Primitive care of offspring examples. Caring for offspring. Complete lack of care for offspring

Wedding dances and, alas, family worries This is a rare and unforgettable sight! Unfortunately, everyday worries do not allow many of the people to be present at the performances that wolf spiders ceremoniously play in the spring in front of their capricious spiders. Dr. W. Bristow

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Parental contribution (why in most animals females take care of offspring more often) R. Fisher's theory clarified one of the mysteries of Charles Darwin's theory of sexual selection. Namely: in what way preferences in the choice of a sexual partner could arise and form. However, in

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

Answers:

That's how nature works. These behaviors are mainly regulated by hormones secreted by the pituitary and ovaries. 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 thousands of eggs, only a part of them hatch into young, and an even smaller number grow and multiply. A more reliable way to continue the race is to provide food for them, protect them from predators, and even teach them some skills after the birth of a limited number of cubs. Caring for offspring is shown in various forms by many animals. 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 offspring, mainly instinctive behavior is realized. So, for example, immediately after the fetus leaves the birth canal, the female mammal releases it from the membranes, gnaws through the umbilical cord, eats the membranes and afterbirth, and actively licks the newborn. The cubs of a female who does not provide primary care for them are doomed to death in nature, and this trait itself, which is largely hereditarily conditioned, is eliminated with them.

The success of the survival of the offspring depends to a large extent on the adequacy of the behavior of the parents, which is an important factor in natural selection. Caring for offspring in many animals begins with preparation for its birth. Often, seasonal migrations of animals are associated with moving to breeding areas, 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, burrows, dens adapted for future offspring.

Types of care for offspring

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

Complete lack of care for offspring

Let us 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 offspring - in the presence of food, a suitable temperature, etc. In the future, most invertebrates and fish do not show concern for offspring. The success of the existence of such species ensures the mass character 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 the colossal fertility, which nevertheless allows the minimum number of descendants necessary for the existence of the population to survive and live to a sexually mature state. Hundreds and millions of eggs are calculated in many species of fish that lay their eggs in the water column. So, the female of the large sea pike living in the northern seas - molva spawns up to 60 million eggs in one season, and the giant sea fish-moon, reaching a weight of one and a half tons, throws up to 300 million eggs into the thickness of the ocean waters. Fertilized eggs left to chance, mixing with plankton or sinking to the bottom, die in myriad quantities. The same fate befell the larvae that hatched from the eggs, but the survivors are still enough to maintain the population of the species.

Carrying the laid eggs on the body of one of the parents

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

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 species of the first group, the number of eggs maturing in the body of a female reaches 200 million, while in starfish that take care of their offspring, the number of eggs laid does not exceed several hundred.

Oviposition in a previously selected or specially prepared environment by the female

Construction of nests and their protection until the birth of offspring

A more perfect type of care for offspring can be considered the construction of a nest, the laying of eggs or caviar there and its protection until the growing young leave it. This behavior is typical for a number of fish species, spiders, octopuses, some centipedes, etc. To a similar level of care can be attributed the bearing of 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. The described level is characterized by the absence of any interest on the part of parents to 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. Care for the offspring of social insects reaches great perfection.

Amphibians demonstrate many examples of different types of parental behavior (Fig. 12.10). In higher vertebrates, different ways of caring for offspring are observed, which depend primarily on the level of maturity of newborns. 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 cubs in a complex family group.

Theme of the lesson "Care 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 adaptation do you know? Name them and give examples

How to understand what fitness is wearing relative nature?

2. Biological dictation.

Insert the term that this definition means.

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

2. Coloration to help hide in environment, is called ...

2. The acquisition of similarity with some object is called ...

3. The similarity between unprotected and protected species is called ...

4. Any ... is relative.

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

III . Formation of new knowledge:

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

How is care for offspring manifested in different animals?

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

4 slide. Class Arachnids. A female karakurt, a deadly poisonous spider that lives in Central Asia turns out to be quite a caring mother. 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 of the mother's poison, and then, when she dies, they hibernate under a dense shell.

5 slide. Crustacean class. Crayfish do not abandon their offspring either. They carry eggs with them. When rachata hatch from eggs, they attach to the mother's abdominal legs. And there they remain until they become independent.

2. Class Fish.

6 slide. For many millions of years, fish have developed amazing ways of caring for their offspring. Rybka tilapia carries eggs 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. On a freshwater fishbitterness during reproduction, the ovipositor grows. The female lays eggs in the mantle cavity of bivalves. This is where the fry of the mustard develop. Some fish build nests for fry. Nests are built from foam by macropods, gourami, labyrinth fish.

8 slide . The male three-spined stickleback also builds a nest for the female. When the nest is ready, the male drives the females there one by one, who lay several eggs there. 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 lumpfish found in the Barents and White Seas. At low tide, when the eggs are aground, the lumpfish draws water into the stomach, splashes the eggs from the mouth.

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

3.Class amphibians .

11 slide. Most egg-laying amphibians do not exhibit any parenting behavior, and after spawning leaves water bodies, leaving their offspring to fend for themselves. However, for example, the bullfrog inhabiting the islands of the Caribbean has been guarding the eggs and the larvae that have hatched from them for a long time. 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 neighboring puddle, along which he then drives the tadpoles into it. Tree frogs. Dwelling in crowns rainforest, many tree frogs face 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 their offspring. In some species, parents build special nests on plants that replace reservoirs for larvae, in others they build artificial reservoirs, in others they hatch eggs and larvae on themselves.

12 slide. Thus, tropical leaf frogs lay their eggs on the leaves of trees and guard the masonry until the larvae hatch. The tadpoles hatched from the eggs crawl onto the wet back of the male, and he transfers them one by one to micro-reservoirs located right there on the trees, in the axils of the leaves. In the absence of suitable 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 pond, do not starve. In one species of leaf climbers, the female carries the tadpoles into the reservoirs 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 . Very caring fathers are the males of the land European midwife toad. Females lay their eggs on land in the form of two cords containing 20-50 eggs each. The male helps the female to get rid of them. Grasping the cords with the toes of his hind legs, he pulls them out and wraps them around himself. An active male can get eggs from two or three females in this way. During the entire period of caviar development, the male wears cords on himself. At the end of this period, the male goes in search of a reservoir, where the larvae hatch. After that, he is freed from the empty cords. Some species of frogs hatch eggs and larvae in special brood bags. During the breeding season, the skin that forms the bag 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, similar to honeycombs. Such a living baby stroller with 200 seats! He carries tadpoles on himself until they stand on their feet.

14 slide. Australian marsupial tree frogs pouches-pockets are located in the cloacal region of males. The development of eggs takes place on the ground, and the larvae that emerge from it themselves crawl into the bags of their parent. A large yolk sac provides them with sufficient nutrition and allows them to stay in brood sacs 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 care about the fate of the cubs that are 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 made 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 breed on certain parts of the sea coasts. They gather in 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 Atlantic Ocean, overcomes a distance of 2600 km, fighting currents and maintaining an accurate course. On land, the female moves with great difficulty, clumsily pushing her body forward and leaving behind a wide track, similar to the track of a caterpillar tractor. She moves slowly and strives for one single goal - to find a suitable place for masonry. Having got out of the surf line, the female carefully sniffs the sand, then rakes it and makes a shallow hole, in which she then digs a jug-shaped nest with the help of only her hind limbs. The shape of the nest is the same in all species of turtles. During the breeding season, females lay eggs two to five times; in laying from 30 to 200 eggs. There is no parental behavior in turtles; 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. Bird class.

It rarely happens that an incubating bird, or especially a bird at the 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 arm with a blow of a wing. More often, however, the birds "take 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 run and the desire to pounce on the enemy. The combination of these aspirations creates a complex behavior of the bird, which seems conscious to the observer. When the chicks have hatched from the eggs, the parents begin to feed them. During this period, there is a strict division of labor.

17 slide. In black grouse, capercaillie and ducks, only one female leads the brood. The male does not care about the offspring. Only the female incubates at the white partridge, 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 chicks. As a rule, both parents feed them, but often one feeds vigorously, while the other is lazier. 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, who is inseparably at the nest. The female tears the prey into pieces and gives them to the chicks. If the female died for some reason, the male will put the brought prey on the edge of the nest, and in the meantime the chicks will die of starvation. Small birds feed chicks very often. The great tit brings food to the chicks 350-390 times a day, the nuthatch - 380 times, the demoiselle swallow - up to 500 times, and the American wren - even 600 times. The swift sometimes flies as far as 40 km from the nest in search of food. He brings to the nest; not every midge caught, but a mouthful of food. He glues the prey with saliva into a ball, and having flown to the nest, he deeply sticks balls of insects into the throats of the chicks. In the first days, the swifts feed the chicks in such enhanced 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 still need parental care for a long time. Only gradually do they learn to find and peck prey themselves.

6. Mammals.

19 slide. Mammalian care for offspring can take many forms. The female echidna bears the laid egg in the bag formed on the belly. The platypus incubates 1-2 eggs in a hole where it arranges a nest for this.

20 slide. The female kangaroo carries her cub for 8 months in a bag on her stomach. The young kangaroo, who has grown up and has already begun to feed on his own, uses it as a temporary shelter for a long time. At the Florida Aquarium, a female bottlenose dolphin was observed supporting her newborn in a floating position on the surface during his first breaths. It is interesting that other females who were right there also helped her in this.

21 slide . A case is known 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 as spanking, biting, pushing, pulling the arm, etc. Monkeys often support or help cubs when climbing, form with their bodies a "bridge" along which the cubs are transported from tree to tree etc.

22 slide Improvement of the nest, keeping it clean, guarding the brood are also a vivid expression of parental instincts. So, for example, a female rabbit insulates the nest with fluff plucked from her belly, other animals arrange a litter of soft plant materials. Mother eating dead fetuses, feces of cubs, transferring them from a contaminated shelter to another, changing bedding - all this is of great hygienic importance and to some extent helps to hide the location of the brood from enemies, as they eliminate the smell of the lair. The mother often licks the fur of the cubs, looking for fleas from them. Female raccoon dogs and badgers often take small puppies out of their burrows "into the air" and after a while carefully return them to the nest again. Temporarily moving away from the den or nest, the parents cover the cubs with bedding material or clog the burrow inlet. Returning to the brood, the parents usually linger for some time at a distance, go around the den, checking the absence of danger, such as a wolf or a fox. During the breeding season, mature wolves, as a rule, do not attack livestock grazing near the den; if this "rule" is violated, then usually not by adult animals, but by over-flyers that lingered not far from the lair. Parents "punish" disobedient cubs, bringing them into obedience. Observing, for example, a fox brood at a hole, one can become a witness of how one of the parents, grabbing a cub that lingered on the surface after an alarm signal, shakes it vigorously several times and drags it into the hole.

7.Man. 23 slide. Care for offspring reaches its highest development in a cultured person, doomed from the time of birth to prolonged helplessness and requiring lengthy preparation for social conditions life. While mammals feed their children until they are able to feed themselves, which usually happens after a few weeks and at most a few months or two or three years after birth, in man the concern for offspring extends to the onset of a period which makes it possible for the cultural classes to independently earn their living, and for 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 as its main goal the upbringing of children.

Many examples can be given that people are excellent parents and an example for children. But at the present time, often in human society, there are cases of abandonment of their parental responsibilities, cruelty and violence against children, which is rarely seen in animals.

24 slide. It can be divided into three groups

Caring for offspring

Passive Active Preventive

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 of offspring is …….

Passive care of offspring is ……..

Preventive care for offspring is ......

V Lesson grades.

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