Report on the diversity of crustaceans and mollusks. Diversity of crustaceans, their role in nature and human life. Number of walking legs of cancer

Diversity and importance of crustaceans

Variety of crustaceans

Decapods. This group includes crayfish, as well as large sea crayfish - lobster (weighing up to 15 kg) and lobsters(they don't have pincers). Lobsters hide in crevices and burrows during the day, and go out in search of food at night. With a large and powerful claw, they easily split the shells of mollusks and snails. With another claw, smaller, grasping, they pull out the soft body of the victim and eat it. On average, the length of the lobster is 25 cm, and the weight is 500 g. Giant specimens are also known - over 80 cm.

Unlike the lobster, the spiny lobster has a harder shell - colored bright, reddish brown and thickly studded with spines. The spiny lobster also has long antennae, but there are no claws on the pectoral legs.

shrimps . Some of them move along the bottom, others actively swim in the water column with the help of abdominal legs.

This squad includes hermit crabs . They have a soft, unsegmented abdomen. Hermit crabs hide from enemies in the empty shells of sea snails, all the time carrying the shell with them, and in case of danger, completely hiding in it, covering the entrance with a highly developed claw. A symbiosis of a hermit crab with an anemone is known, which is attached by the sole to its shell-shelter. With its stinging cells, anemone protects itself and cancer from enemies, using, in turn, the remnants of cancer food.

The ten-legged crayfish include crabs . They have a wide but short cephalothoracic shell, a very short abdomen bent under the cephalothorax. Ahead - short antennae. Crabs usually move sideways. Many crabs are able to live on land (in a humid tropical climate).

leaf-footed, or Branched. Small crustaceans well-known to aquarists belong to this order - daphnia about 3-5 mm long. They live in small reservoirs - puddles, ponds, lakes. The entire body (with the exception of the head) of Daphnia is enclosed in a transparent chitinous shell-shell. Through the chitinous covers, a large complex eye and constantly working pectoral legs are visible, which ensure the flow of water under the shell. Daphnia has large, branched antennae. Waving them, she jumps in the water. Therefore, Daphnia is sometimes called "water fleas". Daphnia feed on protozoa, bacteria, unicellular algae located in the water column.

Equinopods. The detachment includes, in addition to other representatives, a small land animal - woodlice . It lives in damp places, such as under stones, in cellars and cellars. The woodlouse living in the ground-air environment breathes atmospheric air with the help of modified gills - pockets that are located on the abdominal legs. Therefore, it can only live in a humid environment, and in dry air, woodlice die. A small crustacean lives in fresh water, vaguely resembling a wood lice, - water donkey.

Diverse. This detachment consists of small (up to several centimeters) crustaceans swimming on their side, for which they are called amphipods. Using different legs, crustaceans can swim, walk along the bottom of reservoirs and along the wet soil of the coast, and also jump.

Barnacles. Representatives of this order are small crustaceans, in adulthood leading an attached lifestyle, for example sea ​​acorns and sea ​​ducks . They live in the sea. Their whole body is covered with a calcareous shell-house. Most often, the shell is attached to stones, crab shells, the bottoms of ships, and whale skin. Barnacles catch their prey (small planktonic organisms) with the help of long pectoral legs that protrude from the shell and quickly retract.

Significance of crustaceans

People use crustaceans for food, crabs, crayfish, lobsters, lobsters, shrimp, krill, etc. serve as an object of fishing. Fishing for decapods in the world reaches almost 700 thousand tons per year. They are highly valued for their tasty and nutritious claw and belly meat.

Interactive lesson simulator (Go through all the pages of the lesson and complete all the tasks)

Topic: Diversity of crustaceans, their role in nature and human life.

Target: consider the diversity of crustaceans, their role in nature and human life.
Exercise:
To get acquainted with various types of crustaceans, their structural features, habitat.
Discuss the classification of crustaceans.
Determine the importance of crustaceans in nature and human life.
Have a creative and interesting time

Basic concepts: orders Decapods, Equopods, Branched mustaches, Copepods, Leaf-legs, Carpoeds.
Equipment and materials: posters with the image of crustaceans, handout for student work, biology textbook for grade 8, diagrams, drawings, tables, multimedia board, videos, presentation
Form of organization of educational activities: cool lesson.
Lesson type: assimilation of new knowledge.
During the classes

I .Organizing time . Greeting participants. Announcement of the topic and purpose of the lesson. Good day everyone! I'm glad to see everyone at our lesson
II Actualization of basic knowledge and skills of students.
1) Brainstorming method
1. What departments does the cancer body have? (cephalothorax and abdomen).
2. How many pairs of walking legs does cancer have? (five)
3. What is the shape of the cancer heart? (Forms of a five-pointed pouch)
4. In what part of the cancer body are the excretory ducts located?
glands? (On the head)
5. How do crayfish reproduce? (Spawn throwing)
6. Where do crayfish winter? (In the hole)
7. How long do crayfish live? (20-30 years old)
8. How many times a year does crayfish shed? (1-2 times)
9. Cancer respiratory organs. (Gills)
10. Organs of smell of cancer. (Long mustache)
11. Circulatory system of cancer. (Open)
12. Digestive system of cancer. (Food is digested in the stomach, which consists of two sections)

2) Make a logical chain "Digestive system of crayfish"

Mouth → pharynx→ esophagus→ stomach → intestines → anus

III . Motivation of educational and cognitive activity of students

... So many legs, so many vehicles - and all this in order to move backwards! F.Krivin

People say it moves backwards like a cancer. How can this be explained? The peculiar appearance of our new familiar cancer led to a well-known misunderstanding where his eyes are and why, when moving, he crawls not forward, but backs up. This misunderstanding contributed to the origin of the original legend of why cancer eyes were in the wrong place.

Cancer all the time asked God that the Lord would give him such huge eyes, like an ox. The Lord gave him small eyes. “They can only be attached from behind,” said the offended crayfish. The Lord left the cancer with small eyes, but made it move forward with its tail, and it turned out as if the eyes of the cancer were behind.

Problem questions: Do you think cancer has relatives? Do they look like crayfish known to us? Where can they be found? What they are and who they are, today we will learn in the lesson. So, the topic of our lesson...
slide 1
Topic: Diversity of crustaceans, their role in nature and human life.
Purpose: to consider the diversity of crustaceans, their role in nature and human life.
slide 2,3,4 Task: To get acquainted with various types of crustaceans, their structural features, habitat. Consider the classification of crustaceans. Determine the importance of crustaceans in nature and human life. Have a creative and fun time.

IV. Perception and assimilation by students of new material.
Slide number 5,6,7

There are more than 50 thousand crustaceans in the world, which can be found where you do not even expect. So, we are going on a virtual journey into the world of crustaceans. The class was previously divided into four groups. Consultants were selected from each group. Each group was given a task. Prepare a presentation. Determine the features of the structure and life of representatives of a particular detachment. Their importance in ecosystems. 4 groups: 1) squad Decapods; 2) detachment Branched mustaches; 3) orders Leaf-footed, Copefoot; 4) detachments of Equinopods, Karpoeds
Today you and I, a group of researchers, decided to find out everything about the representatives of the Crustacean class: how many there are, where they live and what they are. To do this, we will make a short trip, during which we will study the representatives of crustaceans.

Slides #8-12Squad Decapods.
The most famous unit is the Decapods. The body (length 0.3-80 cm) of various shapes, is divided into the cephalothorax and abdomen, on the head there are 2 pairs of antennae and eyes, they have 5 pairs of walking legs. Several species of hermit crabs live in the Black Sea. Young crustaceans that have just hatched from eggs find gastropods with shells of the appropriate size, kill and eat the host, and hide their abdomen in an empty shell.
And now look at this amazing instance - the invisible crab. Invisible - because it is almost impossible to see him among the algae. This lean, long-legged crab is a master of disguise. He carefully sits small bushes of algae on his shell. So it wanders unnoticed in its "camouflage coat". Shrimps, common in all seas and oceans, are found in some fresh water bodies. The greatest species diversity is in tropical seas. They are found in the Black and Azov Seas.
Paleontologists have discovered the fossilized remains of a shrimp that lived on the planet about 360 million years ago. Thus, this find became the oldest among the fossil species of decapods.

Slide #13-14Branched mustache squad
The group of ancient and primitive crustaceans has about 1500 species. The body (length 0.1-10 mm) is divided into the head and torso, partially or completely, covered with a bicuspid chitinous shield. Antenules small, antennae (antennae) well developed, biramous with setae, used for swimming. They are distributed mainly in fresh water bodies. Representatives of the series are daphnia. Their dimensions are very small: the body (1-3 mm) of Daphnia is enclosed in a translucent bivalve shell. Daphnia swim with the help of the second pair of antennae, spasmodically (for this they are also called "water fleas"). Two complex and one simple eyes are located on their head. The food is filtration. Daphnia play an important role in the biocenoses of fresh water, because it is the main fodder base of many
aquatic organisms, it is aquarium fish food, it is the object of study.

Slide #15 Order Leaf-footed The body of these large crayfish (up to 5 cm long) is covered with a large shield.
Shieldfish usually live in small temporary pools, swimming almost all the time with their ventral side down. However, a lack of oxygen can cause them to swim on their backs near the surface of the water, as shields breathe using gills on their legs. They are omnivores. They consume not only plankton, but also large prey, including worms, midge larvae, and even weak tadpoles.
Shields live in temporary reservoirs. When the pools dry up during certain times of the year, in the absence of rain, the adults die during this drought, and the eggs remain dormant (up to 9 years) until the rains fill the pools again, allowing them to hatch. Dried eggs of shield bugs are easily carried by the wind, this ensures the spread of the species.

Slide №19-21
Significance in crustacean ecosystems
The existence of almost all fish, both marine and freshwater, is largely dependent on crustaceans. For the giants of the sea - toothless whales, crustaceans serve as the main food.
Crustaceans play a very important role in the economy of nature. Organic matter in water bodies is created mainly due to the vital activity of microscopic algae. The crustaceans eat these algae and are in turn eaten by the fish. . On the other hand, they use huge masses of dead aquatic animals for food, thus ensuring the purification of the reservoir.
Many crustaceans are directly used by humans as valuable food products. In many countries, the fishery of shrimp, crabs, lobsters, lobsters and other edible species is developed. Recently, successful experiments have been carried out on the use of marine planktonic crustaceans for the extraction of vitamins, fats and other important substances. Some types of crustaceans necessary for feeding young fish are bred at the fisheries.

Slide #24-28.
It is interesting!
The largest of all crustaceans (but not the heaviest in weight) is considered to be the "giant sea spider", which is called the "crab on stilts". It is found in deep water locations on the southeast coast of Japan. Adult representatives of this species usually measure 254mm by 305mm, and the size of their claws ranges from 2.43 to 2.74m.

A rather interesting event took place in Australia: the world's largest crab weighing 6.8 kg was caught off the coast of this mainland. The width of this only, at the moment, specimen reaches 38 cm.
Unusual in appearance, but at the same time, a beautiful crustacean monster got its name because of its huge size. tasmanian king crab. And immediately there were societies that wanted to get this copy of the crab - the Sea Life British Aquarium in Weymouth bought it for $ 5,000, and now the largest crab in the world is a valuable exhibit in the aquarium.
The largest among lobsters and the heaviest among crustaceans is the American lobster (Homarus amerikanus). On February 11, 1977, a lobster weighing 20.14 kg and a length of 1.06 m was caught in the New Animal area, Canada. The lobster was later sold to a New York restaurant owner.
A British expedition discovered the largest shrimp in the world in the waters of the Pacific Ocean, off the coast of New Zealand.
The length of this largest representative of crustaceans in its form was as much as 28 centimeters, while ordinary shrimp do not reach a length of more than 2-3 centimeters.

The smallest among crustaceans is considered to be a water flea (of the genus Alonella) measuring less than 0.25 mm in length. She lives in UK waters.
the smallest known lobster is Homarus capensis, which lives in southern Africa. Its total length is only 10-12cm.
the smallest crabs in the world - the so-called "pea". Some species of these crabs have a shell size of 6.3 mm.
Long-livers among crustaceans is the American lobster (Homarus amerukanus). The largest representatives of this species live up to 50 years.

Slides #29-31
folk wisdom

Whom does grief color?
Not a blacksmith, but with tongs.
In order not to get into trouble, he keeps scissors in the water.
Who has a mustache longer than their legs?
Not an egg, but in a shell, not a cat, but a mustachioed one.
Sitting on the rocks, moving his mustache,

And go for a walk - backwards.

Crawling backwards, backwards

Everything underwater lacks claws
Proverbs and sayings
Only crayfish are moving backwards.
One cancer paints grief.
The terrible cancer is behind the eyes.
A miracle, not crayfish: they climb into the bag themselves.
Then it will be like a crayfish whistles in a pond.
On lack of fish and cancer fish.
Went to the bottom of the crayfish to catch.
It doesn't matter to the raku in which pot it is boiled.
God had mercy on Cancer and gave him eyes from behind.
The cancer took pity on the frog and tore out its eyes.

While the members of one team report on a particular order of crustaceans, the others write down in a table all the species they hear about or see.

Why are representatives of the class Crustaceans combined into one class?
2. Game "Field of Wonders"
This copepod got its name in honor of the mythical one-eyed giant.
What is it called?

(Cyclops)
On the desk:
3. Find the "extra" animal among those named:
crayfish, crab, daphnia, lobster, shrimps, lobsters.
4. Decipher which crustaceans are hiding behind jumbled letters:
tsykrimo; windmills; tiguslan
(louse) (shrimp) (lobster)

5. "Find out the name", take a set of letters and make an anagram in a group, others guess

POIDROCO
MORA
TYGUSLAN
NIIDAF
KBAR
KRIMOTSY
WINDCRACKS
TISHCHIN

7. The basis of the integument of arthropods is organic matter
a) chitin; b) murein; c) starch; d) cellulose.

8. Arthropod body cavity:
a) mixed; b) parenchyma; c) secondary; d) primary.

9. Nervous system of arthropods:
a) nodal; b) diffuse; c) stem; d) it looks like a tube.

10. Organs of excretion of crustaceans:
a) kidney b) metanephridia; c) green glands; d) malpilgian vessels.

11. Respiratory organs of crustaceans:
a) gills; b) trachea; c) lung bags; d) gills and lung sacs.

12. Mark the number of pairs of limbs located on the head of the crayfish:
a) three; b) five; at seven o'clock; d) nine.

VII. Summary of the lesson.
- What are your impressions of the lesson?
- What did you like the most?
- What interesting things did you find out?
- What methods would you like to use in the next lesson?
VIII. Assessment of students.
At the beginning of the lesson, students are given tokens for each group; the commander, with correct answers, gives out tokens to a certain student.
At the end of the lesson, according to the number of tokens that the students received, marks are given.

IX. Homework .
Work through paragraph 20
Write an essay-miniature on the topic "The fate of crustaceans in the future"

Sections: Biology

Purpose: To acquaint students with the diversity of lower and higher crustaceans, habitat, consider their importance in aquatic biocenoses; continue to develop skills to justify your answer.

Equipment: Collections of crustaceans, tables depicting crayfish and a variety of crustaceans, drawings in the textbook.

I Checking knowledge and skills.

1. Characteristic signs of the type of arthropods, structural features, vital activity of crustaceans on the example of crayfish. (foyer of the zoological museum)
2. Historical development of arthropods. (foyer of the zoological museum)

II. Learning new material.

1. Diversity of crustaceans colonization of water bodies: seas and oceans.

A) lower crustaceans: cyclops, daphnia, brine shrimp, sea acorn, sea ducks.

Hall 1 Crumbs living in water (brine shrimp, daphnia, cyclops)

Hall 2 Sitting crustaceans (sea ducks),

sea ​​acorns)

Hall 3 Life and customs of woodlice

B) Higher crustaceans: river and sea crayfish, crabs, shrimps, lobsters, lobsters.

Hall 5 Hermit crab

The role of crustaceans in biogeocenoses

Hall 6 The chain of life in the sea.

III. Fixing:

1. Crossword
2. Test

IV. Homework pp. 148-149

During the classes

Foyer of the Zoological Museum of Crustaceans

Arthropods are crayfish, crabs, spiders, scorpions, centipedes, insects. There are a great many of them on earth. There are about 3 million species of arthropods alone.

The very name of the type of these animals shows that their legs are jointed. Each segment is connected to other segments, and to the body by a special movable joint. They walk and run, one might say, on numerous levers. The muscles that move the legs and other parts of the body are not attached outside the skeleton, but inside it, that is, inside the chitinous shell that covers the entire body of arthropods. Since the shell is located on top of the rest of the body of the animal, it is strong and, having formed, does not increase in size, therefore arthropods can grow only during molting when they shed the old shell, and the new one is still soft and stretchable. Therefore, their growth can be said to be spasmodic. Crayfish changes only once a year.

And here's another difference between arthropods - all their muscles are striated. And as you know, it has more powerful and faster contractions. The striated muscles of arthropods provide those high-speed movements that, for example, insect wings are capable of.

Arthropods have a fairly well-developed heart, but the circulatory system is open. Therefore, their blood is often called hemolymph, which gives a more accurate definition of the generated marine fluid that is distilled through their blood vessels and body cavities. In crustaceans, for example, in lobsters, a special pigment is dissolved in the blood - hemocyanin, something like hemoglobin, which carries oxygen to the cells. But hemoglobin is red in color, and hemocyanin is bluish in color, because it contains not iron, but copper. By the way. Some crustaceans also have hemoglobin.

Arthropods are an ancient group of organisms. Many classes of them already lived in the Cambrian. They originated in the Decembirian from some animals close to annelids. Trilobites were the first to form their typical appearance. In our time, arthropods have populated everything from the Arctic to Antarctica.

The fact that arthropods have passed from annelids is proved by the presence of many structural features common to these types of animal:

1. body segmentation
2. structures of the nervous system in the form of a ventral nerve cord
3. the similarity of the circulatory system with the main vessel lying on the dorsal side of the body.
4. The presence of modified mtanefridia in some arthropods.

Hall 1 “Crumbs living in water”.

There is a crustacean in the world - the entire length of its body is 1.5 cm, which can only live in salt water, where any other animal inevitably dies. The name of this amazing crustacean is Artemia salima.

Artemia salima lives in lakes, estuaries and bays in Europe, Asia, America, Africa, where the salt saturation of water is 23%. It withstands high salinity, and dies at lower salinity. It belongs to the branchial crustaceans.

And gastropods are the most primitive in the class of crustaceans. Their legs are partially turned into gills. But they have blades with which they row and drive food into their mouths.

The gastropods always swim with their backs down. But if you conduct an experiment and illuminate, for example, an aquarium in which Artemia salina is located, with a strong lamp from below, the crustaceans turn over and swim with their backs up.

Studying the Sivash Bay, the Soviet scientist V.P. Vorobyov calculated that in one cubic meter of water there are 13.6 g of brine shrimp, which means that there are 14.8 thousand tons of them in the entire bay. The bay of Kara-Bogaz-Gol was not yet separated from the sea (30%), had a reddish tint to the water, due to the mass of crustaceans that swarmed in the water. Now this bay has become more salty and the crustaceans in it have died.

Artemia feed on diatoms and green algae, which have adapted to live in “oversalted” water. With a lack of algae, they disturb the silt, and, swarming in it, fish out bacteria from it. Here are the Indians living on the shores of the Great Salt Lake in Utah, they ate both in winter and summer mainly brine shrimp.

Daphnia or water fleas are well known to all aquarium lovers. These tiny crustaceans are the predominant component of freshwater plankton and fill the ponds, burrowing in such a multitude that the water acquires a brownish tint.

The body of Daphnia is enclosed in a bivalve shell, from which only the head and second antennae, or, simply speaking, antennae, stick out. They are not simple, but branched, therefore they are referred to the suborder of branchy mustachioed crustaceans.

Daphnia legs are partially turned into gills. They also drive food into the mouth, but do not take part in the movement. Daphnia jumps in the water like a flea, sharply waving its branched antennae.

Daphnia feed, filtering out detritus, small animals and algae, which are no larger than 0.02 mm, by smoothly working pectoral legs. the most solid is daphnia magna half a centimeter long, all others are smaller. They eat daphnia and flagellates, but the main food is bacteria. One water flea eats from 5 to 40 million of all kinds of bacteria per day. Daphnia are hermaphrodites, although they can reproduce sexually if necessary. But this happens only when there is a big death. In this case, males hatch from eggs. They are dwarfs compared to females, but nevertheless they fertilize females very actively. After that, the eggs are covered with a thick cuticle, for example, it is easier for such eggs to overwinter. Or the wind carries them with dust, settling them in the nearest water bodies.

They got their name in honor of the mythical one-eyed giant with whom the cunning Odysseus dealt, for the reason that these crustaceans also have only one eye on their foreheads. Unlike brine shrimp and daphnia, they have no gills on their legs or anywhere else. They breathe through the entire surface of the body. There is no heart, no circulatory system: "The abdominal fluid is set in motion by the contractions of the intestines."

When swimming, the cyclops “rows” with four pairs of pectoral legs. It will make, by waving them, a jerk forward or upward, and then soars in the water on its spread mustaches, like an eagle on outstretched wings. He can swim on his back, and do “Dead Loops”, and dive with his head.

In general, the inexhaustible cascade of maneuvers performed by the cyclops is very similar to aerobatics.

Cyclopes are predators and, moreover, very dangerous for small animals: they cope with worms and mosquito larvae, moreover, larger than themselves. They do not shy away from cannibalism.

Cyclops also show a kind of concern for offspring. The female carries fertilized eggs on the sides of the tail, and the eggs are glued together in two lumps until the larvae hatch from them.

Hall 2 - Crustaceans, seated.

There are crayfish that, like a sponge, cannot budge. Only their larvae swim. And as the larva sits on the bottom, clings to it with its antennae, turns into an adult cancer, and sits all its life on a stone, rock, on a mollusk shell, on a crab shell, it happens on the skin of whales, and sharks, and even on the teeth of a sperm whale, in general, at the place to which the larva is attached. He sits and moves his mustache.

And the mustache of cancer is a magnificent fan. He then scatters it, then folds it in a bunch, driving water into his mouth, and with it any plankton (but not larger than 1 mm)

These animals, therefore, are called barnacles. They live in shells with lids made of calcareous plates. Those of them, in which the shells are attached to some object directly with their wide bases, are called sea acorns. And if a lime house sits on a stalk with its other end stuck to the substrate, then these will be sea ducks.

Sea acorns usually settle close to each other, so that they form dense fouling of stones and rocks in the tidal zone and even above the water level, in this case being content with the meager food that the surf brings to them.

Sea acorns cause great damage to the surfaces of ship hulls. Up to 45 thousand larvae sometimes settle on 1m 2 of the bottom of the ship. If we take into account that during the day they increase their height by 1 mm, then it is easy to understand that due to sea acorns, good streamlining is lost, which reduces its normal speed by a third. We have to bring the ships to the docks and clean them from fouling.

Whales, in particular the gray whale, usually carry thousands of passengers. Marine crustaceans - sea ducks no larger than a coin - need a solid base to which they can attach. The huge surface of the whale's body is just as good for them as the rock or the bottom of the ship. Sea ducks feed on tiny organisms, sucking and straining them out of the water. The patterns of these shells on the whale's back help whalers recognize individual individuals.

Hall 3 - the life and customs of wood lice.

Woodlice are the only isopods that have mastered the living space of land of all latitudes and climates.

True, there are some primitive woodlice that have not yet completely parted with the habits of their ancestors, have not gone far from the sea - they live on its shores. They even know how to swim, they even conducted experiments where they were kept under water for 80 days and they did not die. All other wood lice would have “choked” long ago if they were subjected to such an experiment.

Land woodlice try to keep all the same in wet places. During the day, they hide from the sun under stones, buried in the ground, or in burrows dug by themselves or strangers, looking for shelter even in anthills. At night, they crawl out of their shelters and gnaw on plants, replenishing their thirsty body with moisture.

Desert woodlice among arthropods. Perhaps one of the most numerous inhabitants of the loess deserts and, apparently, are of no small importance in the life of the desert. These wood lice are constantly looking for new places suitable for existence. They crawl slowly, covering about two meters in a minute. This is when it is relatively warm +10 +15 0 s in the shade.

Desert woodlice do not live alone, but always in colonies, in which sometimes there are several million families. Caring for alien offspring belonging to one's own species is one of the most interesting features of the biology of woodlice. It has no analogy among other crustaceans.

River and sea crayfish, crabs and shrimps are representatives of the order of decapod crayfish, or decanods. The order is extensive: it contains 8500 species. It got its name for the reason that the animals representing it walk on ten pectoral legs, and the first pair of them in many is transformed by nature into powerful claws. Decapods also have gills on the bases of the thoracic legs, and their females attach eggs to the abdominal legs, and only a few shrimp do not carry eggs on themselves, but sweep it directly into the water. The head and chest are covered with a monolithic cephalothoracic shield - a carapace. In crayfish, it looks like a warrior's cuirass and immediately catches the eye. Behind him stretches the abdomen, already dressed with separate plates, which ends with a “tail” (telson).

Huge crayfish live off the coast of Africa, America and Europe, these are lobsters and spiny lobsters.

The European lobster is up to 50 cm long and weighs 11 kg. American lobster - up to 60 cm long, weighing up to 15 kg. On the front pair of walking legs of the lobster are powerful claws. One of them is stronger - crushing, the other - cutting. Lobsters don't have claws. Within Russia, the European lobster is found in the Black Sea on rocky and pebbly soils at a depth of 30-80 m. During the day, the lobster hides among the stones, and at night it hunts for mollusks, worms, and shrimps. It grows slowly, reaching sexual maturity only in the sixth year. The female lays about 32 thousand eggs on the abdominal legs, from which floating larvae emerge after a year.

Lobsters are smaller in size than lobsters (but there were cases when they met lobsters up to 75 cm long.) These crayfish live at shallow depths along the coasts of Europe and Africa in the Mediterranean Sea, AS WELL AS IN the Pacific, Indian and Atlantic oceans. Spiny lobsters have long antennae, and their chest is covered with numerous shields. Unlike lobsters, lobsters do not have claws on their front legs. Interestingly, with the help of waving antennae - antennas that rub their base against the front edge of the shell, lobsters make a loud sound.

Lobsters and lobsters are considered a food delicacy and are caught in large numbers. Only off the coast of Europe and America, about 1000 tons of these crayfish are mined annually, and off the coast of Cuba - about 8000 tons.

Shrimps belong to the swimming suborder (natancia), while lobsters and lobsters are crawling suborder (rentancia). Slope shrimp will settle in sponges, because. they hide in them.

Some shrimp often find safe shelter under jellyfish colonies, between the tentacles of sea anemones, in the cups of sea lilies, and also in sponges.

For the most part, shrimp are free-floating inhabitants of marine, brackish and fresh waters.

Some of them are hermaphrodites (an exception among decapods). In youth, when it turns from larvae into adults, they are males. After living for two years, they are reborn as females. Shrimps are even able to change their color to match the color of the bottom.

Kamchatka crab, its life is peculiar. It inhabits the Japanese, Okhotsk, Bering seas. The carapace of the male of this species is on average 16 cm wide, and in the Gulf of Alaska - 28 cm.

The distance between the ends of the average walking legs of such large individuals is 1.5 m, and the total body weight is up to 7 kg. The Kamchatka crab, although decapodous, has only four pairs of legs “in use”. He hides one pair of legs under the shell and cleans the gills with them. First pair of legs with claws. The right claw is large and strong. With it, the crab opens the shells of mussels, breaks the shells of sea urchins. With his left claw, he crushes food and sends it to his mouth.

King crabs are real travelers, and every year they repeat the same route. Crabs hibernate at depths up to 250 meters. In spring they return to the coast to molt and breed. In the fall they go deeper again. The female lays 20,000 to 300,000 eggs and carries them, like a cancer female, on her abdominal legs for 11.5 months.

In the crabs fishery, males are harvested (it is forbidden to harvest females) up to 13 cm long or more. The right claw with its segments is the most valuable product of the crab industry. Crabs are processed on floating plants. Shells and entrails are processed into excellent fertilizer.

Hall 5 Cancer is a hermit.

More than two thousand years ago, the father of zoology, the great Aristotle, drew attention to strange crayfish.

Hermit crabs' partners are anemones, or sea anemones, which live in the sea everywhere, such as in coral reefs where animals live together or on other animals. So it is easier for them to get food or find protection.

The hermit crab does not have its own shell, so it lives inside old sea shells. On coral reefs, sea anemones share a home with hermit crabs. Anemones with their burning tentacles protect themselves and hermit crabs. And those, in turn, supply a lot of food residues that eat up anemones.

A higher stage in the development of symbiosis is represented by the “friendship” of Prideaux crayfish and adamsia sea anemones.

Adamsia, if separated from cancer, dies in 2-3 months, and Prido's cancer dies even faster: for the first time, he becomes a victim of the greed of predatory fish and an octopus. Cancer, after all, is not protected now by the stinging batteries of sea anemones.

Few people have ever seen Prideaux's crab without sea anemones. The anemone itself also lives without cancer only at a young age. Sitting on a stone is a kind of pink bud the size of a thimble. No one has ever met large adamsias in the sea, except on the shells of Prideaux. Therefore, it is unknown to zoologists whether these anemones reach full maturity without the help of cancer, leading a free lifestyle.

Cancer feels the anemone with its antennae, and if it is wrapped in a rag, it will not be mistaken either: it will distinguish its action from someone else's. He probably smells it. He carefully takes her claws at the very bottom, at the sole, so as not to damage her, and puts her on the sink. Actinia does not sting cancer. Although experiments have shown that hermit crabs are not susceptible to sea anemone poison. A substance is formed in their blood that neutralizes this poison.

Hall 6 The chain of life in the sea.

Life in the sea begins with phytoplankton - the smallest algae. It is they who create the primary products - biomass, on the basis of which almost all other inhabitants of the sea exist.

Not visible to simple gas, a small green cell, hovering near the surface of the sea, is the first to capture the energy of the sun, and during photosynthesis converts it into nutritious organic substances. During one year, about 500 million tons of organic matter are formed in the World Ocean. The food chain starts with phytoplankton.

Its next link is zooplankton - these are microscopic animals that live in the sea water and feed on algae. Mostly they are crustaceans. Zooplankton are eaten by small fish forming another link. In turn, they can become prey for larger fish. Birds or animals can become the next link. Interestingly, the total mass of living beings in each subsequent link is about 10 times less than in the previous one.

At the end of our tour, we can conclude:

That the world of crustaceans is diverse and beautiful, which in turn are the second link in the food chain in rivers, lakes, seas and oceans.

V. Consolidation.

1. Test.
2. Make a food chain including representatives of crustaceans.
3. Compose a crossword.

VI. Homework pp. 148-149.

About 30,000 species of crustaceans are known. Among them there are small crustaceans 2-5 mm long. These are daphnia and cyclops. They float in the water.

Figure: variety of crustaceans

Organisms floating in water, such as daphnia and cyclops, are called plankton. Daphnia and cyclops live both in fresh waters and in the seas. They make up a significant part of the plankton and serve as food for various fish. In pond fish farms, they are specially bred for feeding fry.

Decapod crayfish, which also includes river crayfish, got their name from the number of walking pectoral legs. This also includes shrimp, crabs, lobsters and lobsters that live in the seas. These are valuable commercial crustaceans, which are mined for meat. There are about 10,000 known species. Many crustaceans serve as a favorite food for fish and toothless whales.

General characteristics of crustaceans

Crustaceans are gill-breathing aquatic arthropods that differ from other arthropods in having two pairs of antennae and biramous limbs. Most crustaceans have a cephalothorax and an abdomen. Respiratory organs - gills, which are outgrowths of the limbs.

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Lesson topic: "Crustaceans, their diversity, common features and significance"

The objectives of the lesson: to study the diversity of crustaceans, to get acquainted with the features of their structure, to highlight common features, to consolidate knowledge about the features of the external and internal structure of crustaceans, to determine the meaning of crustaceans in nature and human life, to form the ability to analyze, concretize, draw conclusions, generalize and systematize the material, develop the processes of memory, attention, imagination.

In the last lesson, we got acquainted with the structure of crayfish, which belongs to the class Crustacea. This class includes more than 30 thousand species from 1 mm to 1 m. Among them, lower and higher crustaceans are distinguished. Today we will get acquainted with some units of this class. Crayfish

Classification of Crustacea Orders LEAF PEDAL CONEPODS ISALOPEDS DIFFERENT DECAPS lower higher Class Crustacea TYPE ARthropod daphnia shield cyclops Sea Duck Sea acorn Woodlice Water donkey amphipods Crayfish Lobster Spiny lobster Crabs Shrimp

Lower crustaceans Lower crustaceans are several orders of crustaceans whose representatives lack ventral legs. A) Detachment Leaf-legged - representatives of this detachment have legs flattened like a leaf. daphnia shield

B) Order Copepods - these are small crustaceans that row with their pectoral legs like oars. Cyclops are ordinary copepods of our reservoirs. They got their name for an unpaired simple eye located on the forehead. Cyclops serve as intermediate hosts for broad tapeworm and guinea worm. They use their antennae for locomotion. Cyclops can perform complex movements - "dead loops" like a fighter plane.

C) Order Barnacles - representatives of this order lead an attached lifestyle and live in multi-valve calcareous shells. Their head and abdomen are greatly reduced, and the thoracic region is better preserved from the whole body. Two-branched long legs turn into a filtering apparatus, with the help of which barnacles get their own food ... Sea ducks

sea ​​acorns

Higher crustaceans Representatives of higher crayfish have a constant number of head, thoracic and abdominal segments, the latter have abdominal legs. A) Detachment Equinopods Outwardly, their legs seem to be the same. In fresh waters there is a water donkey, which crawls along the bottom on thin legs. On the head of a donkey there are 8 simple eyes. water donkey

Woodlice are terrestrial isopods. Woodlice live in damp places - in cellars, basements, under stones and lagging bark. They lead a nocturnal lifestyle. All segments of the thorax and abdomen remain free and clearly visible. Woodlice breathe moist air with the help of modified gills. woodlouse

B) Order Diverse - these are crayfish that have different limbs for movement. They are often called amphipods, because. moving around lying on their side. amphipod

C) Detachment Decapods - in representatives of this detachment, the pectoral limbs turn into powerful walking legs, of which there are 5 pairs. With their help, they move along the bottom of reservoirs, and small abdominal ones are used for swimming and bearing offspring. They mainly live in the seas. There are about 9 thousand of them. This is the same detachment where the crayfish belongs.

Such different decapod crayfish Crayfish Crayfish (boiled) Mantis crab

Omar Langust

Hairy crab King crab Blue crab