Lesson topic: The world ocean is the cradle of life.
Lesson type: lesson - travel.
The purpose of the lesson: to generalize and systematize knowledge from the field of biology of physics, to establish interdisciplinary connections; show the connection between theory and practice; show the importance of the World Ocean and the main problems associated with its study and development.
Equipment e: presentation "World Ocean", tables, geographic map, video footage.
DURING THE CLASSES.
Statement of the educational problem.
Greetings to all those present on board the Krym cruise liner: dear friends, today we will make an unforgettable journey across the World Ocean, we will descend into its depths on a bathyscaphe and get to know its inhabitants. Today we will be accompanied by experts who will provide us with the necessary assistance when we need it.
Generalization and systematization of knowledge.
The first word is given to an expert geographer, who introduces the basic data on the World Ocean: surface area, average depth, salinity, mineral deposits, biosphere.
A video film is shown, which shows the inhabitants of the underwater kingdom, deep-sea vehicles - bathyscaphe, bathysphere, scuba divers studying the underwater world.
During the demonstration of the video, we make pauses, during which short messages from students are heard and what they see is discussed. From the physical point of view, the following questions are proposed.
● Why is special equipment needed to explore underwater depths?
● How does the oxygen needed for fish to breathe get into the water?
● Why do fish need a swim bladder?
● How is the diving depth of fish regulated with it?
● Why are the stems of underwater plants soft and flexible?
● How to measure the depth of water under a ship?
● Why are fish, sharks, dolphins streamlined?
● Why is oil pollution of water dangerous?
Expert biologists characterize the animals that students see on the screen.
◄ Expert - biologist.
More than 160 thousand species of animals and about 10 thousand species of algae live in the world's oceans. Algae play a significant role in providing oxygen to the inhabitants of the waters, a person consumes them for food, uses them as fertilizers, they produce iodine, alcohol, acetic acid. 85 million tons of fish are caught annually in the World Ocean. This is not only 1% of world food production, but also 15% of animal proteins consumed by mankind. The ocean shelf contains the greatest reserves of oil and gas, iron-magnesium ores and other minerals.
◄Oceanologist
Sharks - from a number of lamellar-gill fish. Body length from 0.2 m (black shark) to 20 m (giant shark). About 250 species are known. Widespread mainly in tropical seas. Object of fishing (meat is eaten, fish oil is obtained from the liver, glue is obtained from the skeleton) Large sharks (Whale, blue) are dangerous to humans.
◄Physiologist
An electric ramp can create a voltage of 650 V. An interesting recipe for electrotherapy with an electric ramp was described by an ancient Roman healer in the 1st century AD: “ Headache disappears if a live black stingray is placed on a painful point and held until the pain disappears. The ancient Greeks believed that electric stingrays could "bewitch" the victim, and called them "narke" - i.e. one that causes numbness, hence the name "drug".
The span of manta fins reaches 8 m. Weight is about 3 tons. He has small horns on his head, with which he drives small fish into his mouth. For these "horns" they were nicknamed "sea devils"
◄ Geneticist
The moray eel has a snake-like body 3 m long. There are sharp teeth on the jaws, which were previously mistakenly considered poisoned. Skin without scales. Moray eels usually hide in the crevices of underwater reefs and rocks, waiting for their prey - fish, crabs, cuttlefish. The moray eel itself does not attack a person, only if it is disturbed. The meat of some species of moray eel causes severe poisoning if it is eaten.
◄ Biophysicist
The specific gravity of cartilaginous fish is greater than the specific gravity of water, so they must constantly move their tail so as not to fall to the bottom. In addition, underwater currents help them move in the water.
Every year 5-10 million tons of oil enters the World Ocean. To understand how much this is, we can give the following example: 1 liter of spilled oil blocks the access of oxygen to 40 thousand liters sea water. We know that the density of oil is less than the density of water, so it spreads over the surface of the water and creates a thin film on its surface. According to American scientists, 1/3 of the ocean is covered with oil. Not only that, without access to oxygen, fish that breathe it can die, but this is a real misfortune for waterfowl. How do you figure out why?
◄Microbiologist
The oil slick does not let the sun's rays through, as a result of which plankton, the basis of food for marine life, ceases to multiply. Liquid and solid household waste (feces, synthetic films and containers, plastic nets) enter the seas and oceans. These materials are lighter than water, and therefore float on the surface for a long time. In fish that have survived in such conditions, mollusks and crustaceans have a reduced growth rate. Often the species composition of organisms also changes.
Summing up the lesson
The teacher sums up the lesson, once again focuses on environmental issues of the oceans associated with human life. Thank you all for your hard work.
In the Proterozoic and the first half of the Paleozoic, that is, for 600 million years, life continued to develop mainly in water - in the oceans and seas, which were the cradle of life on our planet. Land plants and animals began to develop much later.
We know that at present organic world oceans and seas is great and varied. Many primitive and ancient organisms live there.
More than 150 thousand species of animals and about 10 thousand species of algae live in the oceans and seas.
In the first place are molluscs, there are more than 60 thousand species, crustaceans - about 20 thousand, marine fish - more than 16 thousand species, unicellular - about 10 thousand, worms and animals close to them - more than 7 thousand species, coelenterates - about 9 thousand, echinoderms - 5 thousand, sponges - 4 thousand species.
There are many more animals that live in water than on land. From total number There are 63 classes of animals and 33 classes of plants that currently exist, 37 classes of animals and 5 classes of plants live in the sea alone.
The world of living beings of the seas and oceans has gone through a grandiose path of historical development.
During this huge period of time that we are talking about, many great events have taken place in the development of life on Earth. Here are the main ones.
The first event is the appearance of multicellular organisms, the second is the emergence and flourishing of various algae and marine invertebrates, and the third is the appearance of the first vertebrates.
The greatest leap in the development of life was the emergence of multicellular organisms, for this provided enormous opportunities for its further progressive development.
It probably happened in the following way. Each unicellular organism is a small but extremely complex apparatus capable of carrying out all vital functions: nutrition, excretion, respiration, movement, reproduction. Multicellular organisms are different. In them, each cell or group of cells is adapted to perform a specific function. In simple multicellular organisms, for example, in some flagellar algae from the Volvox group, there has not yet been such a division of functions between cells. Volvoxes - spherical organisms - consist of a single layer of cells on top, and are filled with liquid inside. They are, as it were, colonies of unicellular creatures, the ancestors of multicellular ones. Subsequently, the cells of such organisms specialized: some cells began to perform, for example, a motor function, others - a nutritional function, others - a reproductive function, etc. This is how multicellular organisms with various organs arose. The most substantiated theory of the origin of multicellular animals is the theory put forward by II Mechnikov. According to I. I. Mechnikov, the initial form for multicellular organisms was parenchymella, similar to the larva of sponges - parenchymula and the larva of coelenterates - planula. Parenchymella could have arisen from colonies of flagellates, similar to Volvox. Later, the protective cells of the outer layer (ectoderm) arose in the ancestors of multicellular organisms, and the inner cells began to carry out the digestive function and turned into the intestinal cavity (endoderm).
The change and development of ancient multicellular organisms took place in different ways under different environmental conditions. Some of them became inactive, settled to the bottom and attached to it, others retained a mobile lifestyle. A variety of multicellular organisms arose: algae, as well as sponges, jellyfish and other invertebrate animals that inhabited ancient seas and oceans. The appearance of these organisms dates back to a very remote time, but, despite this, they have changed very little since then and have not given rise to other animals.
The ability for progressive development was shown by completely different ancient multicellular animals, relatives of jellyfish - ctenophores, which had sufficient mobility. At a certain stage of their development, they were forced to change their way of life: swimming to crawling. This entailed a change in the structure: flattening of the body, the formation of a head, the appearance of differences between the peritoneum and dorsal sides. Thus aquatic worms were born. Gradually, they developed greater mobility, muscle fibers formed, and circulatory and other organ systems appeared.
ancient primitive annelids gave rise to arthropods. Short non-segmented appendages, or parapodia, of the annulus turned into long articular legs capable of very complex movements, the brain and all nervous system in arthropods have increased and become more complex, and the sense organs, such as the eyes, have reached high degree development. Since the beginning of the Paleozoic, trilobites, crustaceans, and lower crustaceans have been known. Later, arachnids, centipedes, and insects arose. Paleontological, comparative anatomical and embryological data show that crustaceans originated from one group of annulus, trilobites, horseshoe crabs, arachnids from another, centipedes and insects from a third.
The ancestors of mollusks were probably close to the rings. This is indicated by the structural features of lower mollusks and the striking similarity of embryonic development (the structure of eggs and larvae, the similarity of developmental stages, etc.) between mollusks and annelids. But in mollusks, a non-segmented, concentrated type of structure arose. The main classes of mollusks appeared in the Precambrian and are well known from the Cambrian period. Mshanki, brachiopods, also known from the oldest deposits, come from some worm-like forms; have, on the other hand, proximity to the coelenterates. Brachiopods - marine animals - look like mollusks, but their shell does not open to the sides, like in bivalve mollusks, but from the bottom up. On the sides of the mouth they have two outgrowths called "hands". They are respiratory organs and create a current of water at the mouth. The brachiopods were a hydroid polyp - one of the simplest widespread animals in the ancient seas.
An extensive and peculiar type of echinoderms (starfish, hedgehogs, lilies, brittle stars or serpenttails) arose and developed rapidly long before the Cambrian from worm-like ancestors. Their probable ancestors were freely mobile, bilaterally symmetrical worm-like animals with three pairs of separated internal cavities, which did not have an internal and external skeleton.
All this happened over 500 million years ago.
Thus, life in the Archean and Proterozoic era was concentrated and developed in water. The seas and oceans were the cradle of life on our planet.
In the next - Paleozoic - era, which began about 500 million years ago and lasted more than 300 million years, living beings continued their further development. This era is divided into five periods: Cambrian, Silurian, Devonian, Carboniferous and Permian.
The first half of the Paleozoic - Cambrian and Silurian periods. It was a quiet time in the history of the Earth. The continents were then located lower than they are now, and, consequently, the oceans occupied a large surface and formed many deep seas.
In them, as in the Proterozoic era, algae lived, various invertebrates attached to the bottom crawled, swam or slightly moved. Sponges, archaeocyates and trilobites began to spread in large numbers. The word "archaeocyates" in translation into Russian means "ancient glasses". They were named so because these animals really looked like a glass or goblet. Many of their remains have been found on the territory of modern Siberia in the form of fossil reefs.
Archaeocyates were related to sponges and corals, had a strong calcareous skeleton and were attached to the bottom with long threads.
Trilobites, relatives of crustaceans, looked like wood lice in appearance and were apparently akin to modern horseshoe crabs and sea scorpions. Their body, consisting of a head, torso and tail, was covered with shields. Some trilobites were very small - the size of a pea, others reached half a meter in length. They swam or crawled in shallow bays, feeding on plants and the bodies of dead animals.
In those days, numerous and diverse sponges, corals, worms, brachiopods, mollusks, echinoderms (starfish, lilies, sea urchins). But the main inhabitants of the current seas and oceans - fish - have not yet been. Scientists have found the first rare fish imprints in late sediments of the Silurian period. This means that their age reaches 400 million years! What were the ancestors of fish?
For a long time, science did not find an answer to this question. Research only
the outstanding Russian embryologist Alexander Onufrievich Kovalevsky, as well as recent paleontological discoveries, shed light on the mystery of the origin of fish. It turns out that they originated from marine worm-like animals. Ancient fish had a narrow, long body. There were no bones inside the body, but outside it was sometimes covered with armor. The ancient fish did not have paired fins. They looked like living creatures today: lampreys and hagfish, and at the same time they looked like a small, 5-7 centimeters long, fish-like animal, simple in structure - the lancelet. He lives in the seas, in sandy soil, and is also found in our Black Sea. It is remarkably built, as it has the features of invertebrates and vertebrates. Its body is long, pointed downwards, similar to a lancet, consists of a number of segments, that is, it has an articulated structure, like in many worm-like invertebrates. On the other hand, it is related to vertebrates by the presence of a notochord, the brain, and a complex gill apparatus.
The internal structure and larval development of the lancelet, studied by A. O. Kovalevsky, speaks of a close relationship both with the lower chordates - tunicates and ascidians - and with vertebrates, in particular fish.
Most hallmark, which distinguishes chordate animals, which include the lancelet and a number of other animals close to it, as well as all vertebrates, is the presence of a chord - a dorsal cartilaginous string or spine, the location of the brain above the anterior part of the chord, the presence of a complex gill apparatus or lungs.
In the sediments of the Silurian and Devonian periods, extremely well-preserved remains of ancient fish have been found. From these remnants, one can even judge how the main blood vessels and nerves were located.
The most ancient vertebrates known to us are the jawless scutes. In appearance, they resemble fish, but they still cannot be called fish. They did not have jaws and paired fins, like lampreys and hagfishes. Their close relatives, the so-called armored fish, had jaws, paired fins, had a more advanced internal skeleton, brain and sensory organs. But their body was fettered by a massive bone armor that covered the head and anterior part of the torso. All these fish died out in the Devonian period, about 300 million years ago, giving way to cartilaginous and bony fish.
There are two points of view on the question of where the first vertebrates appeared - in the seas or fresh waters. In favor of marine origin speaks a significant amount of calcium dissolved in sea water, which is part of the bones, as well as the habitat of all lower vertebrates in the sea. Proponents of freshwater origin consider the cause of the appearance of the skeleton in general as a stable support of the body and believe that it must have arisen in running water, actively resisting the flow. There is no doubt that the ancestors of vertebrates lived in a zone where fresh water border on the sea, - there they find their remains. The oldest vertebrates known to us already possessed bone tissue - armor, - their internal skeleton was, apparently, cartilaginous; it has not been preserved in a fossil state. Replacement of cartilage by bone (ossification of cartilage) occurred much later - in higher groups of fish.
It should also be noted that the salinity of sea water was then lower than it is now, so fish could probably more easily move from sea water to fresh water and vice versa.
THE OCEAN IS THE CRADE OF LIFE
Life in the oceans originated over a thousand million years ago, but what mysterious forces forced living organisms to develop and multiply remains a mystery to this day.
Four main theories try to explain the origin of life on earth. The first asserts that the universe exists forever, and living cells have always existed in it. As soon as a red-hot star cools down to a temperature at which the existence of life is possible, it is populated tiny living particles "cosmozoans", which are carried by cosmic rays from other celestial bodies. This simple and peculiar hypothesis corresponds to the theory of the continuity of matter, which in recent times appeared in scientific world. The hypothesis is constructed so artificially that it can neither be refuted nor confirmed.
The second hypothesis is based on a mystical beginning, considering the origin of life on earth as a result of supernatural interventions. The hypothesis is primitive, but all the religions of the world are based on it, and even today many people endowed with great intelligence tend to this point of view. To accept this hypothesis means to throw humanity into the abyss of ignorance and superstition and completely deny the greatness of modern science.
The third hypothesis is that life started by accident as a result of interaction
chemical elements, which was facilitated by favorable conditions. When a sufficient variety of chemical elements accumulated, the number of their chaotic compounds increased significantly, one of which gave rise to living cells. Mathematics proves that if you continuously throw twenty dice, then after numerous attempts, twenty sixes or twenty ones can fall out at once. It can also be shown mathematically that chemical elements, continuously interacting with each other under conditions of a certain temperature and pressure, can form a living cell. Many supporters of this hypothesis believe that changes in nature occur by chance, just as the evolution of matter itself is random.
The fourth hypothesis states what Live nature appeared as a result of an inevitable and natural process: amphibians developed from vertebrates and invertebrates that lived in ancient seas, reptiles - from amphibians, mammals - from reptiles. There was no gap between animate and inanimate nature in a single evolution. One of the main stages of evolution - the development of a living being from an inanimate one - took place on the border between land and the primary ocean.
In nature, there are amazing organisms - filter viruses, which are located on the border between living and non-living matter. Some of these viruses, taken in isolation, are tiny solid bodies, but as soon as these viruses connect with living tissue, they immediately “come to life”. An example would be tobacco mosaic virus. In isolation, this virus is an inanimate substance, unable to reproduce, but introduced into the tobacco leaf tissue, it multiplies rapidly and infects the plant.
All modern hypotheses recognize the leading role of sea water in the origin and development of life. The ocean not only gave birth to life, but continues to support it with its life-giving moisture. The fluid contained in the body of all living organisms, from the simplest invertebrate to man, is similar in composition to sea water, and differs very little from it in the composition of salts, and in some animals (for example, in a dog) it completely coincides. This may serve as the main evidence that life arose in the ocean, which is the progenitor of all life.
But the ocean not only gave rise to life, it continues to support it in all biological forms. All terrestrial animals carefully store their moisture, protecting themselves with waterproof skin, and plants with their roots suck life-giving moisture from the earth. In extreme conditions, one of the main dangers to humans is often dehydration. The maximum survival without water at normal temperatures is no more than 14 days, at high temperatures in tropical latitudes this period is much less. In the absence of food, the survival limit reaches 60-70 days. Marine animals do not have to struggle to retain moisture while they are in their native element, but thrown ashore by the tide or storm, they become helpless and quickly die. Hence the famous saying: "Like a fish thrown out of the water".
Life in the ocean has its own characteristics: water salinity, illumination, high pressure, low oxygen content and low temperatures at great depths. marine organisms are able to live at a high concentration of salts, but salinity has a noticeable effect on the distribution of species. In relatively shallow places where the sun's rays penetrate in sufficient quantities, the fish are better illuminated from the back than from the sides, and therefore shallow water fish have an appropriate protective color - the dark color of the back gradually turns into a light color of the belly. The deeper the sun's rays penetrate into the water column, the weaker they become, darkness reigns at great depths, and deep sea animals acquired luminous organs, allowing them to navigate in the dark.
With increasing depth, the pressure increases and when diving to 1000 meters it reaches 100 atmospheres. Under such pressure, a piece of a wooden block or cork is halved in volume, and at a depth of 5000 meters, the phenomenon of “explosions” is observed, under the influence of which glass products enclosed in thick-walled metal boxes break into pieces. Deep-sea animals feel comfortable at any depth, since the pressure of the liquid of internal tissues is equal to the pressure of water, but if it is outside the deep environment, it will immediately be thrown to the surface and torn to pieces - the animal will die, "crashed when falling up".
The ocean contains a strictly limited amount of oxygen, which is only enough for chemical processes that ensure the growth of marine animals and their movement in search of food. Physical activity of any animal depends on the amount of oxygen, and since its concentration in the ocean environment is low, the pace of life in the oceans is slower than on land. Most of all oxygen is in the surface layer of the seas, which in the process of photosynthesis saturates microscopic plankton with oxygen. Marine life does not suffer from a lack of oxygen, since they spend much less energy on their movement, overcoming the forces gravity. The density of the bodies of marine animals and plants is very close to the density of ocean water, so the environment supports them - they can easily float up, sink to a depth, or just stop in thought, watching the world around them. This is how a good swimmer feels in the water.
At great depths reigns not only eternal darkness, but also eternal cold. Swimming in the tropics under the streams sunlight warming the upper layers of the ocean, it is hard to imagine that below, at a depth of 600 meters, the temperature is only 4 ° above the freezing point. In the high southern latitudes, the influence of eternal ice, and the bottom water temperature in Antarctica drops to 0.5°C. Thus, the deep animals live in an almost unchanged world, where eternal night reigns and eternal winter reigns.
The ocean is one of the great natural regions of the Earth, providing conditions for a variety of life forms.
Lesson type: lesson - travel.
The purpose of the lesson: to generalize and systematize knowledge from the field of biology of physics, to establish interdisciplinary connections; show the connection between theory and practice; show the importance of the World Ocean and the main problems associated with its study and development.
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Lesson topic : The world ocean is the cradle of life.
Lesson type : lesson - travel.
The purpose of the lesson: to generalize and systematize knowledge from the field of biology of physics, to establish interdisciplinary connections; show the connection between theory and practice; show the importance of the World Ocean and the main problems associated with its study and development.
Equipment e: presentation "World Ocean", tables, map, video.
DURING THE CLASSES.
- Statement of the educational problem.
Greetings to all those present on board the Krym cruise liner: dear friends, today we will make an unforgettable journey across the World Ocean, we will descend into its depths on a bathyscaphe and get to know its inhabitants. Today we will be accompanied by experts who will provide us with the necessary assistance when we need it.
- Generalization and systematization of knowledge.
The first word is given to an expert geographer, who introduces the basic data on the World Ocean: surface area, average depth, salinity, mineral deposits, biosphere.
A video film is shown, which shows the inhabitants of the underwater kingdom, deep-sea vehicles - bathyscaphe, bathysphere, scuba divers studying the underwater world.
During the demonstration of the video, we make pauses, during which short messages from students are heard and what they see is discussed. From the physical point of view, the following questions are proposed.
● Why is special equipment needed to explore underwater depths?
● How does the oxygen needed for fish to breathe get into the water?
● Why do fish need a swim bladder?
● How is the diving depth of fish regulated with it?
● Why are the stems of underwater plants soft and flexible?
● How to measure the depth of water under a ship?
● Why are fish, sharks, dolphins streamlined?
● Why is oil pollution of water dangerous?
Expert biologists characterize the animals that students see on the screen.
◄ Expert - biologist.
More than 160 thousand species of animals and about 10 thousand species of algae live in the world's oceans. Algae play a significant role in providing oxygen to the inhabitants of the waters; a person consumes them for food, uses them as fertilizers, and iodine, alcohol, and acetic acid are obtained from them. 85 million tons of fish are caught annually in the World Ocean. This is not only 1% of world food production, but also 15% of animal proteins consumed by mankind. The ocean shelf contains the greatest reserves of oil and gas, iron-magnesium ores and other minerals.
◄Oceanologist
Sharks - from a number of lamellar-gill fish. Body length from 0.2 m (black shark) to 20 m (giant shark). About 250 species are known. Widespread mainly in tropical seas. Object of fishing (meat is eaten, fish oil is obtained from the liver, glue is obtained from the skeleton) Large sharks (Whale, blue) are dangerous to humans.
◄Physiologist
An electric ramp can generate a voltage of 650 V. An interesting recipe for electrotherapy with an electric ramp was described by an ancient Roman healer in the 1st century AD: “Headache disappears if a live black skate is placed on a painful point and held until the pain disappears.” The ancient Greeks believed that electric stingrays could "bewitch" the victim, and called them "narke" - i.e. one that causes numbness, hence the name "drug".
◄Zoologist
The span of manta fins reaches 8 m. Weight is about 3 tons. He has small horns on his head, with which he drives small fish into his mouth. For these "horns" they were nicknamed "sea devils"
◄ Geneticist
The moray eel has a snake-like body 3 m long. There are sharp teeth on the jaws, which were previously mistakenly considered poisoned. Skin without scales. Moray eels usually hide in the crevices of underwater reefs and rocks, waiting for their prey - fish, crabs, cuttlefish. The moray eel itself does not attack a person, only if it is disturbed. The meat of some species of moray eel causes severe poisoning if it is eaten.
◄ Biophysicist
The specific gravity of cartilaginous fish is greater than the specific gravity of water, so they must constantly move their tail so as not to fall to the bottom. In addition, underwater currents help them move in the water.
◄Environmentalist
Every year 5-10 million tons of oil enters the World Ocean. To understand how much this is, we can give the following example: 1 liter of spilled oil blocks the access of oxygen to 40 thousand liters of sea water. We know that the density of oil is less than the density of water, so it spreads over the surface of the water and creates a thin film on its surface. According to American scientists, 1/3 of the ocean is covered with oil. Not only that, without access to oxygen, fish that breathe it can die, but this is a real misfortune for waterfowl. How do you figure out why?
◄Microbiologist
The oil slick does not let the sun's rays through, as a result of which plankton, the basis of food for marine life, ceases to multiply. Liquid and solid household waste (feces, synthetic films and containers, plastic nets) enter the seas and oceans. These materials are lighter than water, and therefore float on the surface for a long time. In fish that have survived in such conditions, mollusks and crustaceans have a reduced growth rate. Often the species composition of organisms also changes.
- Summing up the lesson
The teacher sums up the lesson, once again focuses on the environmental problems of the oceans associated with human life. Thank you all for your hard work.
