Lesson topic "Caring for offspring"

During the classes:

I. Organization of the beginning of the lesson.

I I ... Introduction to the topic of the lesson:

1.Frontal conversation:

- What is fitness?

What forms of fitness do you know? Name them and give examples

How do you know that fitness is relative?

2. Biological dictation.

Insert a term that means this definition.

1. The process of survival of the individuals most adapted to the given conditions is called ...

2. Coloring that helps to hide in the environment is called ...

2. Acquisition of resemblance to some object is called ...

3. The similarities between unprotected and protected species are called ...

4. Any ... is relative.

Answer: natural selection, protective coloration, disguise, mimicry, fitness.

III . Formation of new knowledge:

We have identified: morphological, physiological, biochemical, ethological adaptations. Animals with a highly developed nervous system have ethological adaptations. Such adaptations are manifested in various forms of animal behavior aimed at the survival of individual individuals and the species as a whole. Distinguish between congenital and acquired ethological adaptations, congenital include mating behavior, caring for offspring, avoidance of predators, migration. Today we will focus on taking care of the offspring.

How does it manifest itself in representatives of various classes of animals and what does it serve?

1 slide. Caring for offspring is a chain of successive reflexes developed in the process of evolution, ensuring the preservation of the species.

How does caring for offspring manifest in different animals?

3 slide. Class Insects ... In those species of insects that take care of the offspring, it is expressed in the fact that parents seek to provide their offspring with a food source. A striking example of this is scarab beetles. They make balls from fresh manure and roll them back a certain distance. Here they burrow into the ground, and are either eaten by the beetles themselves, or an egg is laid on it. The larva that emerged from it is provided with delicious food for the entire period of its development. We see such a phenomenon in the cabbage butterfly, wasps, moths, and wasps.

4 slide. Class Arachnids. The female karakurt, a deadly poisonous spider that lives in Central Asia, turns out to be a rather caring mother. The eggs, placed in an egg cocoon, are suspended from the ceiling of the cave in which the spider lives. They are under reliable protection, first by the mother's poison, and then, when she dies, they hibernate under a dense shell.

5 slide. Crustacean class. River crayfish also do not abandon their offspring. They carry eggs with them. When the rats hatch from the eggs, they attach to the abdominal legs of the mother. And there they remain until they become independent.

2.Class Pisces.

6 slide. For many millions of years, fish have developed amazing ways of caring for their offspring. Small fish tilapia carries caviar and fry in its mouth! The fry calmly swim around their mother, swallow something, wait. But as soon as the slightest danger arises, the mother gives a signal, sharply moving her tail and trembling in a special way with her fins, and ... the fry immediately rush to the shelter - the mother's mouth.

7 slide. Freshwater fishbitterness at the time of reproduction, the ovipositor grows. The female lays eggs in the mantle cavity of bivalve molluscs. Here fry of bitter weed also develop. Some fish build nests for fry. From foam they build nests of macropods, gourami, labyrinth fish.

8 slide ... The male of the three-spined stickleback also builds a nest for the female. When the nest is ready, the male drives the females there one after the other, which lay eggs there in several pieces. The females swim away, and the male guards the nest. It also refreshes the water by quickly moving the pectoral fins.

9 slide. Bottom fish Pinagora found in the Barents and White Seas. At low tide, when the eggs are stranded, the pinagora collects water in the stomach, sprinkles the eggs from the mouth.

10 slide ... In seahorses, the male takes care of the offspring. The female lays eggs for him in the brood pouch under the tail, where he bears them. Even after hatching the fry, the male carries them in a bag for some time.

3.Class amphibians .

11 slide. Most of the amphibians that lay eggs do not show any behavior associated with caring for their offspring, and after laying eggs, they leave the reservoirs, leaving their offspring to fend for themselves. However, for example, the bullfrog inhabiting the Caribbean islands for a long time protects the eggs and the larvae hatched from it. Moreover, the male monitors the water level in the drying puddles in which they develop, and, if necessary, deepens the puddles or digs a groove into the adjacent puddle, through which he then drives the tadpoles into it. Tree frogs-tree frogs. Living in the crowns of tropical forests, many tree frogs are faced with the problem of finding water for their offspring. Therefore, among the representatives of this family there are those who have developed very interesting forms of caring for offspring. In some species, parents build special nests on plants that replace reservoirs for larvae, in others they build artificial reservoirs, in others they carry eggs and larvae on themselves.

12 slide. So, tropical leaf-climbing tree frogs lay eggs on the leaves of trees and guard the clutch until the larvae hatch. The tadpoles hatched from the eggs crawl onto the damp back of the male, and he transfers them one by one to the micro-water tanks located right there on the trees, in the leaf axils. In the absence of suitable water reservoirs, tadpoles remain on the back of the male during the entire period of metamorphosis. He periodically bathes with them in larger puddles. In some leaf climbers, males constantly transfer tadpoles from one bath to another, so that they, having eaten all the food in a small reservoir, do not starve. In one species of leaf climbers, the female carries the tadpoles to the ponds located at the base of the leaves. Then she regularly visits the cubs and lays several unfertilized eggs in the water, which serve as food for the tadpoles.

13 slide ... The males of the European land toad-midwife are very caring fathers. Females lay eggs on land in the form of two cords containing 20-50 eggs each. The male helps the female to get rid of them. Grabbing the cords with the toes of his hind legs, he pulls them out and winds them around himself. An active male can obtain eggs from two or three females in this way. During the entire period of development of eggs, the male wears cords on itself. At the end of this period, the male goes in search of a reservoir, where the larvae hatch. After that, he frees himself from the emptied cords. Some species of frogs carry eggs and larvae in special brood pouches. During the breeding season, the skin forming the pouch changes its structure. Poisonous glands, pigment cells disappear from it, keratin is absorbed. It becomes tender and enriched with vessels. The pipa toad has become famous all over the world: it bears eggs on its back! In special cells that look like honeycombs. Such a lively baby carriage for 2 hundred places! Carries tadpoles on itself until they stand on their feet.

14 slide. In Australian marsupial tree frogs, pocket bags are located in the cloacal area of ​​males. The development of eggs takes place on the ground, and the larvae that emerged from it crawl into the bags of their parent themselves. The large yolk sac provides them with sufficient nutrition and allows them to stay in brood pouches until metamorphosis. In a number of species, the bag, like a backpack, is located on the back or on the stomach.

4 reptiles .

Only a few reptiles guard their clutches, and almost none of them cares about the fate of the cubs born.

15 slide ... Moreover, many reptile mothers, on occasion, can eat their own offspring. The exception is crocodiles. They lay their eggs in peculiar nests of sand, clay and stones. carefully guard the "nest". And after hatching, the cubs are very carefully transferred to a safer place.

16 slide. Sea turtles make long-distance migrations in order to reproduce in certain areas of the sea coasts. They come to these places from different regions, often located many hundreds of kilometers away. For example, a green turtle, heading from the coast of Brazil to Ascension Island in the Atlantic Ocean, overcomes a distance of 2,600 km, fighting currents and keeping an accurate course. On land, the female moves with great difficulty, clumsily pushing her body forward and leaving behind a wide trail, similar to the track of a caterpillar tractor. She moves slowly and strives for one single goal - to find a suitable place for laying. Having got out beyond the surf line, the female carefully sniffs the sand, then rakes it and makes a shallow hole, in which she then, with the help of only her hind limbs, digs a pitcher-shaped nest. The shape of the nest is the same for all types of turtles. During the breeding season, females lay eggs two to five times; in clutch from 30 to 200 eggs. Parental behavior in turtles is absent, after laying eggs they go back to the sea, and, having hatched, the cubs make their way from the shore to the waterand further without parents

5.Class Birds.

It rarely happens that a hatching bird, or especially a bird near a brood, tries to hide unnoticed at the moment of danger. Large birds, protecting their brood, attack the enemy. At the same time, a swan can break a person's hand with a blow of the wing. More often, however, birds "drive away" the enemy. At first glance, it seems that the bird, saving the brood, deliberately distracts the attention of the enemy and pretends to be lame or shot. But in fact, the bird at this moment has two opposite aspirations-reflexes: the desire to flee and the desire to pounce on the enemy. The combination of these aspirations creates the complex behavior of the bird, which seems to be conscious to the observer. When the chicks hatch from the eggs, the parents begin to feed them. During this period, there is a strict division of labor.

17 slide. In black grouse, wood grouse and ducks, only one female leads the brood. The male does not care about the offspring. In the ptarmigan, only the female incubates, but both parents walk with the brood and "take away" the enemy from it. However, in brood birds, parents only protect the chicks and teach them to find food. The situation is more complicated in chick birds. As a rule, they feed both parents, but often one feeds vigorously, and the other is more lazy. In the Great Spotted Woodpecker, the female usually brings food every 5 minutes and manages to feed the chicks three times until the male arrives with food. And in the black woodpecker, the chicks are fed mainly by the male.

18 slide. In the sparrowhawk, only the male hunts. He brings prey to the female, which is always at the nest. The female tears the prey into pieces and closes the chicks with them. If the female dies for some reason, the male will put the prey brought on the edge of the nest, and the chicks will die of hunger. Small birds feed chicks very often. The great tit brings food to the chicks 350-390 times a day, the nuthatch 380 times, the belladonna swallow up to 500 times, and the American wren even 600 times. In search of food, the swift sometimes flies 40 km from the nest. He brings to the nest; not every midge caught, but a mouthful of food. It glues the prey into a lump with saliva, and when it arrives at the nest, it sticks insect balls deep into the throats of the chicks. In the first days, the swifts feed the chicks with such reinforced portions 34 times a day, and when the chicks grow up and are ready to fly out of the nest, only 4-6 times. But even after flying out of the nest, the chicks need parental care for a long time. Only gradually they learn to find and peck prey themselves.

6. Mammals.

19 slide. Caring for offspring in mammals can take many forms. A female echidna bears a laid egg in a pouch formed on its belly. The platypus incubates 1-2 eggs in a hole, where it arranges a nest for this.

20 slide. A female kangaroo carries her cub for 8 months in a pouch on her belly. A young kangaroo, who has grown up and has already begun to feed on its own, uses it as a temporary refuge for a long time. In the Florida Oceanarium, a female bottlenose dolphin was observed to support her newborn in a floating position on the surface during its first respiratory movements. It is interesting that other females who were there and then helped her in this.

21 slide ... There is a known case when a chimpanzee mother until then shook, tossed and shook her newborn, who did not show any signs of life, until he began to move and breathe. Monkeys use such "educational" techniques in relation to naughty cubs, such as slapping, biting, pushing, pulling on the hand, etc. Monkeys often support or plant cubs while climbing, form a "bridge" with their bodies over which cubs are transported from tree to tree etc.

22 slide Improving the nest, keeping it clean, and guarding the brood are also a vivid expression of parental instincts. So, for example, a female rabbit insulates the nest with down plucked from the belly, other animals arrange a bedding of soft plant materials. The mother's eating of dead fetuses, calves' feces, transferring them from a polluted shelter to another, changing the litter - all this is of great hygienic importance and, to some extent, helps to conceal the location of the brood from enemies, as they eliminate the smell of the den. The mother often licks the fur of the cubs, looks for fleas from them. Female raccoon dogs and badgers often carry small puppies out of their burrows "into the air" and, after a while, gently return them to the nest again. While temporarily moving away from the den or nest, the parents cover the cubs with bedding material or clog the entrance hole of the burrow. Returning to the brood, the parents usually linger for some time at a distance, go around the den, checking that there is no danger, such as a wolf or a fox. During the hatching period, hardened wolves, as a rule, do not attack livestock grazing near the den; if this "rule" is violated, it is usually not by adult animals, but by lingering near the lair. Parents "punish" disobedient babies by bringing them into submission. Observing, for example, a fox brood near a burrow, one can become a witness of how one of the parents, grabbing a cub that lingered on the surface after an alarm signal, strongly shakes it several times and drags it into the burrow.

7. Human. 23 slide. Caring for offspring reaches its highest development in a cultured person, doomed from the time of birth to prolonged helplessness and requiring prolonged preparation for social conditions of life. While mammals feed their children until they get the opportunity to feed themselves on their own, which usually happens after a few weeks and at most several months or two or three years after birth, in humans, caring for the offspring extends until the onset of the period. giving the opportunity to independently obtain food for themselves, and from the cultural classes - until the onset of full mental capacity for work, on which, in fact, the formation of a family is based, which has its main goal of raising children.

Many examples can be cited that people are wonderful parents and example for children. But nowadays, cases of abandonment of parental responsibilities, cruelty and violence towards children are often observed in human society, which is rarely seen in animals.

24 slide. It can be divided into three groups

Caring for offspring

Passive Active Proactive

Guys, give your examples of these groups:

IV Summing up the lesson.

Caring for offspring is …….

The evolutionary meaning of caring for offspring …….

Active care for offspring is …….

Passive offspring care is …… ..

Preventive offspring care is ……

V Lesson grades.

VI Messages D / Z. pp. 45-49 read and answer the question "Why have various forms of offspring been preserved, if not all of them are the most effective?"

Why have various forms of caring for offspring been preserved, if all of them are not as effective as possible?

Answers:

This is how nature works. These behaviors are mainly regulated by hormones secreted by the pituitary gland and ovary. In order for a species to continue to exist, each generation must leave behind offspring capable of reproduction. Most invertebrates and fish do not care for their offspring. They simply lay out thousands of eggs, only some of them produce juveniles, an even smaller number of them grow and multiply. A more reliable way to continue the race is after the birth of a limited number of cubs to provide them with food, protect them from predators, and even teach them some skills. Many animals take care of offspring in different forms. Most of them are endowed with special parental instincts, but in highly organized animals, individually acquired experience is also important.

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As you know, for the successful existence of a biological species, each generation of its representatives must leave behind offspring capable of reproduction. In the process of childbirth and the subsequent process of caring for the offspring, instinctive behavior is mainly realized. So, for example, immediately after the fetus leaves the birth canal, the female mammal frees it from the membranes, gnaws the umbilical cord, eats the membranes and the afterbirth, and actively licks the newborn. The cubs of the female, which does not provide primary care for them, are doomed to death in nature, and this trait itself, which is largely hereditary, is eliminated with them.

Successful survival of offspring depends to a large extent on the adequacy of parental behavior, which is an important factor in natural selection. Caring for offspring in many animals begins with preparation for their birth. Often seasonal migrations of animals are associated with moving to breeding sites, sometimes many thousands of kilometers from their habitat. Animals that do not make such long journeys also choose their nesting territory in advance, and many of them carefully guard it and prepare shelters - nests, holes, dens, adapted for future offspring.

Types of offspring care

In the animal kingdom, there are a variety of forms of caring for offspring: from complete absence to the most complex and long-term relationships between children and parents.

Complete lack of care for offspring

Note that in its simplest form, care for offspring is present in all organisms and is expressed in the fact that reproduction occurs only under conditions favorable for the offspring - in the presence of food, a suitable temperature, etc. In the future, most invertebrates and fish do not take care of the offspring. The success of the existence of such species ensures the massiveness of their reproduction. In the vastness of the ocean, many species of invertebrates and fish, gathering in giant flocks, lay millions of eggs, which are immediately eaten by a huge variety of carnivorous creatures. The only salvation for such species is colossal fertility, which nevertheless allows one to survive and survive to a sexually mature state for the minimum number of offspring necessary for the existence of a population. The number of eggs in many species of fish, laying eggs in the water column, is counted in hundreds and millions. For example, a female moth, a large sea pike living in the northern seas, spits up to 60 million eggs in one season, and a giant sea moonfish, weighing one and a half tons, throws up to 300 million eggs into the ocean waters. Left to chance, fertilized eggs, mixing with plankton or sinking to the bottom, die in myriad quantities. The same fate befell the larvae hatched from the eggs, however, there are still enough surviving ones to maintain the number of the species.

Carrying laid eggs on the body of one of the parents

The females of many marine animals attach the laid eggs directly to their bodies and carry them, as well as the hatched juveniles, until they become independent. Similar behavior is observed in many aquatic animals: starfish, shrimp and other crustaceans (Fig. 12.9). This behavior is the next step in the complexity of caring for offspring, but in general it is not particularly resourceful.

Rice. 12.9.

passive way of caring for offspring

The number of eggs laid is inversely proportional to the level of parental care. This pattern is well confirmed by starfish, among which there are both species that lay eggs directly into the water, where they are fertilized by the sperm of several males, and species that bear eggs on their bodies. In the species of the first group, the number of eggs maturing in the female's body reaches 200 million, while in sea stars that take care of the offspring, the number of eggs laid does not exceed several hundred.

Laying eggs in a medium previously selected or specially prepared by the female
Construction of nests and their protection until the birth of offspring

A more perfect type of care for the offspring can be considered the construction of a nest, the laying of eggs or eggs there and its protection until the moment when the growing juveniles leave it. This behavior is typical for a number of species of fish, spiders, octopuses, some centipedes, etc. Bearing eggs and fry in the mouth by males of some fish, as well as eggs and tadpoles on the hind legs of the midwife toad, can be attributed to a similar level of care. The described level is characterized by the absence of any interest on the part of the parents in the juveniles that are gaining independence.

Rice. 12.10.

Caring for offspring until they become independent

Long-term care for offspring is noted in some species of invertebrates and fish. The care of the offspring of social insects reaches great perfection.

Amphibians exhibit many examples of different types of parental behavior (Figure 12.10). In higher vertebrates, different ways of caring for offspring are observed, which depend primarily on the level of maturity of the newborn. In the most general terms, the following groups of parental behavior can be distinguished among them:

  • - rearing of offspring by one female or one male;
  • - raising offspring by both parents;
  • - raising pups in a complex family group.