Environment-formers of biocenoses of coral reefs and atolls.
Formers of calcareous rocks.
They gave rise to the first three-layered animals.
They are a link in the food chain of aquatic biocenoses,
Some people eat (aurelium and rapilleme) and use them as decorations.
Some are poisonous and dangerous to humans and animals (jellyfish cross, cornet, etc.).
New concepts and terms: radial symmetry, ectoderm, endoderm, mesoglea, intestinal cavity, ganglion, stinging cells, diffuse nervous system, cavity digestion, statocyst, rhopalia, budding, regeneration, planula, jet propulsion
Questions for consolidation:
- What are the differences between Unicellular and Multicellular animals? Why are they combined into one kingdom?
- What are the advantages of Multicellular animals over Unicellular animals? What are the disadvantages?
- How does the hydra reflex work? Can the release of a stinging thread be attributed to reflexes? Explain your answer.
- What types of digestion do coelenterates have, and by what cells are they carried out?
- What cells are characteristic only of coelenterates, what are the features of their structure and function?
- What life forms are found in coelenterates, and how do generations alternate?
- Why are corals sometimes mistaken for plants and called " sea flowers"? What are the fundamental differences between Coral polyps and plant organisms?
Type Flatworms
Initial level of knowledge:
Response Plan:
General characteristics of flatworms
External and internal structure of flatworms
Reproduction of Flatworms
Classification of Flatworms, variety of species
Peculiarities of the structure and development of worms of the Ciliate class using the example of the Milk planaria
Features of the structure and development of worms of the class Flukes using the example of the Liver fluke
Features of the structure and development of worms of the Tapeworm class using the example of the Bull tapeworm and others.
General characteristics of flatworms
Number of species: about 25 thousand.
Habitat: They live everywhere in humid environments, including the tissues and organs of other animals.
Structure: Flatworms are the first multicellular animals in which, during the course of evolution, bilateral symmetry, three-layer structure, and real organs and tissues appeared.
Bilateral (two-sided) symmetry - this means that an imaginary axis of symmetry can be drawn through the animal’s body, with the right side of the body being a mirror image of the left.
During embryonic development in three-layered animals, three layers of cells are laid down: the outer one is the ectoderm, the middle one is the mesoderm, and the inner one is the endoderm. From each layer certain organs and tissues develop:
are formed from the ectoderm skin(epithelium) and nervous system;
from the mesoderm - muscle and connective tissue, reproductive tissue, excretory system;
from the endoderm - the digestive system.
In flatworms, the body is flattened in the dorso-abdominal direction, there is no body cavity, the space between the internal organs is filled with mesoderm cells (parenchyma).
Digestive system includes the mouth, pharynx and blind intestine. Absorption of food and excretion of undigested residues occurs through the mouth. U tapeworms The digestive system is completely absent; they absorb nutrients over the entire surface of the body, being in the intestines of the host.
Excretory organs – protonephridia. They consist of thin branching tubules, at one end of which there are star-shaped fiery (ciliating) cells embedded in the parenchyma. A bunch of cilia (flickering flame) extends inside these cells, the movement of which resembles the flickering of a flame (hence the name of the cells). Flame cells capture liquid decay products from the parenchyma, and cilia drive them into the tubule. The tubules open on the surface of the body as an excretory pore, through which waste products are removed from the body.
Nervous system of the scalene type (orthogonal). It is formed by a large head paired nerve ganglion (ganglion) and six nerve trunks extending from it: two on the ventral side, two on the dorsal and two on the sides. The nerve trunks are connected to each other by jumpers. Nerves extend from the ganglion and trunks to organs and skin.
Reproduction and development:
Flatworms are hermaphrodites. Sex cells mature in the sex glands (gonads). A hermaphrodite has both male glands - testes, and female glands - ovaries. Fertilization is internal, usually cross-fertilization, i.e. worms exchange seminal fluid.
Class Ciliated Worms
Milk planaria, a small aquatic animal, the adult is ~25 mm long and ~6 mm wide, with a flat, milky white body. At the front end of the body there are two eyes that distinguish light from darkness, as well as a pair of tentacles (chemical sense organs) necessary for searching for food. Planarians move, on the one hand, thanks to the work of the cilia covering their skin, and on the other hand, thanks to the contraction of the muscles of the skin-muscular sac. The space between the muscles and internal organs is filled with parenchyma, in which there are intermediate cells responsible for regeneration and asexual reproduction.
Planarians are predators that feed on small animals. The mouth is located on the ventral side, closer to the middle of the body, from it comes a muscular pharynx, from which three branches of a closed intestine extend. Having captured the victim, the planaria sucks out its contents with its throat. Digestion occurs in the intestines under the action of enzymes (intestinal), and intestinal cells are able to capture and digest pieces of food (intracellular digestion). Undigested food remains are removed through the mouth.
Reproduction and development. Ciliated animals are hermaphrodites. Cross fertilization. Fertilized eggs fall into a cocoon, which the worm lays on underwater objects. Development is direct.
Class Flukes
The fluke feeds on blood and liver cells, sucking food through the oral sucker with the help of a muscular pharynx and esophagus, from there the food enters the branched, blindly closed intestine.
Rice. Development of the liver fluke:
Class Tapeworms
Bull tapeworm is a tapeworm that reaches a length of 4 to 12 meters. The body includes a head with suckers, a neck and a strobila - a band of segments. The youngest segments are located at the neck, the oldest are sacs filled with eggs, located at the posterior end, where they come off one by one.
Reproduction and development. The bovine tapeworm is a hermaphrodite: each of its segments has one ovary and many testes. Both cross-fertilization and self-fertilization are observed. The posterior segments, filled with mature eggs, open and are excreted with feces. Large cattle(intermediate host) can swallow eggs along with grass; in the stomach, microscopic larvae with six hooks emerge from the eggs, which enter the blood through the intestinal wall and are carried throughout the animal’s body and carried into the muscles. Here the six-hooked larva grows and turns into a finna - a vesicle, inside which is the head of the tapeworm with a neck. A person can become infected with finches by eating undercooked or undercooked meat from an infected animal. In the human stomach, a head emerges from the finca and attaches to the intestinal wall. New segments bud from the neck - the worm grows. Bull tapeworm secretes toxic substances, which cause intestinal disorders and anemia in humans.
The development of pork tapeworm has a similar nature; its intermediate host, in addition to pigs and wild boars, can also be humans, then finches develop in its muscles.
The development of a wide tapeworm is accompanied by a change of two intermediate hosts: the first is a crustacean (Cyclops), the second is a fish that ate a crustacean. The definitive host may be a person or a predator that eats the infected fish.
New concepts and terms: mesoderm, skin-muscle sac, tegument, hypodermis, reduction, protonephridia (flame cells), orthogon, strobila, ganglion, gonads, hermaphrodite, direct and indirect development, final and intermediate host, miracidium, cercaria, finna, segment, armed and unarmed tapeworm.
Type Roundworms
Initial level of knowledge:
Response Plan:
General characteristics of Roundworms
Body structure of human roundworm
Reproduction and development of human roundworm
Classification of Roundworms, variety of species
The significance of Roundworms in nature and human life
The importance of coelenterates in nature
Coelenterates live almost everywhere: the surface and depths of the oceans, freshwater bodies, various soils, polar regions and the tropics.
Coelenterates:
- participate in the formation of sea biocenoses;
- increase the biological productivity of water bodies;
- absorb in large quantities suspended organic matter and purify sea water, for example, freshwater hydra is a natural filtrate, purifying water from organic particles, the coral sea anemone polyp feeds on bacteria, algae, and protozoa in the water, performing the function of a filtrate.
Coelenterates are a necessary link in food chains in the World Ocean. They regulate the number of fish and crustaceans. Coral polyps take part in the calcium cycle in nature, and also form sedimentary rocks.
In nature, you can observe amazing symbioses of coelenterates with other organisms.
Example 1
“Cohabitation” of a hermit crab and an adamsia sea anemone. The sea anemone uses the crayfish for movement, receiving food particles from the sand agitated by the crayfish, as well as its food remains. In the person of Adamsia, the hermit crab receives reliable protection from enemies. When changing houses, the crayfish transfers the sea anemone to a new location. Often hermit crabs take Adamsia from their relatives.
Example 2
Symbiosis of sea anemones and clown fish, or amphiprions. The fish clean the sea anemone from food debris and debris and take care of it. The sea anemone eats what is left of the clown fish's prey.
Small shrimps can act as parasites and cleaners. They hide from their enemies in the tentacles of sea anemones. IN difficult relationships Jellyfish are found in nature with other organisms.
For example, the body of golden jellyfish is inhabited by the algae zooxanthella, which gives the jellyfish a yellowish color. The algae use the waste products of the jellyfish as food, and the jellyfish also provides uniform lighting. What benefits algae bring to jellyfish is not completely clear.
Example 3
The larvae of jellyfish cunoctantus and jellyfish kunina attach to the umbrella of other jellyfish, where they reproduce by budding. These jellyfish take food directly from the host’s stomach with their tentacles.
Colonial polyps form coral reefs in shallow waters in tropical seas. Islands of tropical seas - atolls - are formed from ring-shaped reefs. Symbiont algae live in coral polyps.
The importance of coelenterates in human life
Representatives of coelenterates are commercial objects. Salted jellyfish Rhopilema verrucosa and Rhopilema esculenta are used as food (fishing occurs mainly in China and Japan). Jellyfish are first removed poisonous tentacles, then they are salted and dried. Dried jellyfish are used in salads, fried with the addition of cinnamon, pepper, nutmeg, and boiled.
All kinds of art and jewelry are made from coral polyps. Coral branches are used as souvenirs. The most valuable are black and red corals; expensive ones are made from them. jewelry. Nowadays, coral collecting is becoming popular.
Coral limestone is a good building material and is used to make lime. In medicine, hydroid polyps and jellyfish are used
- for the purpose of obtaining biologically active substances;
- as laboratory animals when conducting experiments.
Note 1
Based on the ability of jellyfish to foretell the onset of a storm, the Jellyfish Ear device was created to indicate the approach of a storm, earthquake or storm.
Underwater reserves are often created on coral reefs. Present and Negative influence coelenterates, for example,
- coral polyps form reefs that impede the free movement of ships;
- The poison of some jellyfish is dangerous for humans, for example, the poison of the stinging cells of the Portuguese man of war, which lives in tropical seas, causes not only severe burns, but also disturbances in the rhythm of breathing, heart function, severe pain, for residents northern regions cyanea and sea wasp are dangerous;
- jellyfish and polyps eat fish fry, causing damage to fisheries.
Development of a biology lesson in 7th grade on the topic: “ Diversity of coelenterates, significance in nature, human life».
MBOU secondary school No. 33
Nedorub Marina Vladimirovna
Goal: to study the diversity of coelenterates, to show their role in nature and human life.
Lesson objectives:
- educational: provide knowledge about the diversity of coelenterates; consider the classes of scyphoid and coral polyps; show the significance of polyps in natural communities and for humans;
- developing: continue to develop the skills to work with additional literature, tables, substantiate the features of the organization of coelenterates as lower multicellular organisms, highlight progressive changes in coelenterates, prove relative character fitness, analyze, compare, generalize, draw conclusions, answer questions, work with tests, speak in front of an audience;
- educational: to educate children to respect nature, preserve biological diversity..
Lesson equipment: illustrations of jellyfish, coral polyps; tables of coelenterate diversity; physical map of the hemispheres, multimedia textbook: “Grade 7 Biology”, computer, projector.
Leading concepts: Class Hydroid, class Scyphoid, class Coral polyps, planula,
hydromedusa.
Type of lesson: lesson - travel.
During the classes.
I. Organizing time.
Greetings;
Preparing the audience for work;
Availability of students.
II.The main part of the lesson.
1) Testing students' knowledge.
METHOD: frontal survey
individual conversation (at the blackboard);
working with cards; (3 persons).
Frontal: Answer the questions.
1. Why did the type Coelenterates receive such a name? (these are two-layer multicellular animals with a single body cavity - the intestinal cavity). What functions does the intestinal cavity perform?
Hydra is a sedentary freshwater animal; jellyfish swim quickly in the thickness of sea water. Why are these animals classified as the same type? (intestinal cavity).
Hydra and sea anemone in their own way appearance resemble plants. What signs indicate that these are animals? (method of nutrition).
The general plan of the body structure of a multicellular animal is determined primarily by the nature of the symmetry of its body. Explain what symmetry is. What body symmetry is characteristic of coelenterates?
Through the mouth opening in coelenterates, not only food intake occurs, but also undigested residues are excreted. How can this be explained? (primitive structure).
6.The body of coelenterates consists of many cells. How are coelenterate cells similar? (differentiated). What explains their difference? (performing functions). Why can’t a coelenterate cell exist outside the body? (connected with other cells).
Nerve cells in coelenterates are star-shaped. Communicating with each other through their processes, they form the nervous system. Why is such a nervous system considered primitive? (they are scattered throughout the body).
Protozoa and coelenterates react differently to irritations from external environment. What is their difference? What is a reflex? (in protozoa the body consists of one cell, and in coelenterates there are special nerve cells).
The presence of stinging cells is one of the most characteristic features of coelenterates. What functions do they perform?
The main function of the endoderm is digestive. What features allow it to perform this function?
What is regeneration, what is its role in the life of coelenterates?
Scientists claim that unicellular and multicellular animals are related. Give evidence known to you for this statement.
Jellyfish live in deep sea water. What adaptations allow them to move in this environment and defend themselves from enemies?
Why are aquatic plants placed in an aquarium with hydras?
Why is the hydra considered a predatory animal?
What is the complexity of the organization of coelenterates compared to protozoa?
Individual conversation:
1. Give general characteristics coelenterate.Simultaneously another student at the board determines, using classification units,systematic position of Hydra freshwater .
Talk about the structure of hydroids using the example of freshwater hydra. (Using a table).
What is the internal structure of the hydra?
How does hydra reproduce and develop?
2) Studying new material.
Basic principles of the lesson.
Systematic review of the phylum Coelenterata:
TYPE COELENATE -COELENTERATA
Class I. Hydroid – Hydrozoa
Class II. Scyphoid jellyfish –Scyphozoa
Class III. Coral polyps -Anthozoa
More than two thirds globe covered with water. That's why our planet appears blue from space. The Earth's water space is divided into five huge parts - oceans. They, in turn, are divided into smaller ones - seas. Under the ocean water there is a completely special world. There are deep valleys, huge mountains, forests seaweed and many amazing sea animals. Today in the lesson we will take a trip to the underwater world, where we will meet many coelenterate animals, look at representatives of different classes of coelenterates, study their similarities and differences, as well as the features of their organization and diversity, lifestyle, practical significance.
Work in notebooks:
Subject: TYPE Coelenterate
Class Hydroids Class Scyphoid jellyfish Class Coral polyps
OSO-
BEN-
NOSE-
TI
ORGA-
BOTTOM-
CII
PRE-
STA-
IN AND-
THOSE-
LI
Listening carefully to the speakers, try to determine the features of the organization of a particular class, and write down these features in a notebook
CLASS SCYPHOID
(disc 1 story) Not all coelenterates live at the bottom; many of them are able to swim in the water column. These include jellyfish. Scyphoid jellyfish are represented by species that live only in the seas. They are much larger than hydromedusas. These amazing creatures inhabit the sea from the surface to great depths. The body of the jellyfish is gelatinous, very different from polyps - it resembles a transparent dome or bell or umbrella in shape. Their sizes are different: cyanea, for example, it can reach 2 m in diameter, and the length of the tentacles is 30 m. The bell can contract; at the same time, water is forcefully pushed out from under it (not from the mouth!), and the animal moves in the opposite direction. This method of movement is called reactive.
Having opened up and spread the fringe of numerous tentacles, the jellyfish silently and smoothly sway in the calm water. But this serenity is deceptive. Graceful and delicate in appearance, in fact they, like all coelenterates, are predators. The long, thin tentacles of the jellyfish are covered with stinging cells and burn like fire. They kill prey with stinging cells. Each cell is a bag of poison, inside of which a rigid thread with a pointed end is coiled into a spiral; as soon as you touch the sensitive process on the edge of the capsule, the thread unwinds with lightning speed and pierces the prey with force. Hundreds of thousands of poisonous harpoons dig into the body of the victim, depriving him of the ability to move. The jellyfish immediately sends its prey into its mouth, which is located (disk ) in the center of the inner - concave - side of the body. Through it, undigested food remains are removed (as in hydroids). Surrounded by tentacles, the mouth opens into the digestive cavity. The body is formed by two layers of cells - ecto- and endoderm. Between them there is a gelatinous layer of mesoglea containing up to 98% water. The nervous system of scyphoids is more complex than that of other coelenterates. Along the edge of the umbrella there are groups of light-sensitive eyes and modified tentacles, acting as organs of balance.
Nervous system of diffuse type.
Video footage (movement of jellyfish).
Dangerous jellyfish.
Reproduction of jellyfish: (video)
Jellyfish are dioecious. The gonads are formed from the endoderm in the lower part of the stomach. Fertilization is external, development with metamorphosis. The life cycle occurs with alternating generations. The sex cells are expelled through the mouth. Fertilization and development occur in water. The larva emerges from the egg - planula, attached to the substrate. In the process of further development, a polyp is formed from it, the budding of which leads to the appearance of young jellyfish. Thus, scyphoid jellyfish have a clearly defined alternation of sexual and asexual generations, with the most developed sexual stage.
Scyphoid diversity.
? BeforeXVIII V. scientists had no doubt that these organisms were sea plants, microscopic “flowers” that immediately wither in the air. What are they called now?
Highest value in nature and for humans they have coral polyps. In the biocenoses of tropical seas they play an environment-forming role, forming the basis of reefs, atolls, and islands.
Class Coral polyps:
Coral polyps are the most extensive class of marine coelenterates, it has about 6 thousand species. Exclusively marine colonial, less often solitary forms, represented only by polyps. These are animals that lead an exclusively attached lifestyle. Sea anemones live separately from each other. Most types of corals are colonial forms, for example eight-rayed red corals, from which jewelry is made. Other, madrepore corals, growing, forming reefs in warm seas and oceans.
By internal organization coral polyps resemble hydroids. The body has the shape of a cylinder, at one end of which there is a slit-like mouth opening, surrounded by a corolla of tentacles; their number is eight (in eight-rayed corals) or a multiple of six ( six-rayed corals). The mouth leads into the throat. The other end of the polyp is attached to the ground or, in colonial forms, connected to other members of the colony through the digestive cavity.
The outer ectoderm folds over and lines the pharynx. The digestive cavity, lined with endodermal epithelium, is divided into chambers by partitions.
The vast majority of corals have a well-developed calcareous skeleton, external or located in the mesoglea. In some cases, in some species eight-rayed corals the skeleton is represented by a horn-like substance. There are coral polyps that lack a skeleton, such as sea anemone- a large single polyp, very reminiscent of a hydra and moving on a muscular sole.
When a single polyp settles on a stone or rock, it secretes a sticky substance and appears, as it were, inside a tube. It quickly hardens and becomes his family, a safe home. Soon a bud swells on the surface of the polyp's body: it grows, then bursts. This is how a mouth appears, tentacles appear around it - a new polyp is born. The sprouted crumb acquires its own limestone home, then buds again. And so many times until, over time, a colony is formed. In it, each polyp sits in its own calcareous cell, as if in a separate apartment, but does not live as a hermit, but maintains contact with its neighbors through thin channels. According to them, the caught and digested prey is fairly distributed among all members of the colony. In place of dead polyps, new ones settle using a lime flat former owner as a foundation for building your own home. This is how corals grow from generation to generation, centimeter by centimeter.
Corals live in warm, shallow sea waters. While they look like fancy plants, corals are actually made up of thousands of tiny sea animals. Places where there are large concentrations of corals are called coral reefs. Coral reefs form one of the most important ecosystems in the world's oceans. Their main feature is their unusually high productivity. The autotrophic photosynthetic production of the reef ecosystem ranges from 50 to 300 g of wet biomass per 1 m2 per day, and, unlike other highly productive ocean communities, it remains constant throughout the year. Fish resources reefs account for about 9% of the world's total stocks, and fisheries in this area have important as a source of food for the population of coastal tropical countries. Reefs are also a spawning and maturation site for many fish. The basis of the reef ecosystem is formed by organisms that intensively deposit lime: coral polyps, foraminifera, calcareous algae.
The total area of modern reefs is about 600 thousand km 2 .
The main reef massifs are located in the seas South-East Asia(45% of the world's reef area).
About 14% comes from the Atlantic,
17% - on Indian Ocean,
18% - on Pacific Ocean And
6% - to the Red Sea.
The largest reefs are the Great Barrier Reef of Australia, the barrier reef systems of Belize in the Western Atlantic, Tulear near the island of Madagascar, as well as reefs off the islands of Fiji and New Caledonia. The length of some of these reefs exceeds 1000 km. Most important representatives The fauna of coral reefs is undoubtedly the corals themselves. Without them, there would simply be no reefs. Another extremely important component of the coral reef community is plankton , since the reef benthic fauna is dominated by filter-feeding animals that feed exclusively on it. Species composition reef plankton and the sizes of its representatives are very diverse, ranging from bacterioplankton, represented by microscopic primitive prokaryotes, to ichthyoplankton, consisting of the larvae of vertebrate animals - fish. The phytoplankton of coral reefs is widely represented by unicellular algae. Zooplankton, in addition to fish larvae, includes various crustaceans, bristle-jawed , polychaetes, larvae of mollusks, echinoderms and coelenterates, as well as other small animals. Widely represented animal world the following main components: protozoa, coelenterates, worms, mollusks, sponges, bryozoans, crustaceans, echinoderms, tunicates, that is, representatives of almost all major types of the animal world. Coral fish deserve special mention. It is safe to say that the coral reef ecosystem is characterized by species diversity fish, unparalleled. Of approximately 20 thousand species bony fish 6-8 thousand living on our planet, their lives are associated with coral reefs. Moreover, if the total number of families of bony fish (including freshwater) is about 400, then the reefs are inhabited by representatives of more than 100 of them. The population density of coral fish is amazing, reaching 2 tons per hectare. From 60 to 70% of the reef ichthyofauna is represented by predators. The number of truly reef, highly specialized fish is noticeably smaller; the most widespread of them are representatives of approximately 500 species. Among them are bristletooth fishes - about 100 species, parrotfishes - about 80 species, pomacentral fishes - about 70 species, wrasse fishes - about 60 species, surgeonfishes - more than 40 species, apogonidae - about 30 species, gobies - about 30 species, rock perches - about 30 species, moray eels - about 20 species, scorpionfish - more than 15 species.
GREAT BARRIER REEF: a range of coral reefs and islands stretching for 2,300 km along the northeast coast of Australia. In the northern part the width is about 2 km, in the southern part - 150 km. Most of is under water. Marine National Park. (slide show)
Atoll- a coral structure in the form of a continuous or broken ring, remaining after a volcanic island sank into the ocean. In other words, they are low, ring-shaped islands that rise above sea level. Inside the ring there is a shallow body of water - a lagoon, with a quiet, clean water. Narrow channels can connect the lagoon to deeper open waters, but because the ring of land is almost closed, strong currents and powerful surf never reach the lagoon. Shallower marginal reefs act as stairs, connecting the shore to the deep ocean floor. The larger reefs on the outside are barrier reefs. They were once marginal reefs, but the bottom has sunk lower into the ocean, pushing them further from land. Coral structures are formed as a result of the vital activity of coral polyps and consist mainly of calcareous coral skeletons.
The largest atoll is Kwajalein, Marshall Islands, which includes a lagoon measuring 2,174 km.
Issues for discussion.
Answer the questions.
What progressive changes have occurred in intestinal polos?natural during evolution?
What does progressive change mean?
What does relative fitness mean?
What is symbiosis?
Is it dangerous to interact with coelenterate animals?
III. Consolidation of knowledge:
Test: (with the choice of one correct answer).
1. Among the groups of animals listed below, find the one inwhich includes only coelenterates.
A. Common amoeba, slipper ciliate, aurelia jellyfish.
B. Freshwater hydra, cornet jellyfish, red coral.
B. Dysenteric amoeba, rayweed, foraminifera.
G. Giardia, green euglena, suvoika.
2. In which animal has the cell lost its independence?and represents component whole organism?
A. In freshwater hydra.
B. In green euglena.
B. In an ordinary amoeba.
D. In foraminifera.
3.
Cells in the body of coelenterates
A. are located randomly;
B. form one layer;
V. form two layers;
G. are located in three layers.
4.
According to the method of feeding, coelenterates are:
A. predators;
B. herbivorous organisms;
D. autotrophic organisms.
5.
Freshwater hydra has body symmetry:
A. radial;
B. bilateral;
V. in the early stages of development is radial, and in adulthood - bilateral;
G. in the early stages of development is bilateral, and in adulthood - radial.
6. Hydra lives:
A. in rivers with fast current;
B. in ponds or rivers with slow flow;
V. at the bottom of seas and oceans;
G. in the thickness of sea water.
7.
Body length of freshwater hydra:
A. 1 mm;
8.
Hydra can swallow daphnia because:
A. it is larger than daphnia;
B. her body can stretch greatly;
B. she swallows prey gradually;
D. she has long tentacles.
9. What coelenterate moves by sharply pushing water out from under the bell?
A. Freshwater hydra.
B. Sea anemone.
B. Cornermouth jellyfish.
G. Red coral.
10.
Slowly relaxing and contracting the sole, he moves:
A. freshwater hydra;
B. aurelia jellyfish;
B. red coral;
G. sea anemone.
11.
When breathing, coelenterates absorb:
A. oxygen dissolved in water;
B. air oxygen;
B. air carbon dioxide;
D. carbon dioxide dissolved in water.
12.
The cover of the hydra's body is created by cells:
A. dermatomuscular;
B. stinging;
V. nervous;
G. intermediate.
13. The stretching and contraction of the hydra's body occurs due to:
A. change in length nerve cells;
B. straightening the stinging thread of stinging cells;
B. contraction and relaxation of muscle fibers of skin-muscle cells;
D. formation of pseudopods by digestive muscle cells.
Stinging cells are located mainly:
A. on the sole;
B. in the intestinal cavity;
B. in the inner layer of cells;
G. on the tentacles.
Hydra paralyzes prey and enemies using cells:
A. intermediate;
B. stinging;
V. nervous;
G. dermatomuscular.
Which cells are stellate in shape?
A. glandular;
B. stinging;
V. digestive-muscular;
G. nervous.
Excitation occurs in cells:
A. digestive-muscular;
B. stinging;
V. nervous;
G. intermediate.
18. Free-swimming marine coelenterates include:
A. freshwater hydra;
B. jellyfish;
V. sea anemone, brainwort;
(mutual checking, grading).
IV . Homework. study the text of the textbook; answer questions; outline the habitats of coral polyps and the Great Barrier Reef (creative assignment).
Didactic material to the lesson.
Complete the tasks in test form:(Using a computer).
1. Coelenterates:
a) lead an exclusively aquatic lifestyle;
b) live in water and soil;
c) live in ground-air environment.
2. Coelenterates:
a) bilayer animals;
b) three-layer animals;
c) there are two-layer and three-layer.
3. In the body of coelenterates one can distinguish:
a) ectoderm and endoderm;
b) ectoderm;
c) ectoderm, endoderm and mesoglea.
4. Nervous system:
a) absent;
b) diffuse;
c) nerve chain.
5. Stinging cells perform the following functions:
a) protection;
b) attacks;
c) defense and attack.
6. According to the method of feeding, coelenterates:
b) predators;
c) herbivores.
7. Reproduce:
a) asexually;
b) sexually;
c) asexually or sexually, depending on the conditions.
8. The digestive cavity has:
a) all coelenterates;
b) only hydras;
c) only coral polyps.
9. From intermediate cells the following are formed:
a) only germ cells;
b) only nervous ones;
c) all other cell types.
Compose an answer from several elements.
All coelenterates have radial body symmetry. In this regard, they are characterized following signs:
A. Only one plane of symmetry can be mentally drawn through their body.
B. Several planes of symmetry can be mentally drawn through their body.
B. Their organs, as a rule, are located in pairs.
D. Almost all species move actively.
D. The majority are sedentary or lead a sedentary lifestyle.
E. They catch prey or sense the appearance of danger from any side of their appearance.
Write down the letters indicating the names of coelenterate animals.
A. Common amoeba.
B. Green euglena.
B. Cornermouth jellyfish.
G. Red coral.
D. Volvox.
E. Freshwater hydra.
Write down the letters that code the characteristics characteristic of coral polyps.
A. Solitary organisms.
B. Colonial organisms.
B. They swim in the water column of seas and oceans.
D. They lead an attached lifestyle.
D. The mouth and tentacles are on the underside of the body.
E. They have a calcareous skeleton.
Coelenterates are multicellular animals with ray (radial) symmetry. Their body consists of two layers of cells and has a sac-like, so-called intestinal cavity. Coelenterates are characterized by the presence of special stinging cells.
Radiation symmetry is a characteristic common feature sessile or sedentary animals. In this case, the animal can be equally in danger from any side, and food also comes from all sides. Therefore, the bodies of these animals are designed in such a way that the means of protection or catching prey are directed in different directions, like rays (or radii) from a single center.
Coelenterates are the most ancient and primitive multicellular animals. They evolved from primitive primordial multicellular organisms.
All coelenterates are aquatic animals, most of which live in the seas and oceans. They inhabit seas from the surface to extreme depths, from tropical waters to polar regions. A small number of species live in fresh waters. About 9,000 species of coelenterates are now known. Among them there are solitary and colonial animals.
A group of individuals that have similar adaptations for living in the same environment is called a life form of animals. Modern coelenterates are characterized by two life forms (two generations): an attached form - a polyp and a free-swimming form - a jellyfish.
Polyps (from the Greek polyp - “multipede”) - a life form, so named for its numerous tentacles. In rare cases (Fig. 36, A) polyps are single (for example, hydra and sea anemone), but more often they form colonies of up to several thousand individuals. In the form of a jellyfish (Fig. 36, B), coelenterates, as a rule, live solitarily.
Rice. 36. Schemes of the structure of coelenterates: A - polyp; B - jellyfish
In many coelenterates, both life forms (both generations) replace each other (alternate) during life cycle- from the birth of an organism to death. Some (hydra, coral polyps) do not have a free-swimming form - jellyfish. Others (some scyphoid jellyfish; see next paragraph) have lost their polyp form.
The body of coelenterates resembles a two-layer sac open at one end. The outer layer of cells is called ectoderm (from the Greek ectos - “outside” and dermis - “skin”), and the inner layer is called endoderm (from the Greek entos - “inside” and dermis - “skin”). The only body cavity of these animals, the intestinal cavity, communicates with the external environment through the oral opening (mouth). Through the mouth, food enters the intestinal cavity, and undigested residues are expelled through it.
In coelenterates, stinging cells are located on the tentacles. They serve both for catching prey and for defense. Coelenterates are predators. They feed on various small animals that “float” in the water column.
Coelenterates reproduce both asexually and sexually.
The importance of coelenterates
Coelenterates have great importance in nature. Many fish feed on coral polyps and hide among the limestone, branched “forests” built by these animals. sea turtles and some fish eat jellyfish. The coelenterates themselves, being predators, influence marine animal communities by eating planktonic organisms, and large sea anemones and jellyfish also eat small fish. Humans use some coelenterates. From the dead calcareous parts of coral reefs in some coastal countries they extract construction material, when roasted, lime is obtained. Some types of jellyfish are edible. Black and red corals are used to make jewelry.
Some swimming jellyfish, sea anemones and corals with stinging cells can cause severe burns to fishermen, divers and swimmers. Coral reefs impede shipping in some areas.
Freshwater hydra - single polyp
Habitat. External structure. Lifestyle. Movement. Freshwater hydra lives in areas with clean water (in river backwaters, lakes and ponds) (Fig. 37). This is a small translucent animal about 1 cm long. The body of the hydra has a cylindrical shape. With its lower end (sole) it is attached to the stems and leaves aquatic plants, snags and stones. At the upper end of the body, around the mouth, there are 6-12 tentacles. Hydra, like other coelenterates, is characterized by radial symmetry. Hydra leads sedentary lifestyle life. Its body and tentacles can lengthen and shorten. IN calm state the tentacles extend several centimeters. The animal slowly moves them from side to side, lying in wait for prey. If necessary, the hydra can move slowly. At the same time, it seems to be walking (tumbling), attaching itself to underwater objects alternately with the upper and lower ends of the body.
Rice. 37. Scheme of the structure of freshwater hydra: 1 - ectoderm; 2 - endoderm; 3 - mesoglea: 4 - sole; 5 - intestinal cavity; 6 - kidney; 7 - tentacle; 8 - mouth
The hydra's body looks like an oblong sac, the walls of which consist of two layers of cells - ectoderm and endoderm. Between them lies a thin gelatinous non-cellular layer - mesoglea, which serves as a support. The intestinal cavity of the hydra communicates with the external environment only through the mouth.
The ectoderm forms the covering of the animal’s body and consists of several types of cells (Fig. 38). The most numerous of them are epithelial-muscular. Due to the muscle fibers lying at the base of each cell, the hydra's body can contract, lengthen and bend.
Rice. 38. Section through the body of the hydra - ectoderm cells (1-4) and endoderm (5, 6): 1 - epithelial-muscle cells; 2 - intermediate cell; 3 - stinging cell; 4 - nerve cell; 5 - digestive-muscle cell; 6 - glandular cell; 7 - mesoglea
The ectoderm contains star-shaped nerve cells. The processes of neighboring nerve cells connect with each other, forming a nerve network that covers the entire body of the animal and represents the most primitive nervous system in animals.
If you touch the hydra or prick it with a needle, the animal will shrink. This happens because the signal received by even one cell will spread throughout the entire nerve network. Nerve cells “give command” to epithelial muscle cells. The muscle fibers contract, and then the entire body of the hydra shortens (Fig. 39). The response of the hydra body to such irritation is an example of an unconditioned reflex. Unconditioned reflexes characteristic of all multicellular animals.
Rice. 39. Stimulation of hydra nerve cells
The ectoderm also contains stinging cells that serve for attack and defense. They are mainly located on the tentacles of the hydra. Each stinging cell contains an oval capsule in which the stinging filament is coiled. If prey or an enemy touches the sensitive hair, which is located outside the stinging cell, in response to irritation the stinging thread is ejected and pierces the body of the victim (Fig. 40). Through the thread channel, a substance that can paralyze it enters the victim’s body.
Rice. 40. Diagram of the structure of a stinging cell: 1 - nucleus; 2 - stinging capsule; 3 - sensitive hair; 4 - stinging thread: coiled (left) and thrown out (right)
There are several types of stinging cells. The threads of some pierce the skin of animals and introduce poison into their bodies. The threads of others are wrapped around the prey. The threads of the third are very sticky and stick to the victim. Usually the hydra “shoots” several stinging cells.
The ectoderm also contains intermediate cells. From them other types of cells are formed.
Endoderm lines the entire intestinal cavity from the inside. The endoderm consists of digestive muscle and glandular cells. There are more digestive muscle cells than others. Their muscle fibers are capable of contraction. When they shorten, the hydra's body becomes thinner. Complex movements, for example the hydra's "tumbling" movement, occur due to contractions of the muscle fibers of the ectoderm and endoderm cells.
Nutrition. Each of the digestive-muscle cells of the endoderm has one to three flagella. Vibrating flagella create a current of water, which drives food particles towards the cells. The glandular cells present in the endoderm secrete digestive juice into the intestinal cavity, which liquefies and partially digests food.
Digestive muscle cells of the endoderm are capable of forming pseudopods, capturing and digesting small food particles in the digestive vacuoles. Thus, digestion in hydra and all coelenterates is intracellular and cavity.
Nutrients are distributed throughout the hydra's body. Undigested residues are removed through the mouth. Hydras feed on small invertebrate animals (often crustaceans - daphnia and cyclops), which they catch with their tentacles.
Breathing and excretion. Hydra breathes oxygen dissolved in water. She has no respiratory organs, and she absorbs oxygen over the entire surface of her body, releasing carbon dioxide outward. In the process of life activity, cells form harmful substances that are released into the water.
Reproduction and development. Hydra reproduces sexually and asexually. Asexual reproduction carried out by budding (Fig. 41). A protrusion forms on the body of the hydra - a kidney. It consists of two layers of cells - ectoderm and endoderm - and communicates through a common cavity with the maternal body. The kidney enlarges and grows in length. A mouth and small tentacles appear at its top, and a sole appears at the base. After this, the young hydra separates from the mother’s body, sinks to the bottom and begins an independent lifestyle. Often several buds form on the hydra’s body at once. Hydras most often reproduce asexually.
Rice. 41. Asexual reproduction of hydra (budding)
In autumn, with the approach of cold weather, hydras begin to reproduce sexually (Fig. 42). Sex cells are formed in the ectoderm from intermediate cells. Two types of tubercles appear on the body of the hydra. In some, sperm are formed, in others, eggs.
Rice. 42. Sexual reproduction hydra
There are hydras in which sperm and eggs are formed on different individuals. These are dioecious animals. In other species of hydras, both sperm and eggs are formed on the body of one organism. Such animals, combining the characteristics of both female and male genders, are called hermaphrodites.
Once in the water, the sperm swims with the help of a long flagellum and reaches the immobile eggs. Fertilization (the union of a sperm with an egg) occurs in the body of the mother's body. After this, a dense membrane is formed around the fertilized egg. A fertilized egg divides multiple times to form an embryo. In the fall, the hydra dies, and the shell-covered embryos sink to the bottom. In spring, embryo development continues. After the reservoir warms up, the membranes covering the embryos are destroyed and small hydras come out.
Regeneration. A damaged hydra easily restores lost body parts (Fig. 43) not only after it has been cut in half, but even if it has been dismembered into many parts. From each part a new small hydra is formed. This occurs due to the intensive division of intermediate cells, from which other types of cells arise. The ability of animals to restore damaged or lost body parts is called regeneration.
Rice. 43. Hydra regeneration
Hydra is a multicellular animal with a primitive structure. Her intestinal cavity looks like a solid bag. The nervous system consists of scattered stellate nerve cells that form the nerve network. Asexual reproduction occurs by budding. Hydra also reproduces sexually.
Exercises based on the material covered
- List the main structural features of representatives of the phylum Coelenterata.
- What is the significance Various types Hydra's cells?
- Describe radial symmetry using the example of one of the representatives of the coelenterate phylum.
- What kind of life do coelenterates lead?
- How does a hydra move?
- Describe the vital functions of coelenterates: nutrition, digestion, reproduction (using the example of hydra).
- Explain, using a picture, the regeneration process of the hydra.
- What is the significance of coelenterates?
· Environment-formers of biocenoses of coral reefs and atolls.
· Formers of calcareous rocks.
· They gave rise to the first three-layered animals.
· They are a link in the food chain of aquatic biocenoses,
· Some are eaten by humans (aurelium and rapilleme) and used as decoration.
· Some are poisonous and dangerous to humans and animals (jellyfish cross, cornet, etc.).
· Coelenterates are the most ancient of the true multicellular animals. Over the long history of the development of this type, its representatives have managed to adapt very well to a wide variety of living conditions. They populated literally the entire ocean from its surface to the extreme depths; they can also be found in polar regions and in the tropics.
· Coelenterates settle on a wide variety of soils, some of them are able to withstand significant changes in the salinity of sea water, and individual species even penetrated fresh waters. Almost everywhere they play a very important role in the formation of communities of marine animals and plants - sea biocenoses.
· Biological significance Coelenterates are large in the food chains of the World Ocean. They are especially important in absorbing suspended organic matter and purifying sea water. The role of coral polyps in the calcium cycle in the biosphere and the formation of sedimentary rocks is great.
· Coelenterates are commercial objects. Salted jellyfish are used as food. Their fishery is of local importance, mainly in Japan and China. The main commercial interest is from corals, from which jewelry and art objects are made. In addition, collecting coral polyps is now popular. Coral branches are sold as souvenirs. Red and black corals are especially prized. Jewelry is made from them. Coral limestones are an excellent building material. In addition, lime is obtained from them. Some hydroid polyps are extracted to obtain biologically active substances for medicine.
Coral polyps take part in the formation of relief earth's surface. Other animals (echinoderms, mollusks, worms, fish - biofile.ru) settle in their “thickets” or on their surface. The skeleton of corals forms deposits of lime. Reefs make it difficult for ships to pass. Various types of jellyfish, which are poisonous animals (cross, Portuguese man of war), may pose a danger to humans. The poison is the products of the activity of stinging cells. In China, some scyphoid jellyfish are hunted as food.
10.Type Flatworms (structure and activity) p.68
TYPE FLATWORMS
CLASS PLANARIA, OR CILIA WORMS
Habitats, structure and lifestyle.
White, brown, and black planaria live in silted areas of lakes, ponds and streams. At the front end of their body two ocelli are noticeable (they distinguish light from darkness); The pharynx is located on the ventral side. Planarians are predators. They attack small aquatic animals, “crush” them under themselves and swallow them whole or tear them into pieces. They move thanks to the coordinated work of the cilia. The body length of freshwater planarians is 1-3 cm.
The world of marine ciliated worms is the richest and most diverse. Their large, wide leaf-shaped body has a wide variety of colors. In damp litter tropical forests live large soil planarians (bipalians), whose body length reaches 60 cm.
Internal structure and vital activity. The body of flatworms is covered with elongated cells with cilia. There are three layers deeper muscle fibers(circular, diagonal and longitudinal). Thanks to their contraction and relaxation, the worm lengthens or shortens, lifts one or another part of the body, and flattens. Under the muscles there is a mass of small cells - the main tissue, and in it - the internal organs. The digestive system consists of a mouth with a muscular pharynx and a three-branched intestine, the walls of which are formed by a single layer of flask-shaped cells capable of capturing food particles and digesting them. The glandular cells of the wall secrete digestive substances into the intestinal cavity. The resulting nutrients penetrate all cells of the body, and undigested food remains are removed through the mouth.
Ciliated worms breathe oxygen dissolved in water through the entire surface of the body. Substances that are unnecessary for the body, formed during the process of vital activity, are eliminated by entering the tubules, which begin with large stellate cells with bundles of cilia inside (they create a flow of fluid into the tubules). Small tubules are collected into one or two large tubules with excretory pores.
The nervous system of ciliated worms is formed by clusters of nerve cells - paired head nodes, nerve trunks and nerve branches extending from them. Most ciliated worms have eyes (from one pair to several dozen), tactile cells in the skin, and some have small paired tentacles at the anterior end of the body.
Reproduction of eyelash worms. Flatworms are usually hermaphrodites. Freshwater ciliated worms, such as planarians, lay fertilized eggs in cocoons formed from solidified mucus. The developed small worms break the walls of the cocoons and come out. In marine eyelash worms, fertilized eggs hatch into floating larvae, which then acquire the characteristics of adults.
CLASS FLUKES AND CLASS TAPEWORMS
Muscular and nervous system in tapeworms they are poorly developed, and the sensory organs are represented by sensitive skin cells. Their digestive system has disappeared: they absorb nutrients throughout the entire surface of the body from the host’s intestines.
The greatest development in tapeworms is reproductive system. Almost all of them are hermaphrodites. Their last segments seem to be filled with eggs with developing embryos. The segments are separated from the body of the worm and come out with the feces of the owner or independently (due to muscle contraction). A sick person hatches up to 28 segments per day, containing up to 5 million eggs. Together with the grass, the eggs enter the stomach of the intermediate host - a cow (bovine tapeworm), a pig (pork tapeworm). In the stomach, six-hooked larvae emerge from the eggs, which penetrate the blood vessels of the intestine and then into the muscles. Here the larvae turn into fins, which look like a bubble the size of a pea. When a person eats undercooked or undercooked Finnish meat, he or she becomes the main host of the worm. In the human stomach, the head of the finna is turned out, and the bubble itself is digested. Little worm enters the intestine, sticks to its wall, and its neck begins to form segments.
The development of the wide tapeworm is associated with the change of two intermediate hosts (Cyclops crustaceans and fish). The main owner is a person.
Echinococcus- small worm (length up to 6 mm). Unlike tapeworms and tapeworms, the segments are not separated from its body. The main hosts of echinococcus are dogs, wolves, foxes, and cats; intermediate - sheep, cow, goat, deer, pig (maybe a person). In the liver, lungs, muscles, and bones of intermediate hosts, large blisters (a variety of Finns) develop, in each of which daughter and grandchild blisters with heads inside develop. The primary hosts become infected by eating meat with echinococcal blisters, and intermediate hosts by eating food contaminated with the feces of sick dogs, wolves and other primary hosts of echinococcus.
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