Annual life cycle of amphibians: phenology, daily and seasonal activity, wintering. Annual life cycle of amphibians Annual cycle of amphibians diagram

The influence of seasonal changes in nature on the life of amphibians. The annual life cycle is well expressed in amphibians living in temperate latitudes with sharp seasonal changes in living conditions.

In early autumn, when average daily temperatures drop to +12 ... +8 °C, amphibians move to wintering grounds, and with a further decrease in temperature in September - early October, they hide in shelters. In search of wintering places, individual individuals move many hundreds of meters.

Lake, pond and common frogs hibernate in water bodies, gathering several dozen individuals together, hiding under stones, among aquatic plants, and burrowing into silt. They choose deep areas where water bodies do not freeze to the bottom.

Toads, toads, newts, salamanders hibernate on land: they climb into pits, rodent burrows, hide in the dust of rotting stumps, under stones. In winters with little snow, when the earth freezes to a great depth, more amphibians wintering in it die than in water bodies, since body temperatures below -1 ° C are fatal for them. At low positive temperatures, wintering amphibians are in a stupor: their metabolism sharply decreases, the number of respiratory movements and heart contractions decreases, and oxygen absorption is reduced by two to three times.

In spring, with the onset of warm weather, at the end of March and in April, amphibians switch to an active lifestyle, leave their wintering grounds and head to breeding grounds. These spring movements are quite amicable, the animals overcome hundreds of meters, reaching small, well-heated by the sun reservoirs.

After breeding, brown frogs, toads, tree frogs move to their usual summer habitats in meadows, fields, vegetable gardens, orchards, etc. Tritons and toads spend another 2-3 months in water bodies, and then move on to land.

Reproduction of amphibians. Amphibians breed in shallow, well-warmed areas of water bodies. On warm spring evenings, at the end of April and in May, loud croaking sounds are heard from ponds and rivers. These "concerts" are arranged by male frogs to attract females.

The reproductive organs in male amphibians, like in fish, are the testes, and in females, the ovaries. They are located in the body cavity, by the time of reproduction they increase many times over. The matured eggs in the ovaries enter the oviducts. While moving along the oviduct, the eggs are covered with a transparent mucous membrane and are brought out through the cloaca. In males, the testes have oval shape produce many motile spermatozoa. Seminal fluid, rich in spermatozoa, enters the cloaca through the vas deferens and is excreted outside. Fertilization in amphibians is external. Clusters of fertilized eggs are attached to aquatic plants or float in separate lumps near the surface of the water. Ribbons of fertilized toad eggs, like individual newt eggs, stick to the leaves of aquatic plants.

The development of amphibians. The development of the frog embryo (Fig. 137) in the egg lasts about a week and a half. Then the embryo breaks the shell of the egg, and the larva, the tadpole, comes out. By appearance and the lifestyle of the tadpole is similar to a fish. He has gills, a two-chambered heart and one circle of blood circulation, lateral line organs.

Rice. 137. Development of a frog: 1 - caviar; 2 - exit of the tadpole from the egg; 3,4 - tadpole with developed external gills; 5 - tadpole with internal gills; 6 - the appearance of the hind limbs; 7 - the appearance of the forelimbs; 8 - resorption of the tail; 9 - landfall

In the process of development, important changes occur in the tadpole. The hind limbs develop first, and then the forelimbs. Lungs appear, and the tadpole more and more often rises to the surface of the water for breathing. In connection with the development of the lungs, a second circle of blood circulation is formed, the heart becomes three-chambered. The tail is gradually decreasing. The tadpole becomes like an adult frog. The frog from plant nutrition passes to the consumption of animal food (becomes carnivorous) and leaves the reservoir. From the time of laying eggs to the transformation of a tadpole into a frog, 2-3 months pass.

Adult frogs do not have a tail. They begin to breed at the age of 3-4 years.

Origin of amphibians. Reproduction of amphibians occurs in the same way as in bony fish. Tadpoles look more like fish than their adult parents. They have all the same organs that fish need to live in the water. All this indicates that amphibians descended from some ancient bony fish.

It is known that some ancient bony fish used limbs (paired fins) to crawl from one reservoir to another. They developed primitive lung sacs, which the fish used to breathe when there was a lack of oxygen in the water and when water bodies dried up. The greatest similarity exists between the ancient amphibians that appeared about 350 million years ago (Fig. 138), and the ancient freshwater lobe-finned fish - ripidistia. Their sten can be judged by the marine coelacanth coelacanth fish that has survived to this day (see Fig. 126).

Rice. 138. Ancient amphibian

It is important that the skeleton of the paired fins of lobe-finned fish is similar to the skeleton of the five-fingered limb of amphibians (Fig. 139).

Rice. 139. Skeletons of the anterior paired limb of a lobe-finned fish (1) and an ancient amphibian (2)

Apparently, it was from the ancient ripidistians that the first amphibians (ichhyostegids) arose, in external structure resembling modern tailed amphibians. They had limbs characteristic of terrestrial vertebrates and well-developed limb girdles. The wide flattened head, widely diverging ends of the jaws suggested that they sucked air into the lungs by lowering the bottom of the oral cavity. Ichthyostegids have preserved typical fish features: a skull with typical fish bones; remains (rudiments) of the gill cover; long tail and lateral line organs.

It is assumed that the primitive ancient amphibians led an aquatic lifestyle, fed and multiplied in the water. However, they could go on land and breathe air with a lack of oxygen in the water, drying up of water bodies. All this allowed us to call them four-legged fish. Ancient amphibians gave rise to modern newts, salamanders, frogs, toads.

Amphibians are dioecious animals that breed in water. Fertilization is external. Females spawn, males secrete seminal fluid. Development with transformation: fish-like tadpoles emerge from the eggs, which in the course of development turn into an adult amphibian. The way of life of amphibians changes depending on seasonal changes in living conditions. Amphibians evolved about 350 million years ago from the ancient lobe-finned fish ripidistia. The first primitive amphibians retained many typical fish features. They gave rise to modern amphibians.

Lesson learned exercises

  1. Describe the annual life cycle of a frog in temperate latitudes.
  2. Name the similarities in the reproduction of amphibians and fish.
  3. What is the similarity of a tadpole with fish? What does this confirm?
  4. What are the changes in the external and internal structure occur in the tadpole during development?
  5. Consider the main stages of the origin of modern amphibians.
  • Yearly life cycle
  • and the origin of terrestrial water
  • NOU "Diveevo Monastery Orthodox Secondary School"
  • To ensure that students acquire knowledge about the reproduction and development of amphibians;
  • To get acquainted with different points of view on the origin of amphibians.
  • Compare the structure, lifestyle of the frog and the head.
  • "Reproduction and development of the frog"
  • In the course of acquaintance in the lesson with the reproduction and development of amphibians, fill in the table. Draw your own conclusions.
  • signs
  • 1. Habitat
  • 2. Way of movement
  • 3.Parts of the body
  • 4.Feeding method
  • 5. Respiratory organ
  • 6. Structure of the heart
  • 7. Circles of blood circulation
  • 8. Sideline
  • 9. Chord
  • Frog
  • Tadpole
  • Singing male in the nest
  • Male tree frog with swollen throat resonator.
  • In the mating season, the male of this frog looks for a small hollow in one of the trees, in which rainwater has accumulated - a place for the development of future tadpoles. Having chosen a suitable “apartment”, the male begins to make mating calls that attract females. How else can two tiny frogs find each other in a dense tropical forest?
  • Amphibian eggs, usually devoid of specialized membranes that prevent drying out, as a rule, develop in water (there are exceptions, but they are not many). The larva has the features of a typical aquatic animal: it has gills and cartilaginous gill arches supporting them, a two-chambered heart, one circle of blood circulation, lateral line organs that remain in the adult state only in some typically aquatic forms (the clawed frog, a number of salamanders), and in newts they reappear when they go into the reservoirs for spawning. The movement of the larvae is carried out not by lever limbs, but by a powerful caudal fin.
  • In most amphibians, the initial development of the embryos occurs in the same way as in fish. Amphibians usually lay their eggs in water. Fertilization in most cases occurs after the laying of eggs, already in the water. Amphibian eggs are surrounded by a dense layer of gelatinous substance.
  • Why do you think?
  • Frog caviar laying
  • lake frog
  • After the end of the initial stage of development, the larva breaks through the gelatinous membrane and begins an independent life in the water.
  • The larva has a flat flattened head, a rounded body and a long oar-like tail, trimmed above and below with a leathery fin. External gills grow on the head in the form of tree-branched processes. In the larvae of tailed amphibians - tadpoles - after a while these gills fall off, and internal gills form instead. Later gill slits are tightened with a fold of skin.
  • A small tadpole in appearance is very similar to a fish fry. It feeds by scraping nutrients from the surface of plants or dead debris. The tadpole grows and develops rapidly. Little by little, the limbs begin to develop (the hind limbs are immediately visible in tadpoles, while the front ones are hidden under a fold of skin at first). Later, lungs develop from the abdominal wall of the esophagus, adult animals breathe with lungs and skin, and larvae with gills and skin. The tadpole stops eating for a while, its intestines become shorter and adapt to the digestion of animal food, the tail quickly shortens and dissolves - the larva turns into a young frog.
  • In the process of transformation into an adult animal (metamorphosis), the larva loses some of these features, but many adult amphibians retain a number of aquatic features: an abundance of mucous glands that provide skin respiration; weak ossification of the skeleton, that is, the presence in it of an abundance of cartilaginous elements; external fertilization, in connection with which many species have developed mating behavior necessary to synchronize the release of reproductive products by individuals of different sexes, etc.
  • Frog after metamorphosis
  • Unlike other vertebrates, amphibians, or amphibians, in their individual development undergo a transformation that is widespread in vertebrates: after hatching from an egg (egg), they are similar to fish and have gills, and then gradually turn into animals with pulmonary breathing.
  • Checking the filling of the table
  • Axolotl, as scientists have established, is a larva of the American ambistoma.
  • Distributed in North and Central America.
  • These amazing amphibians, being larvae, are already capable of reproduction - this phenomenon is called "neotenia". In addition, they are capable of regenerating lost body parts such as limbs and internal organs.
  • Larva - axolotl. 5 species in the Red Book of the International Union for Conservation of Nature and Natural Resources.
  • In 1933, teacher Chetverikova N.K. Koltsov showed, neoteny in the animal kingdom is widespread and plays an important role in progressive evolution. It leads to morphological simplification (but at the same time richness is preserved genotype.)
  • The close connection of amphibians with water, as well as the structure and lifestyle of their larvae, indicate the origin of these animals from fish. It was possible to find the fossilized remains of extinct amphibians. Their skin had scales, and the skull looked like the skull of lobe-finned fish. Scientists have found that the first amphibians appeared more than 300 million years ago. Their ancestors were freshwater lobe-finned fish. Comparison of the fin skeleton of the modern coelacanth coelacanth fish and the fin imprints of extinct lobe-finned fish with the amphibian limb skeleton indicates their great similarity. It is believed that the extinct freshwater lobe-finned fish had lungs that developed from the swim bladder. They lived in small lakes and rivers, could crawl from one reservoir to another with the help of their muscular fins. The first terrestrial vertebrates, the ancient tailed amphibians, originated from these fish. Tailless appeared later and descended from ancient tailed amphibians. 200 million years ago, the Earth was covered with huge swamps. This period was the most favorable for the development of amphibians. Many of them reached a length of 5-6 m (the largest modern amphibian - a giant salamander living in Southeast Asia, reaches a length of 1.5 m).
Two stages in the transformation of fish into terrestrial vertebrates. A. Devonian lobe-finned fish with a primitive lung. B. Devonian amphibian Ichthyostega, about 90 cm long. Note feet with toes still webbed like fins.
  • Two stages in the transformation of fish into terrestrial vertebrates. A. Devonian lobe-finned fish with a primitive lung. B. Devonian amphibian Ichthyostega, about 90 cm long. Note feet with toes still webbed like fins.
  • Creationism (from the Latin creation - creation, hence Creador - Creator, Creator).
  • Creationists deny the principle of spontaneous ascent from lower forms of matter to higher ones.
  • They believe that without specially directed energy, bricks will never spontaneously form into a house, for example, without the action of a hurricane.
  • The transformation of invertebrates into fish is
  • fundamental change in its structure. An elementary plastic creature (worm, jellyfish) or a creature with a soft body and a hard shell turns into a fish with gills and a hard skeleton! Such a process, evolutionists believe, must take at least tens of millions of years, producing billions of transitional forms, none of which have been found anywhere.
  • “I must say that the fish known to me come quite definitely from nothing,” writes the president of the Linnean Society, ichthyologist E. White.
  • Comorian coelacanth at the London Museum
  • Then, in the Upper Devonian, also without intermediate links
  • amphibians appear. "Thousands of thousands of remains of certain genera of fish,
  • amphibians and reptiles are found on every continent."
  • Is it possible to build evolutionary chains from these remains?
  • "The transitional forms between the fins of fishes and the limbs of tetrapods are not
  • known. All fossil forms are uniquely either fish,
  • or amphibians."
  • Detachment coelacanths. Coelacanth
  • Coelacanths are found near the Comoros, in Indonesia and in the Gulf of Sudan (South Africa); in some other regions they are sometimes carried by the powerful Mozambique Current.
  • The “long-extinct” coelacanth fish coelacanth, together with the Devonian lobe-finned fish, was considered the ancestor of the ichthyosteg (extinct amphibians, outwardly similar to modern crocodiles and salamanders). It was assumed that the lobe-finned fish, crawling on their fleshy fins from a reservoir to a reservoir, gradually rebuilt for life on land.
  • In 1938, they managed to catch the coelacanth alive and, after examining it, made sure that it was just a fish that did not at all strive for life on land, but was adapted to living exclusively at great depths.
  • The supposed lungs were not found, as well as nothing else that distinguishes coelacanth from fish
  • coelacanth
  • fossil coelacanth Caridosuctor populosum, lived approximately 320 million years ago
  • On the one hand, the resemblance of a tadpole to a fish is proof of the origin of amphibians from fish, according to the evolutionary point of view.
  • On the other hand, the development of the tadpole does not end at this stage, but a series of successive stages of development transforms it into an adult amphibian.
  • What are the sex glands in amphibians called?
  • Why do frogs lay their eggs in shallow water?
  • What are the signs inherited by amphibians?
  • from fish, according to an evolutionary point of view.
  • Which view of origin do you think is the most accurate?
  • And why?
  • Conclusion:
  • The development of amphibians is carried out with metamorphosis (transformation);
  • The similarity of a tadpole with a fish is proof of the origin of amphibians from fish,
  • according to an evolutionary point of view.
  • The characteristic features of the structure of the tadpole are only an adaptation to the aquatic
  • a way of life that cannot be mistaken for transitional forms.
  • Section 38
http://ru. wikipedia.org/wiki/ Theory_of evolution
  • http://ru. wikipedia.org/wiki/ Theory_of evolution
  • http://ru.wikipedia.org/wiki/Creationism
  • Animal life, vols. 1–2. - M .: Education, 1968.
  • Lasukov R.Yu. Water dwellers. Pocket identifier. – M.: Rolf, 1999:
  • Lipin A.N. Fresh water bodies and their life. – M.: Uchpedgiz, 1950.
  • Mamaev B.M. Identifier of insects by larvae. - M.: Enlightenment, 1972.
  • Raikov B.E., Rimsky-Korsakov M.N. Zoological excursions. – M.: Topikal, 1994.
  • Vertyanov S. Origin of life: facts, hypotheses, evidence.
  • - Holy Trinity Sergius Lavra, 2006.
  • Todd G.T. //American Zoologist.-1980.-20(4);White E.//Proceedings of the Linnean Society.London.-1966.-177:8
  • Carrol R.L/ Vertebrate Paleontology and Evolution.-Freeman and Co., New York, 1988.-P.4
  • . Vyatkin Yu.S., Zhuravlev V.B., Kiselev V.D. Darwin's evolutionary theory and modernity // On the website of the Altai state university (www.asu.ru), 2004.

§ to form knowledge about the annual life cycle § to form knowledge about the annual life cycle of amphibians, the process of their reproduction using the example of a frog;

§ broaden horizons;

§realize environmental education students of amphibians, the process of their reproduction on the example of a frog;

§ develop cognitive interest in the subject;

§ broaden horizons;

§ develop the ability to compare, draw up diagrams, tables;

§ to carry out environmental education of students

Download:

Preview:

To use the preview of presentations, create an account for yourself ( account) Google and sign in: https://accounts.google.com


Slides captions:

The annual life cycle of amphibians Prepared by: biology teacher MBOU Buturlinovskaya secondary school Klimova Svetlana Vitalievna.

Objectives: to form knowledge about the annual life cycle of amphibians, the process of their reproduction using the example of a frog; develop cognitive interest in the subject; expand horizons; develop the ability to compare, draw up diagrams, tables; carry out environmental education of students

Actualization of knowledge (1) 1.Individual survey: - Make a diagram of the digestive system of a frog. - Draw a diagram of the nervous system of a frog - Compare the circulatory system of fish and amphibians.

Actualization of knowledge (2) - answer the question: why can amphibians breathe atmospheric air, and what is the mechanism of their breathing? - sketch excretory system frogs. - work with interactive cards.

Class tasks Testing 1. Amphibians breathe with the help of: a) gills b) only lungs c) only wet skin d) lungs and wet skin 2. Amphibians are characterized by the following features: body c) no neck d) limbs of three sections 3. In connection with landfall, amphibians appear: a) skull and spine b) eyelids c) eyes and nostrils d) eardrum 4. Unlike fish, amphibians appear: a) stomach b) liver c) salivary glands d) pancreas 5. The cloaca opens: a) digestive system b) excretory c) reproductive system d) circulatory

Assignments to the class Signs Amphibious Fish Habitat Parts of the body Organs of movement Respiratory organs Structure of the heart Blood circulation Nervous system Structure of the brain Reproductive organs Fertilization Development 3. Fill in the table

The study of new material 1. The annual life cycle of amphibians The annual life cycles of amphibians are well expressed in temperate latitudes with sharp seasonal changes in living conditions. When the average daily temperature drops to +12, +8C, amphibians move to wintering grounds, and when the temperature drops further in September - early October, they hide in shelters. At the same time, individual individuals can move in search of wintering places for many hundreds of meters. Lake, pond and grass frogs winter in water bodies, gathering several dozen individuals together, hiding under stones, among aquatic plants, and burrowing into silt. They choose the deepest areas where the reservoirs do not freeze to the bottom. Toads, toads, newts, salamanders hibernate on land, climb into pits, rodent burrows, hide in the dust of rotting stumps, under stones, etc. During the wintering period, amphibians are in a stupor, their metabolism sharply decreases, oxygen decreases by 2-3 times, the number of respiratory movements and heart contractions. Do frogs grow in winter???

2. Reproduction of frogs In early spring, with the first rays of the warm sun, amphibians wake up from hibernation and start breeding. During this period, males develop paired sacs on the sides of their heads - resonators that amplify sounds. The louder and more melodious the sounds made by the male, the more chances they have to win a girlfriend. At the time of reproduction, amphibians break into pairs. The female spawns large eggs into the water, which are called caviar. A nearby male releases a liquid containing spermatozoa onto them. This means that the frog has external fertilization.

3. Development of the frog After some time, the shell of the eggs swells, turning into a gelatinous, transparent layer. Underneath is a fertilized egg. Its upper side is dark, due to which it heats up strongly from the sun. Very often, lumps and ribbons of caviar float to the surface of the water, where the temperature is higher.

The development of the pond frog As in most amphibians, it occurs with metamorphosis. Also, like in fish, the development of amphibians takes place in the water. Therefore, they do not form any embryonic membranes. After about one to two weeks, frog larvae - tadpoles - emerge from the eggs. Outwardly, they resemble fish fry. They have a long, flattened tail, as well as a lateral line. Tadpoles breathe with external skin gills, which eventually become internal. Unlike adult frogs, they have only one circle of blood circulation, and venous blood is always in the heart. The first days of life, tadpoles feed on the yolk of eggs, then their mouth separates, and they begin to feed on their own. They feed on a variety of algae, protozoa, and small aquatic invertebrates.

Development of amphibians

Geoffroy Saint-Hilaire He said that anyone who wants to be convinced of the validity of evolutionary ideas can see with his own eyes a miracle every spring - a repetition of the emergence of vertebrates on land. He considered this miracle the transformation of a tadpole into an adult amphibian.

Make a diagram of the "Stages of development of a frog" Stages of development of a frog: spermatozoon Unfertilized egg Fertilized egg Multicellular embryo tadpole Adult animal

4. Reproduction of other amphibians. Individual student reports Exotic animals such as the marsupial tree frog and the Surinamese pipa toad rear their offspring in special cells in the skin of the back, so that at the time of hatching and immediately after it, you can see several babies crawling on the back of the female. And the male Chilean frog is completely original - he carries tadpoles in his vocal sac

5. "Return home" or homing Small tree frogs (relatives of frogs) live on the trunks of trees and shrubs, but gather near water bodies for breeding. Such a case is known. A lot of tree frogs always gathered near one small pond. But one spring, the surrounding fields were leveled, the pond was filled up, and the entire area was cleared of shrubs. And what about tree frogs? After some time, already out of the blue, on the arable land, where there used to be a pond, about three dozen males were found singing a mating song among the furrows. But there were no external signs by which one could find a place! It is worth adding that other amphibious toads also unmistakably come to the former pond, even if it is drained.

Fixation 1 Comparative characteristics of the tadpole and frog Signs Tadpole Frog Habitat Mode of movement Body parts Respiratory organs Number of circulation circles Number of chambers in the heart Lateral line Chord

Fixation 1 Comparative characteristics of the tadpole and frog Signs Tadpole Frog Habitat aquatic Aquatic + terrestrial-aquatic Habitat Swimming with the tail Jumping and swimming with the hind limbs Parts of the body Head, trunk, tail Head, trunk, limbs of the terrestrial type Respiratory organs gills Lungs + skin Number of circulation circles 1 2 Number of chambers in the heart 2 3 Lateral line + _ Chord + _

2. Solving biological problems (1) Problem №1 In the eggs of most tailless amphibians, the heavier part of the egg is always turned downwards. The upper dark part of the egg, on the contrary, is turned upwards. What does this mean for the development of the animal? Task number 2 Tadpole frogs in appearance are more like fish than their parents. They have gills, lateral line organs, and a tail fin. Are there signs of fish in the internal structure of the tadpole? If so, which ones? Task №3 The tadpole, turning into a frog, does not eat anything. There is a deep restructuring of the digestive system. Where then does the tadpole get the energy it needs to turn into a frog? Task No. 4 In order to find out how to regulate the growth of the population, the following experiment was done. Different numbers of tadpoles were placed in two tanks of the same volume. In the first aquarium there were twice as many tadpoles, here they grew slowly. From the first aquarium, some water was poured into the second, without changing the number of tadpoles in it. As a result, their growth and development, previously intense, has clearly slowed down. Draw a conclusion from this experience.

Task number 5 Is it possible to take an x-ray chest frogs? Problem No. 6 The pond frog, which lives in and near water bodies, is active during the day, and the grass frog, which lives in swamps and meadows, is active at dusk. Why? Task number 7 Why are the muscles of the hind limbs more developed in the frog than the forelimbs? Task No. 8 It is noticed that a frog, having grabbed a large insect, closes its eyes and draws them into the oropharynx. How can these two phenomena be related: the capture of prey by the mouth and the retraction of the eyes into the oropharynx? 2. Solving biological problems (2)

FROG-COWROOM - a frog endowed with supernatural properties, a toad; damn girl. Toads are able to suck out cancerous poisons from the body. (Rural superstition of the 18th century). The frog was often seen as the spirit of the deceased, the soul of a child buried unbaptized; can jinx a person or animal; the appearance of a frog in the house is a harbinger of the arrival of unwanted guests, misfortune, death in the house; Folk omens and superstition

It's interesting...that the first monument to frogs was built at the Sorbonne University of Paris in the 19th century, at the urging of the famous French naturalist Claude Bernard. The second monument was erected relatively recently in Tokyo by medical students. So scientists thanked their experimental animals

General conclusions In general, amphibians can be divided into aquatic and terrestrial species. Some go far from water bodies, returning to them during the breeding season. Others spend their entire lives in the water. Some amphibians lead a burrowing lifestyle.

The metabolism of amphibians is slow. All amphibians are cold-blooded animals; in winter they hibernate. However, the maximum activity in species living in temperate latitudes is observed at night - at this time there are no scorching rays of the sun. The constant evaporation of moisture from the surface of the skin makes them dependent on the humidity of the environment. Tropical species, waiting out the drought, burrow into the soil. The pond frog is a dioecious animal. Its reproduction occurs in early spring. Development occurs with metamorphosis, without the formation of embryonic membranes. The larva of a pond frog is called a tadpole.

Homework: P. 38 (KBK) Answer questions (p. 186) Prepare reports about the axolotl, toad - aga and frog - bull (individual tasks).

Sources used http://www.lenagold.ru/fon/clipart/l/lagu.html- Lenagold - Clipart- Frogs http:// www. alphabet. info /13 files / image 007,008,009. S.A. Molis Book for reading on zoology, M. Enlightenment 1986 V.M. Konstantinov, V.G. Babenko, V.S. Kuchmenko Biology Animals Grade 7, M. "Venta-Graf" 1999 N.F. Bodrova Studying the course "Zoology". Lesson planning Voronezh 2000


Annual cycles in amphibians are most clearly expressed in areas with a sharp seasonal change in living conditions: in temperate latitudes, in mountains, deserts and semi-deserts. In humid tropical forests, biological seasonality is smoothed out. An unfavorable period of the year (winter or a period of drought) amphibians spend in a stupor, the duration of which is determined by the length of the period. In temperate latitudes, the determining factor is temperature, in the tropics and subtropics - humidity. These factors act directly and through the deterioration of nutritional conditions. They also have a decisive influence on the geographical distribution of amphibians.

With a decrease in the average daily temperature to 8-12 ° C and at night temperatures of 3-5 ° C, amphibians move to wintering places, and with a further decrease in temperature in September - early October, they hide in winter shelters. Green (lake and pond) and grass frogs winter in water bodies (rivers, streams, lakes, peat quarries, etc.), gathering in groups in deeper non-freezing areas (under stones, in algae thickets or burrowing into silt). Moor frogs and tree frogs usually hibernate on land, but some individuals can also hibernate in water bodies. Toads, toads, spadeworts, newts, salamanders hibernate on land, climbing into pits, rodent burrows, rotten roots, under stones, stumps, etc.

During the wintering period (or during a drought), the level of metabolism in animals sharply decreases, oxygen uptake is reduced by 2-3 times. When body temperature drops below -0.5-1 ° C, amphibians usually die. The daily rhythm of amphibian activity is determined by weather conditions, primarily temperature and humidity. In warm summers, toads and newts living in the water, and green frogs staying on the edge of the coast and in shallow water are active around the clock. Terrestrial species (toads, brown frogs, tree frogs, etc.) are active at dusk and at night, when the heat subsides and air humidity increases; on cloudy rainy days they are active during the day. On cool nights, these species are most active at dusk - in the morning and evening.



66. Environmental groups amphibians (hydro-, chthon-, edapho-, dendrobionts).

The life environment of amphibians is very diverse. Among them there are purely aquatic forms that never come to land. Most of them belong to the tailed amphibians (proteas, sirens) - hydrobionts.

Most anurans lead a semi-aquatic lifestyle. During the breeding season, they live in water bodies. Many also overwinter in the water. Outside of the specified time, these species live on land and often leave water bodies for long distances. Such are toads, salamanders. Green frogs spend a lot of time outside the water, but they do not go far from water bodies and, in case of danger, hide in the water with one jump - chthonobionts.

Among the tailless, there are many who live in trees. For the most part, these are the inhabitants of tropical forests, which breed on trees, using the water accumulated in hollows and on large leaves to lay eggs - dendrobionts.

Species burrowing in the ground - edaphobionts - these include almost all legless, which are inhabitants of the soil thickness, burrowing into the ground. For most, the soil is just a place of temporary residence.

67. The role of amphibians in ecosystems. Practical value in various industries National economy. Importance of amphibians as laboratory animals.

All amphibians are useful to humans to one degree or another, primarily because they eat many harmful invertebrates (molluscs, insects and their larvae, including mosquitoes, etc.) that damage agricultural and forest crops or carry diseases to humans and domestic animals. In terrestrial species, food objects are usually more diverse than in species with an aquatic lifestyle. The common frog eats 6 harmful invertebrates per day on average. With a population of 100 frogs per 1 ha, they will destroy more than 100 thousand pests during the period of summer activity. Amphibians often eat invertebrates with an unpleasant odor or taste, and hunt at dusk and at night. Therefore, their activity complements the beneficial activity of birds. However, the benefits of amphibians are generally small, as they reach large numbers in only a few landscapes. Caviar, tadpoles and adults of predominantly aquatic species are intensively eaten by many commercial fish, ducks, herons and other birds. Amphibians make up an essential part of the summer diet of some fur-bearing animals (spanking, polecat, etc.); otters also feed on frogs in winter.

In a number of countries, large salamanders and frogs are used as food by people (France, Southeast Asia, America, etc.). There are farms in the US that breed the bullfrog; the hind legs (a pair weighing 250-400 g) go on sale, and the rest of the carcasses are processed for livestock feed. The importance of amphibians as laboratory animals used in a wide variety of biological and medical research is very great. In a number of countries Western Europe the number of many amphibians has declined sharply. The reasons for this are varied: habitat changes as a result of land reclamation and economic development of territories, water pollution in spawning waters, human persecution, etc. Therefore, in some countries special laws have now been adopted that protect amphibians and prohibit their prey. For laboratory purposes, axolotls are bred, attempts are being made to artificially breed other species.

Only in some places amphibians have a negative value. So, eating juvenile fish, some damage in fish farms can be caused by green frogs - pond and especially lake frogs; in some fish farms in the Volga delta, they destroy up to 0.1% of fry. However, this damage is covered by the extermination of aquatic insects that eat eggs and juvenile fish. It should be borne in mind that amphibians themselves serve as food for fish. Amphibians can also have some negative value as intermediate hosts of worms that infect birds and fur-bearing animals, as well as temporary hosts of the causative agent of tuleria.



We recommend reading