas, the transformation is complete - these are completely different insects (Fig. 18).
Rice. 18. Louse and flea
Like other bloodsuckers, lice must somehow prevent blood from clotting in their digestive system.
To do this, substances that prevent blood clotting - anticoagulants - are released into the wound along with saliva.
The limbs of lice are tenacious, strong, and claw-shaped. With their help, they are attached to hair or clothing fibers.
About 250 species of these insects are known. Their body length ranges from 0.4 to 6 mm. Female lice lay eggs on hair or clothing. These eggs are called nits (Fig. 19). In total, a female can lay up to 300 eggs during her life.
Lice are carriers of pathogens of various diseases. The most dangerous among them are chain fever and relapsing fever. The habitat of lice is hair-covered areas of the body and human clothing. Prevention of lice means keeping your body and clothes clean. The main measure to eliminate lice is the use of special products that are sold in pharmacies.
Features of reproduction
Cockroaches have male and female species. They attract potential partners with the help of chemical odors - pheromones. Males of some species perform courtship dances during courtship. The fertilized female lays eggs in a special capsule formed in the abdomen. In a special chamber, sticky secretions envelop each egg and form a shell. Females carry it in their abdomen and periodically push it out for ventilation. For embryo development, a high temperature of about 30° is required. A detailed description of ootheca in the article “How many cockroaches hatch from one egg?”
The duration of carrying depends on the species, some shed the ootheca after 7-14 days, others keep it in the abdomen until the larvae are born. The egg cocoon helps increase the survival rate of the offspring. This is the first food of the larvae. The young are born white, with a soft coat. The larvae stay near their mother or burrow into the ground. They go through 3-12 instars before turning into adults. Each is accompanied by molting - shedding a tight shell.
The offspring are called larvae or nymphs. Outwardly, they resemble adults. The differences are:
- small size;
- absence of genitals;
- a small number of antennal segments;
- lacking wings.
Larvae make up the bulk of the colony. They show more caution than adults and burrow into the ground more often. Development takes from several months to 1-2 years. When the temperature drops, the larvae grow poorly.
General information
Black cockroaches belong to the order Blattodea, which has approximately 4,600 species. These are one of the oldest arthropods that appeared on Earth approximately 300 million years ago. This is evidenced by fossils of dead ancestors preserved in amber millions of years ago.
Cockroaches have inherited the trait of photophobia from their distant ancestors. Insects prefer a nocturnal lifestyle. Large black cockroaches, of which there are about 1 thousand individuals, eat 9.5 kg of food in one year, but they simply dirty much more food. As soon as darkness falls, insects go in search of food: for crumbs of bread, pieces of vegetables, particles of granulated sugar. Cockroaches also love to feast on leather creams, laundry soap, shoe polish and ink.
Nutrition
In natural conditions, most cockroaches are vegetarians; they eat fallen leaves, fruits, and dead plants. Some species are omnivores, their diet expanded to include the remains and excrement of animals. Domestic insects feed on any food found in the apartment. Preference is given to sweets, bread and pastries, as well as fruits. You will learn about the diet of domestic pests in the material “What do cockroaches eat: what diet should you prepare at home?”
Subkingdom multicellular (METAZOA)
Phylum ARTHROPODA
Subtype Gill-Breathing (BRANCHIATA)
Class Crustaceans (CRUSTACEA)
Subtype CHELICERATA
Class Arachnida (ARACHNIDA)
Task 1. Consider the structure of the opened crayfish. Indicate in the drawings the main elements of the external and internal structure.
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1.1. Limbs of crayfish.
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1.2. Opened crayfish.
Task 2. Examine microscopic specimens and drawings of cladocerans, copepods and barnacles.
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2.1. Daphnia. The body is enclosed in a shell. The head section is free. Antennas are branched. There is an eye formed by the fusion of two. The thoracic limbs do not perform the function of movement. They are covered with bristles. The abdomen is tucked under the chest. Does not carry limbs. The heart is located on the dorsal side. There are no vessels. Females are larger than males. Females have a brood chamber. In the development cycle, the appearance of a parthenogenetic generation of females is observed. The appearance of males occurs at the end of summer, beginning of autumn, when bisexual reproduction is observed.
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2.2. Cyclops. The body is segmented and consists of a cephalothorax and abdomen, ending with a furca. The fork contains feathery bristles. There is no sink. Unpaired eye. The cephalothorax is ovoid and consists of five segments. All head segments merged together with the first chest segment. The male's abdomen also consists of five segments, while the female's has only four, since the first segment of her abdomen is fused with the second and is called the genital segment.
Task 3. Study the external structure of arachnids using a drawing and a textbook. Consider the location of the main organs. Make signatures.
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3.1. External structure of a scorpion.
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3.2. External structure of the spider.
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3.3. Ixodes (dog) tick (Ixodes ricinus) hungry female from the ventral side.
Task 4. Draw the development cycle of a pasture tick.
The harmfulness of insects
Synanthropic species living in human homes are a potential health threat. In search of food, they examine sewers, garbage chutes, and rodent holes. Pathogenic bacteria, fungi, and helminth eggs remain on the legs of insects. Dangerous microorganisms are transferred to food, bedding, and furniture. If you do not wash your hands regularly, there is a high risk of contracting dysentery, tuberculosis, diphtheria, and hepatitis.
Chitin particles scattered by the larvae after molting cause severe allergic reactions. People develop chronic rhinitis and asthma. All information about the threat to human health is in the article “What are the dangers of cockroaches: can a small insect cause big problems?”
In addition, pests spoil food, books, and wallpaper. They prefer secluded warm places, so they crawl into electrical appliances. Insects cause short circuits and equipment breakdowns. In the fight against synanthropes, any means are used: freezing premises, glue traps, poisoned baits, insecticides. Treating apartments with special chemicals is an effective way to get rid of insects.
Only a few synanthropic species of cockroaches have received the status of pests of stocks and carriers of infectious diseases. The main part of insects plays a significant role in the world ecosystem. Arthropods are destroyers of plant and animal debris and food for animals, birds and reptiles.
Lifestyle and habitat
Black cockroaches prefer cool, damp and dark rooms (basements, cellars, sewers near garbage disposals), since they are predominantly nocturnal and cannot exist without water.
It will not be possible to meet them during daylight hours. The exception is a large accumulation of young insects and the lack of the required amount of food, which forces them to look for it during the day near sewers and containers with garbage and food waste.
The flat structure of the body allows them to hide in the cracks of houses and impassable areas. It has been noticed that in apartment buildings this type of insect lives mainly on the ground floor and first 2-3 floors. Black cockroaches in an apartment are usually concentrated in secluded places in bathrooms and bathrooms, under kitchen units in the area of the sink or trash can.
Due to the peculiarities of their metabolism, longhorned beetles cannot live in the wild with a cold climate; for them, temperatures below 0 degrees are considered critical. At sub-zero temperatures, cockroaches quickly die.
In the private sector (house), black cockroaches hide in old foliage, sheds, cellars, and when it gets dark, they get out of their shelters and go in search of food, entering the house along previously studied paths.
An interesting feature is that black and red brothers cannot coexist in the same territory. In places where Prussians settled, oriental cockroaches will never appear and vice versa.
Insects often visit polluted places and carry a lot of pathogenic bacteria on their tenacious legs, which is why they emit an unpleasant odor and can be dangerous to human health.
