Question: why have various forms of care for offspring been preserved, if all of them are not as effective as possible? The Importance of Parental Care Why Different Forms of Parental Care Have Survived
The success of the survival of the offspring to a large extent depends 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 animals are associated with movement 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 kingdom, there are the most different forms caring for offspring: from complete absence to the most complex and long-term relationships between children and parents. 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. 1. Complete lack of care for offspring. Most invertebrates and fish do not care for their offspring. The success of existence similar types ensures their mass 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 living in northern seas large sea pike - molva spawns up to 60 million in one season, and a 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 presented by chance, mixing with plankton or sinking to the bottom, die in myriad quantities. The same fate befell the larvae hatched from the eggs.
2. Bearing 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. This behavior represents the next step in the complexity of caring for offspring, but in general it is not very inventive.
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.
4. 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 a midwife toad or on the back of a male pippa of Suriname. In this case oral cavity or back act as a nest. This level is characterized by the absence of any interest on the part of parents to juveniles, which are slightly gaining independence.
5. 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.
Many examples different types parental behavior show amphibians. In higher vertebrates, there are different ways care for offspring, which depend primarily on the level of maturity of newborns.
In the most in general terms among them can be distinguished following groups parent behavior:
raising offspring by one female or one male;
raising offspring by both parents;
raising young in a complex family group.
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 them with food, protection from predators, and even teach 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 have special parental instincts However, in highly organized animals, individually acquired experience is also important.
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.
Caring for offspring in many animals begins with preparation for its birth. Often the seasonal migrations of animals are associated with moving to breeding areas, sometimes many thousands of kilometers away from their habitats. 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.
Many parental concerns are related to the rearing of offspring.
In most insects, care for offspring is simple. It is enough for the female to lay her eggs in a place where her larvae would find suitable food, for example, cabbage white butterfly larvae - cabbage. But some insects specially prepare shelter and food for their offspring, for example, honey-gatherers - wasps and bees. And the hunter wasps supply their larvae with crickets and grasshoppers. Before laying an egg, the Sphex wasp injects poison into the nerve ganglions of its prey, so that it remains motionless, but alive and serves as a fresh food supply for the larva for the entire period of its development. In dung beetles, not only females, but also males participate in the preparation of food for offspring - dung balls.
In many birds, the chicks hatch completely helpless and need frequent and regular feeding, some insectivorous birds feed their offspring up to 200 times a day! Sometimes parents (jays, nutcrackers, etc.) store food for future chicks from autumn. The offspring of brood birds - chickens, ducks, geese, etc. - are born independent, able to swim, walk, peck. Parents can only lead them to food, water, protect them from enemies, warm them (see Imprinting).
Mammal females feed their young with milk until they are able to eat other foods. In some animals, this period lasts several weeks, in others it is longer, and in great apes- some years. Gradually, parents begin to accustom children to adult food - show edible plants, learn to hunt.
Many animals protect offspring from enemies. In birds, colonial nesting serves this purpose, but solitary nesting birds can also unite to drive predators away from their nests. For example, if a cat or even a person tries to climb a tree where there is a crow's nest, 10-15 birds flock to it, screaming at the disturber of the peace.
Most mammals are more excitable than usual during the parenting period. Many large wild mammals attack people precisely when they threaten the cubs or are close to them. The moose does not allow anyone to the cub, including other moose.
In many mammals and birds, cubs stay with their parents for a long time, acquiring the skills necessary for life by imitation. This is the period of raising offspring. Parents teach cubs to choose and find food, water, and even medicinal plants, as well as shelters for sleeping or in case of bad weather. These forms of parental care are especially developed in mammals with a long lifespan. In elephants and some great apes, adolescence lasts up to 8-10 years. Not only parents, but also almost all adult members of the group take part in the upbringing of their offspring. Older brothers, and especially sisters or just females who do not have this moment their own offspring, they watch the cub, help feed it, care for it, play with it. In the event of the death of the mother, they, as a rule, adopt the orphaned cub. Such a collective form of care for offspring greatly increases the chances of its survival.
The highest development of care for offspring is received by a person. He not only takes care of the life support of children, but also educates them, transfers to them his life experience and knowledge accumulated in history.
We are all accustomed to seeing a mother with a stroller, or with a child in her arms. In each country, children are carried differently: in their hands, in a special backpack - “kangaroo”, in a cradle, just in fabric behind their shoulders, or on their chest - “sling”, on their shoulders (typical for their father). How do animals carry their babies? wild nature?
Animals after birth necessarily have a certain need to transfer their still completely helpless offspring somewhere. Monkeys, for example, have a sufficiently developed grasping reflex, so from birth they cling to their mother's hair with their hands, hanging down securely. At the same time, the mother can safely climb, and even jump on trees, without causing trouble to the baby. During this time, kids have time to learn all the intricacies of getting food, getting rid of enemies, assimilating the social laws of life. Opossums have surpassed the monkeys even more, they have not one, but several cubs that stick around the mother from all sides, holding on to the wool, and she does not lose anyone.
About Australian kangaroos everyone knows, they are nurtured in a special bag, where a miniature cub the size of a large bean grows to normal size. At first, the baby hangs on the nipple, sucking tightly, eventually begins to look out of the bag, and later jumps out. That is, kangaroos up to two years old can be in the mother's "pocket", and there are times when there can be 1-2 in the bag. summer child and on the nipple to hang a newly born baby.
Little hippos calmly "ride" in the water on the back of their mother. Elephants, although quite rare, raise their children on tusks and carry them to another place.
Mice, shrews save their numerous offspring by placing them in the form of a “train”: one baby grabs the mother’s hair above the tail with his teeth, the second takes the third one, the next one and so on until the last. So the whole family moves together. Rats are even better adapted to changes in their place of residence: if the rats are more or less adults, they follow each other, holding on to their tails, but if the children are very tiny, they transport them on their tail, stringing them like beads.
Crocodiles, having waited for the hatching of their offspring, which gives a voice from the sand, help them get out, tear the sand and carry it into the water in their terrible mouth, almost between the teeth. And not a single baby suffers from this. Some amphibians can also carry eggs, tadpoles, and small frogs on their backs.
Interesting stories naturalists report about turtles: the offspring of crocodiles and turtles are bred under the same conditions, their eggs are laid in the sand, and the babies hatch in the same way. Therefore, crocodiles can carry turtles with their babies, while suppressing their cruelty and aggression, that is, in this situation maternal instinct dominates.
Transportation in the teeth is the most common mode in many animals. Watching the animals, you can clearly see that they take the kids exactly by the withers, which is enough vulnerable spot. Parents can firmly clench the skin with their teeth, but they never cause harm, injury, or mutilation. Looking closely at pets - cats and dogs - this can often be seen. Cats are generally excellent mothers. They feed their kittens long enough breast milk until the baby grows up and can eat more adult food on its own. In order for the kitten to receive enough vitamin and energy, it is necessary to choose high-quality food. The best option royal canin cat food, and your kitten will always be energetic, cheerful and healthy.
The vedmediha mother does not indulge her baby with transfers, more often the bear cub runs after adults, turns over in a ball, overcoming obstacles, but when a real danger or obstacle threatens, the mother takes him in her teeth and transfers him to safe place. There are times when even a hedgehog in its teeth takes babies to a dry place if their hole is flooded with water.
Wolves, sensing danger, quickly, with feverish speed, carry their puppies in their teeth into a spare hole. But over the course of evolution, another thought has developed about wolves: hunters report that the she-wolf will not even give a voice, and not that she will rush at people who take her cubs into a bag. They are too afraid of humans.
Ungulates travel with children over long distances, holding them between their bodies, feeling their sides next to them. Moose become too aggressive when people approach them at a time when the baby is still on fairly thin, unstable legs, is nearby. In elephants, although the children look big, they are completely useless, even their personal trunk interferes with them, so it is safer to be on the side of the mother. Often the baby hides under the belly of adult elephants, and they support them with their strong trunks if necessary.
They write about the interesting relatives of our pigs - warthogs that they bring up in their babies the ability to twist from birth: having large fangs, in a tight hole, the mother never cares not to injure her children with them, they themselves must be able to dodge danger, therefore those who survived will be able to live on. According to statistics in the wild, the mortality of offspring is quite high. But, having learned the tricks of survival from childhood, the animal has a chance to live as long as it is given.
Some birds can carry not only chicks, but also eggs in their beaks. Some carry under the wings. Waterfowl “roll” babies on their backs, as they are ready for life immediately after hatching: they dried up and set off. A strange sight can be seen as ducklings run after a duck right across the water, although they have very little strength. But when fatigue sets in, they climb onto their backs and hide in their mother's feathers. The same can be observed in swans. On the mother's back, they not only rest and warm themselves, but also feel safe. Not every predator wants to get to the birds floating in the middle of the pond with chicks on their backs. On land, swans can also fight back, the wing beats are strong enough and can even kill a fox.
Incredibly, some birds carry their babies in their paws. For example, a forest sandpiper does it in this way. In case of danger, he grabs the chicks in his paws and flies away from her, even making zigzag movements in flight. And the black grouse, capercaillie, with the necessary signal, force the chicks to hide, or move imperceptibly towards the mother.
Scientists believe that a chick that has fallen out of the nest is of little concern to its parents. Seeing herons is proof. When a heron chick, staggering in a nest above the water, suddenly falls, the mother does not pick it up, although having a long beak it is quite easy to do this, apparently they think that "what has fallen is gone." But ornithologists think differently: this is natural selection, if there is no tenacity, then it is not entirely viable.
Unlike herons, almost all birds and other animals, risking their lives, try to save their offspring at any cost: they distract them from predators, make several nests, one of which is false, pretend to be sick and wounded, grab them in the teeth, make a terrible noise and din . After all, caring for offspring is one of the main concerns in life.
Of course, for some groups of organisms, care for offspring does not exist. Firstly, in fish, since the amount of reproductive material in them is quite large, and their genus has flourished for millions of years. Although some of them can be found guardianship:
- in salmon, which lays eggs in favorable conditions, migrating to spawning sites over considerable distances, after which it dies, fertilizing the environment for fry;
- stickleback fish spawns little, about 50-70 pieces, making a plant nest at the bottom of the reservoir, and after the appearance of babies, it protects it from enemies;
- the seahorse hides its fry in a bag on its stomach.
So, in the multifaceted animal world, a mother is ready to risk and sacrifice her life for the sake of her offspring. This is the most main law nature.
The value of caring for offspring
Of great importance, especially in immaturely born animals, is the parental care of offspring, that is, the actions of animals that ensure or improve the conditions for the survival and development of offspring. In the process of evolution, many groups of animals developed adaptations for the protection and nutrition of developing offspring from the parental individual. This includes passing embryonic stages development in the mother's body. However, the concept of "caring for offspring" applies only to the postembryonic period. In a number of cases, care for offspring is limited to creating a shelter and preparing food for future offspring, but the mother does not meet with him (preventive care for offspring). So, some wasps lay eggs on paralyzed insects, which are hidden in specially dug minks, but then they no longer care about the hatched larvae.
A higher form of care for offspring is care for offspring, which manifests itself in two main forms: passive and active. In the first case, adults carry eggs or young animals with them in special skin recesses, folds, bags. At the same time, young animals sometimes feed on the secretions of the mother. This form of care for offspring is found in certain types echinoderms, crustaceans, mollusks, spiders, fish (seahorse and needle, some tropical perciformes - cichlids), amphibians (midwife toad, American pipa, gastrotueca marsupiata frog), lower mammals (echidna, marsupials). With active care for offspring, adults perform specific actions aimed at providing for all or many areas of its life - insect larvae, juvenile fish, chicks, and young mammals. In addition to arranging shelters, feeding, heating, protecting, cleaning the surface of the body, etc., parents in many higher animals (birds and mammals) also teach their offspring (for example, to find food, recognize enemies, etc.).
It is the active care of the offspring, the highly developed care for it that makes immature birth possible, and thus all the features caused by it. mental development. At the same time, the evolution of care for the offspring was marked, on the one hand, by the intensification and differentiation of the actions of parents in relation to the offspring, on the other hand, by the strengthening of its dependence on adult animals. At the same time, fertility dropped sharply. However, the growing concern for offspring entails a growing contradiction between the needs of the parent and its offspring. This contradiction is regulated by natural selection in the direction of the greatest progress of the species. V. A. Wagner characterized this with the formula: the minimum of mother's sacrifices - the maximum demands of offspring.
Thus, progressive evolutionary acquisitions, which ensured a more flexible adaptation of a growing organism to the conditions of its life in postnatal ontogenesis, are of a very complex nature and include various forms of care for offspring, depending on the degree of maturity. The whole complex of these factors determines in each case the specific course of the postnatal development of behavior.
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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 hereditary, is eliminated with them.
The success of the survival of the offspring to a large extent depends 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.